socioeconomic and sex differences in adolescents’ dietary ...286755/fulltext02.pdfdapi nl, janlert...

Socioeconomic and sex differences in adolescents’ dietary intake, anthropometry and physical activity in Cameroon, AfricaLéonie Nzefa Dapi

Department of Public Health and Clinical Medicine Epidemiology and Global HealthUmeå University 2010

Department of Public Health and Clinical Medicine, Epidemiology and Global HealthUmeå University, SE- 901 87 Umeå, Swedenwww.umu.se

Léonie N

zefa Dap

i Socioeconomic and

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Umeå University Medical DissertationNew series No. 1327ISSN 0346-6612 ISBN 978-91-7264-942-2Edited by the dean of the Faculty of Medicine

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Umeå University Medical DissertationNew Series No. 1327 ISSN: 0346-6612 ISBN: 978-91-7264-942-2

Epidemiology and Global HealthDepartment of Public Health and Clinical Medicine

Umeå University, SE-901 87 Umeå, Sweden

Socioeconomic and sex differences in adolescents’ dietary intake, anthropometry and physical activity in Cameroon, Africa

Léonie Nzefa Dapi2010

Epidemiology & Global Health Department of Public Health and Clinical Medicine

Umeå University, Sweden

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ISSN: 0346-6612-1327 ISBN: 978-91-7264-942-2Epidemiology and Global HealthDepartment of Public Health and Clinical MedicineUmeå UniversitySE-901 87 Umeå, Sweden

©Léonie Nzefa DapiPrinted by Print & Media, Umeå University, Umeå 2010

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AbstrAct Background: People in Cameroon are experiencing a dietary transition character-ized by changing from traditional food habits to increased intake of highly processed sweet and fatty food. The rapid change in food pattern combined with an increased sedentary lifestyle has resulted in a rather high prevalence of obesity, hypertension, cardiovascular diseases and type 2 diabetes. Nutritional intake is important during adolescence for growth spurt, health, cognitive development and performance in school.

Objective: The aim of this thesis was to assess dietary intake, anthropometry and physical activity of adolescents according to sex and socioeconomic status (SES) and to investigate food perceptions of adolescents living in urban and rural areas of Cameroon.

Methods: Girls and boys, 12-16 years of age, were randomly selected from schools in urban and rural areas. Food frequency questionnaire, 24-hour dietary and physical activity recalls, anthropometric measurements, qualitative interviews and a back-ground questionnaire were used for data collection.

Results: The proportion of overweight was three times higher in girls (14%) com-pared to boys (4%). Stunting and underweight were more common among boys (15% and 6 %) than girls (5% and 1%). The prevalence of stunting was two times higher among the urban adolescents with low SES (12%) compared to those with high SES (5%). The rural adolescents had more muscle that the urban adolescents. The rural adolescents ate in order to live and to maintain health. Urban adolescents with low SES ate in order to maintain health, while those with high SES ate for pleasure. More than 30% of the adolescents skipped breakfast in the urban area. Urban adolescents with high SES and girls reported a more frequent consumption of in-between meals and most food groups compared to the rural adolescents, boys and those with low SES. Over 55% of the adolescents had a protein intake below 10% of the energy (E%). Twenty-six percent of the adolescents had fat intake below 25 E%, and 25% had fat intake above 35 E%. A large proportion of the adolescents had an intake of micronu-trients below the estimated average recommendation. Boys and the adolescents with low SES reported a higher energy expenditure and physical activity level than girls and the adolescents with high SES, respectively. Both under- and over-reporting of energy intake were common among the adolescents.

Conclusions: The present study showed that nutrient inadequacy, stunting, un-derweight, as well as overweight and obesity were common among the adolescents in Cameroon. Therefore an intervention program targeting both under- and over-nutrition among school adolescents is needed. Sex and socioeconomic differences also need to be considered.

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summAry in FrenchL´état nutritionnel des adolescents en fonction du sexe et du statut socioécono-mique au Cameroun.

Contexte: La population camerounaise connait une transition alimentaire caractérisée par une évo-lution des habitudes alimentaires traditionnelles vers une alimentation riche en sucre et en graisse. L’évolution rapide du schéma d’alimentation, combinée à une sédentarité croissante a entraîné une plus forte prévalence de surpoids et d’obésité, de maladies cardiovasculaires et du diabète de type 2. Outre les maladies cardiovasculaires, les maladies infectieuses et les carences alimentaires sont encore répandues dans le pays. L’apport nutritionnel est important pendant l’adolescence pour la poussée de croissance, la santé, le développement cognitif et le rendement à l’école.

Objectif: L’objectif de cette thèse était d’évaluer l’apport alimentaire, l’anthropométrie et l’activité physique des adolescents selon le sexe et le statut socioéconomique (SSE) et d’en-quêter sur les perceptions alimentaires des adolescents vivant en zones urbaine et rurale au Cameroun.

Méthodes: Les filles et les garçons, 12-16 ans ont été choisis au hasard dans les écoles en zones urbaine et rurale. Un questionnaire sur la fréquence alimentaire, le type d’aliments sur 24 heures, l’activité physique sur 24 heures, les mesures anthropométriques, des entrevues qualitatives et le questionnaire de base ont été utilisés pour la collecte de données.

Résultats: Les filles étaient plus en surpoids et obèses (14%) que les garçons (4%). D’autre part le retard de croissance et d’insuffisance pondérale ont été plus fréquent chez les garçons que les filles. La prévalence du retard de croissance a été deux fois plus élevée parmi les adoles-cents en milieu urbain de faible SSE (12%) comparativement à ceux dont le SSE est élevé (5%). Les adolescents en zone rurale ont plus de muscles que les adolescents en milieu urbain. Les adolescents en zone rurale mangent pour vivre et pour être en bonne santé. Les adolescents en milieu urbain de faible SSE mangent afin d’être en bonne santé, tandis que ceux dont le SSE est élevé mangent pour le plaisir. Plus de 30% des adolescents sautent le petit déjeuner dans la zone urbaine. Les adolescents en milieu urbain, surtout ceux avec un SSE élevé et les filles font état d’une consommation d’aliments plus fréquente entre les repas et la plupart des groupes alimentaires, par rapport aux adolescents de la zone rurale, les garçons et ceux de faible SSE. Plus de 55% des adolescents avaient un faible apport de protéines en comparaison avec les recommandations. Vingt-cinq pour cent des adolescents ont une consommation insuffisante de matières grasses et 26% avaient un apport élevé de matières grasses en comparaison avec les recommandations. La dose médiane de la plupart des micronutriments a été inférieure à la dose journalière recommandée et une grande proportion des adolescents avait un apport de micronutriments en dessous de la recommandation moyenne estimée. Les garçons et les adolescents de faible SSE avaient une dépense élevée d’énergie et du niveau d’activité physique par rapport aux filles et aux adolescents ayant un SSE élevé. La sous-estimation ainsi que la surestimation de l’apport énergétique était courante chez les adolescents.

Conclusions: La présente étude montre que l’insuffisance en nutriments, le retard de croissance, l’insuffisance pondérale, ainsi que le surpoids et l’obésité étaient fréquents chez les adolescents au Cameroun. C’est pourquoi un programme d’intervention de santé visant à la fois la sous-et surnutrition chez les adolescents est nécessaire. Le sexe et les différences socio-économiques doivent également être pris en considération.

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summAry in swedishKostintag, antropometri och fysisk aktivitet i relation till socioekonomi och kön hos ungdomar i Kamerun, Afrika.

Bakgrund: Befolkningen i Kamerun genomgår för närvarande en förändring i kosthållnin-gen. Istället för traditionella kost äter man en allt mer bearbetad, söt och fet mat. Den snabba förändringen av kostvanorna sker samtidigt som människor rör sig allt mindre. Detta har resulterat i en tämligen hög förekomst av fetma, högt blodtryck, hjärt-kärlsjukdomar och typ 2-diabetes. Näringsintaget är viktigt under tonårstiden på grund av tillväxtspurten, hälsan, den kognitiva utvecklingen och prestationerna i skolan.

Syfte: Syftet med denna avhandling var att skatta unga män och kvinnors kostintag, antro-pometri och fysiska aktivitet olika sociala grupper och att studera hur tonåringar, i staden och på landet, uppfattar mat.

Metod: Flickor och pojkar i åldern 12-16 år valdes slumpmässigt från skolor på landet och i staden. Frekvensformulär, 24-timmars kostanamnes och anamnes på den fysiska aktiviteten, antropometriska mått, kvalitativa intervjuer liksom bakgrundsfrågor användes för att samla in data.

Resultat: Andelen överviktiga var tre gånger högre bland flickor (14 procent) jämfört med pojkar (4 procent). Tillväxthämning och undervikt var vanligare bland pojkar än flickor (15 respektive 6 procent). Förekomsten av tillväxthämning var två gånger vanligare bland tonåringarna i staden med låg socioekonomisk status (12 procent) jämfört med dem med hög (5 procent). Ungdomarna på landet hade mer muskelmassa än ungdomarna i staden. På landsbygden åt man för att leva och bibehålla hälsan. Ungdomarna i staden med låg so-cioekonomisk status åt också för att bibehålla hälsan, medan de som hade högre status åt för nöjets skull. Över 30 procent av ungdomarna i staden hoppade över frukosten. Ungdomar i staden med hög socioekonomisk status, liksom flickor, rapporterade oftare mellanmål och konsumtion av de flesta födeämnesgrupper. Över hälften av ungdomarna hade ett proteinintag som låg under 10 energiprocent. Tjugosex procent av ungdomarna hade ett fettintag under 25 energiprocent och en fjärdedel hade ett fettintag som låg över 35 energiprocent. En stor andel av tonåringarna hade ett intag av mikronäringsämnen som låg under det rekommenderade. Pojkar och flickor med låg socioekonomisk status rapporterade högre energiförbrukning och fysisk aktivitet än flickor med hög status. Såväl under- som överrapportering av energiintaget var vanligt bland tonåringarna.

Slutsats: Den här studien visade att bristande näringsintag, tillväxthämning liksom övervikt och fetma var vanligt bland tonåringar i Kamerun. Därför behövs ett förebyggande program som riktar sig till både över- och undernärda skolungdomar. Kön och socioekonomiska skill-nader måste beaktas i ett sådant program.

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List oF pApersThe thesis is based on the following papers:

Dapi NL, Janlert U, Nouedoui C, Håglin L. Adolescents Food Habits and Nutritional Status in Urban and Rural Areas in Cameroon, Africa. Scand J Nutr 2005; 49: 151-158.

Dapi NL, Janlert U, Omoloko C, L Dahlgren, Håglin L. “I eat to be happy, to be strong and to live”. Food perceptions of rural and urban adolescents in Cameroon, Africa. J Nutr Educ Behav 2007; 39:320-326.

Dapi NL, Janlert U, Nouedoui C, Håglin L. Socioeconomic and gender differences in adolescents nutritional status in urban Cameroon, Africa. Nutr Res 2009;9 (5):313-319.

Dapi NL, Hörnell A, Janlert U, Stenlund H, Larsson C. Energy and nutrient intake in relation to sex and socioeconomic status among school adolescents in urban Cam-eroon, Africa (Submitted).

The articles have been reprinted with permission from the publisher.

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AbbreviAtionsAFA Arm Fat AreaAMA Arm Muscle AreaAMDR Acceptable Macronutrient Distribution RangesANOVA Analysis of VarianceBINS Becel Institution Nutrition SoftwareBMI Body Mass IndexBMR Basal Metabolic Rate CDC Centers for Diseases Control and PreventionEAR Estimated Average RequirementEE Energy ExpenditureEI Energy IntakeE% Energy percentage (proportion of energy from a specific source, e. g fat E%)FAO Food and Agriculture OrganizationFcfa Francs of Financial Cooperation in Central AfricaFFQ Food Frequency QuestionnaireHBSC Health Behavior in School-aged ChildrenMET Metabolic Energy TurnoverMUAC Mid Upper Arm CircumferencePAL Physical Activity LevelRDA Recommended Dietary AllowanceSES Socioeconomic StatusSPSS Statistical Package for the Social Sciences TSF Triceps SkinfoldWHO World Health Organization WHR Waist Hip Ratio24-HDR 24 -Hours Dietary Recalls

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GLossAryAnthropometry The study of human body measurement for use in anthropological classification and comparison.

Adolescence The period of life beginning with the appearance of secondary sex characteristics and ending with the cessation of somatic growth.

PubertyThe process of physically developing from a child to adult.

Nutritional status A measurement of the extent to which the individual’s physiologic need for nutrients is being met. It can be assessed by using dietary history and dietary intake, biochemi-cal data, clinical examination, health history, anthropometric data and psychological data.

Food frequency questionnaireA method of dietary assessment in which the questions relate to how often foods are consumed.

24-hour dietary recallA method of dietary assessment in which the individual is asked to remember eve-rything eaten during the past 24 hours.

24-hour physical activity recallA method of physical activity assessment in which the individual is asked to remember all physical activities during the past 24 hours.

Underweight Defined as the body mass index less than the fifth percentile.

Overweight Defined as the body mass index more than 25 kg/m2.

StuntingDefined as low height for age. Children who fall below the fifth percentile of the refer-ence population in height for age are defined as stunted.

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To my father

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tAbLe oF contentspreFAce ............................................................................................................................................................................................................................ 3

introduction ................................................................................................................................................................................................... 5

General information and health situation ................................................................................................................... 5 Food and nutrition ........................................................................................................................................................................................ 5 Nutrient deficiencies and malnutrition ........................................................................................................................... 6

Economic crisis influencing nutrition ................................................................................................................................ 6

Adolescents’ nutrition .............................................................................................................................................................................. 6

School system ...................................................................................................................................................................................................... 7

Ethical consideration ................................................................................................................................................................................. 8

objectives ............................................................................................................................................................................................................... 9

General objective ............................................................................................................................................................................................ 9

Specific objectives ........................................................................................................................................................................................ 9

methods ......................................................................................................................................................................................................................... 11

Study areas and population ............................................................................................................................................................ 11

Yaoundé ........................................................................................................................................................................................................................ 12

Bandja .............................................................................................................................................................................................................................. 12

Sampling ...................................................................................................................................................................................................................... 13

Sampling for paper I ............................................................................................................................................................................... 13

Sampling for paper II .............................................................................................................................................................................. 13

Sampling for paper III ............................................................................................................................................................................ 13

Sampling for paper IV ........................................................................................................................................................................... 14

Study personnel ................................................................................................................................................................................................ 14

Data collection .................................................................................................................................................................................................... 14

Background questionnaire (papers I–IV) ..................................................................................................................... 14

Qualitative method (paper II) ....................................................................................................................................................... 14

Anthropometry and puberty assessments (papers I, III and IV) .............................................. 15

Dietary intake assessment ................................................................................................................................................................. 15

Food frequency questionnaire (papers I and III) .................................................................................................... 15

24-hour dietary recall (paper IV) .............................................................................................................................................. 16

Physical activity assessment (paper IV) ....................................................................................................................... 17

Identifying mis-reporters of energy intake (paper IV) ............................................................................ 18

Data analysis .......................................................................................................................................................................................................... 18

Statistical analysis .......................................................................................................................................................................................... 18

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resuLts ............................................................................................................................................................................................................................. 21

Characteristics and physical activity of adolescents ................................................................................. 21

Anthropometry and puberty of adolescents ........................................................................................................ 22

Stunting, underweight and overweight ......................................................................................................................... 24

Adolescents’ food perception ...................................................................................................................................................... 24

Food intake and meals pattern .................................................................................................................................................. 25

Energy and nutrient intake of adolescents .............................................................................................................. 29

Validity of reported energy intake ........................................................................................................................................ 34

discussion ................................................................................................................................................................................................................ 35

Adolescents’ food perceptions and habits ............................................................................................................... 35

Food groups consumption and meals pattern ................................................................................................... 36

Physical activity ................................................................................................................................................................................................. 36

Anthropometry .................................................................................................................................................................................................. 36

Nutrient and energy intake .............................................................................................................................................................. 37

Validity of reported energy intake ........................................................................................................................................ 39

Health consequences ................................................................................................................................................................................ 40

Limitations and strengths ................................................................................................................................................................... 40

concLusions And recommendAtions ................................................................................................... 43

Nutritional education at school ................................................................................................................................................. 43

AcknowLedGements ....................................................................................................................................................................... 45

reFerences ............................................................................................................................................................................................................ 47

Appendix ....................................................................................................................................................................................................................... 51

Food pictures booklet ............................................................................................................................................................................. 51

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preFAceWhen I was a pupil in Cameroon, we use to walk home during lunch time and eat home made food, sleep (siesta) and walk back to school in the afternoon. Since 1995, schools in Cameroon have changed their schedule with a shorter lunch break period, so pupils have to stay in school during lunch break, despite the fact that there are no school restaurants. Besides this, with modernization, life has become more sedentary with increased car transportation and television viewing, and fewer domestic du-ties. My interest about adolescence came from the fact that it is a period in life when teenagers begin to develop real independence from their parents, including making decisions about the food they eat. Furthermore, in 2002 I was invited to present in-formation about food and nutrition in the most affluent private secondary school in Douala Cameroon. So, intrigued by the rapid change in dietary habits and physical activity, especially among adolescents’ students, I decided to undertake a study about food and nutrition among adolescents in order to provide my country with informa-tion about their nutrition to prevent nutrition related ill-health among youths and adults. My questions were: what do they eat? why do they eat the way they do? what was their nutritional status? Looking at attendance as well as performance in school in relation to nutritional status was also a part of my concern.

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introduction

General information and health situation Cameroon is located in central Africa with a land area of 475 442 km2 and 18 millions inhabitants (1, 2). The gross national income per capita is 2060 US dollar and gross primary school enrolment is about 90% with a resulting fairly high literacy rate of around 79% (1-3). The country has an economy more promising than other countries in the region, because of natural resources mainly oil, bauxite, gas, wood, gold, and favorable agricultural conditions with coffee, cocoa, cotton, banana, plantain, maize, cassava, millet, sorghum, cocoyam, pineapple, groundnuts, cereals and roots (1). The proportion of urbanization in 2004 was 49%, poverty prevalence was 32% in 2001, and 51% of the population has water supply at home (3, 4).

The official languages are French and English and there are over 230 ethnic groups in the country speaking dozens of languages. The climate is tropical with four sea-sons- two rainy seasons and two dry seasons.

There is no public health insurance in Cameroon; people have to pay for any medi-cal consultation or buy medication. There is one physician per 5673 inhabitants and the main prevalent diseases are malaria (11%), diarrhea diseases, tuberculosis and respiratory diseases (5). The prevalence of HIV-AIDS is 5.5%. Besides infectious diseases, non-communicable diseases including hypertension (24%), cardiovascu-lar diseases, type 2 Diabetes mellitus (6%), obesity/overweight (21 vs. 15%, women vs. men, respectively) and some cancers are prevalent in the country (6-10). Infant mortality rate among under five years of age is 74/1000 and life expectancy is 59 years of age (3).

Food and nutrition Agriculture remains a key sector of the economy, making Cameroon almost self-sufficient in food (11). Food consumption in Cameroon is traditionally distributed into three main meals daily (breakfast, lunch and dinner) but people in the rural area and those with low socioeconomic status (SES) eat the same type of food for lunch and dinner (6). Cereals (maize, millet, sorghum), starch/tubers (cassava, potatoes, yam, cocoyam) and plantain are the main components of the diet (5). Meals are usually composed of one of the basic foods (plantain, cassava, maize or sorghum) with a sauce composed of green leafy vegetables or legumes and oil (6). Green leafy vegetables are consumed as sauce mixed with tomatoes or groundnuts. Palm oil is commonly consumed. Meat and fish are consumed depending on the economic status of the family. Alcohol is consumed mainly by male adults (6). A study on habitual diet in Cameroon shows that the rural diet is more or less based on the traditional staple foods, while the urban dwellers incorporate more modern foods into their diet (6). There is inequality of access to food in the country with the urban area having more access to food but with great difference in energy intake among people (5). The percentage of food insecurity (no access to enough food) in Cameroon was 26% in

INTRODUCTION

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2000 and the rural population was more vulnerable to underfeeding than the urban population (5). Food insecurity mostly affects people with low economy (11, 12).

Nutrient deficiencies and malnutritionNutrient deficiencies and malnutrition are common in Cameroon. Iron deficiency is the major cause of anemia with a prevalence of 57% among children under five years of age and 27% among 15-45 years of age women (5). It affects people with low SES more than those with high SES. Iodine deficiency is endemic with a prevalence of 22% (13). Vitamin A deficiency prevalence is 39% in the country (5) while the prevalence of vitamin E deficiency was found to be 45% in the North of Cameroon in 2005 (14). The prevalence of underweight was 15%, stunting was 35%, and overweight was 9% among children under five years of age in 2004 (2). Chronic malnutrition among children under five years of age was 30% in 2006 (21% in the urban and 38% in the rural area) (15). A 2004 demographic health surveys showed that 7% of women 15-49 years of age were underweight (10).

Economic crisis influencing nutrition Cameroon has had several important changes in the past, such as an economic crisis from 1986 to 1995 (11), resulting in a reduction of government workers salaries in 1993 (30% in January, and an additional 50% in November) and currency depreciation in January 1994 (15). The consequences of these events were poverty and an increase of local food prices such as cassava, plantain, maize, cocoyam, potatoes, nuts, beans, palm oil, meat and fish. In addition, cassava and plantains were not always available because of the low production compared to the high demand and seasonal variation (16). So, some of these local food items were almost unaffordable to the population (16). Furthermore, imported rice and chicken became cheaper and more available than local foods (16). Thus, some people switched from local food to pasta, imported chicken and rice.

With the economic crisis, women became more involved in the work force and consequently spent less time for food preparation; therefore, easily cooked food and bread became popular at home especially in the urban area (16).

There were also a change of school and government schedules in 1993 (previously 7 am-12 noon and 2-5 pm) (12, 16). Furthermore, with the new school schedule and since there were no school restaurants pupils were forced to consume sandwiches and fast food such as doughnuts, pastry, chips, candies, chocolate, and sweet beverages that were sold by vendors within and outside the school yard.

Adolescents’ nutritionAdolescents (10-19 years, WHO) represent 24% of the population in Cameroon and have been neglected especially when it comes to studies regarding their nutritional intake, although there are several studies about their sexual habits. Adolescence is a period of intense physical and cognitive development with increased nutritional needs due to growth spurt and sexual maturity (17). A good nutrition in adolescence

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INTRODUCTION

is important not only for good health but also for attendance and performance at school as well as learning process. During the adolescence, the dramatic increase in energy and nutrient requirements coincides with changes in other factors that may affect adolescents’ food choices, nutrient intake, and hence nutritional status. These factors include the quest for independence and acceptance by peers, parents, teachers, fashion, media, knowledge, preoccupation with self-image, increased mo-bility, food availability and the economical situation, sanitation, cultural beliefs and school (17-21). During this period adolescents gain up to 50% of their adult weight, 50% of their adult skeleton mass and 20% of their height (22). Soft tissues, organs, and even red blood cell mass increase in size. As a result, nutritional requirements peak during adolescence. Eating practices affect young people’s risk for a number of health problems such as nutritional deficiencies, obesity, cardiovascular diseases and some cancers (18, 23). Deficits in macro and micronutrients can impair growth, delay sexual maturation and later affect adult health (24).

The adolescent daily recommendation of calcium exceeds that for every other stage of life except pregnancy (17). Calcium is important throughout the teenage years as it is necessary for building strong bones and ensuring good health and wellbeing later in life (25, 26). The need for iron is important because iron is used to increase muscle mass and circulating red blood cell mass (17, 26). Girls are more at risk of iron deficiency because of monthly loss through menstruation. Iron deficiency can impair cognitive function and physical performance. Folate is particularly important because many adolescents’ girls become pregnant and folate deficiency has been cor-related with neural tube defect in the fetus (17, 24, 25). The B vitamins enhance the immune system and nervous system, keep the skin and muscles healthy, encourage cell growth and participate in the metabolism of carbohydrates, proteins, fats, min-erals and other vitamins (25, 26). Vitamin A is important for vision, epithelial tissue and it increases capacity to resist malaria (25, 26).

School systemSchools are socializing environments were children are exposed to many hours dur-ing their adolescence (27). In the past decade, an increasing number of children in developing countries have been enrolled in schools. However, their performance levels have often been disappointing (28). It was suggested that poor health and nutritional status may hinder these children’s ability to learn, and hunger in school is one of the conditions that has been implicated (16, 28). Under-nutrition leads to impaired intellectual capacity and malnourished children are more often sick and more often have physical as well as mental disabilities (5, 16).

In Cameroon, kindergarten is two years starting from four years of age, primary school is six years and attendance is compulsory, and secondary and high school are seven years. There are both public and private schools. Public schools are almost free of charge and children have to buy books and uniforms. Weekly school days are from Monday to Friday and Wednesday afternoon is free. School attendance rate in Cameroon is 79% for boys and 76% for girls; education represents 5% of the

INTRODUCTION

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national budget of the country and the mean expenses for schooling is 707 Euro per child per year (3). The net schooling rate is 94% in Yaoundé and 91% in the rural western province (4, 29). The mean distance to the nearest school is 1.7 km. Most of the schools in the urban areas have nurses but not in the rural areas. The main courses at secondary school are mathematics, English, computer sciences, French (essay, grammar and dictation), history, geography, biology, civic instruction, sport and home sciences. The duration for a lesson is one hour and there are about 80 pu-pils per classroom. The school grade system is from 0 to 20, and 10 is the minimum grade needed to pass the academic year. The prevalence of repetition of a school year due to low results is 23 % (3).

Figure 1. Picture of classroom in Yaoundé.

Ethical consideration Permission to carry out the present study was obtained from the Ethical commit-tee of the Ministry of Public Health of Cameroon, the Ministry of Higher Education and local authorities. Ethical clearance and approval was obtained from the Ethical committee of the Ministry of Public Health of Cameroon. Approval permission and written consent were obtained from the headmasters at the school (the guardian of pupils according to the Cameroonian context while in school) and from each of the adolescents prior to the study. Confidentiality was ensured and participants had the right to withdraw from the study whenever they wanted.

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objectives

General objectiveTo assess dietary intake, anthropometry and physical activity of adolescents accord-ing to sex and socioeconomic status (SES), and to investigate food perception of adolescents living in urban and rural areas in Cameroon.

Specific objectives- To describe and compare the food habits and nutritional status of adolescents in urban and rural areas in Cameroon (paper I).- To investigate factors influencing adolescents’ food perceptions in the context of the nutritional transition occurring in Cameroon (paper II).- To assess nutritional status of adolescents according to sex and SES in urban Cam-eroon by using anthropometry (paper III).- To assess energy and nutrient intake as well as physical activity of adolescents ac-cording to sex and SES in urban Cameroon (paper IV).

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methods

Study areas and population

Figure 2. Map of Cameroon showing the location of the study areas, Yaoundé and Bandja.

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Methods

Study areas and population

Figure 2. Map of Cameroon showing the location of the study areas, Yaoundé and Bandja.

Bandja

Yaoundé

MeThODs

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YaoundéYaoundé is the capital city of Cameroon. It is located in the centre province and has more than 2.5 million inhabitants and a land area of 297 km². The primary occupation of the people in Yaoundé is mostly white-collar workers, entrepreneurs and students. Yaoundé has one of the best equipped hospitals in the country, several public hospitals and private clinics. The main diseases are malaria, respiratory diseases, hypertension, obesity and cardiovascular diseases. Houses are made of cement blocks, bricks or shaped stones with a roof made of cement, zinc or tile (4, 15). Housing equipment is characterized by cooking with gas (45%) and open fire using wood, television, radio (81%), mobile phone (10%) and car (4). About 22% of the population use water closet, electricity coverage is 97% and water supply at home 90%. Food supply is mostly from open market. People most often eat breakfast composed of left over food or a western breakfast with bread and hot drink, lunch and dinner. Food and meals diversities depend on the economy of the household. Yaoundé is characterized by areas with different SES (low, middle and high) and there is a vast disparity in income distribu-tion between people in Yaoundé (Gini index is 0.43) as well as overall in Cameroon (Gini index is 0.45) (4, 30).

BandjaBandja is a rural area located in the western province with 8621 inhabitants and a land area of 62 km²(31). The primary occupation of the people of Bandja is farming. There is one district hospital in Bandja. The main diseases in Bandja are malaria, respiratory and diarrheal diseases and hypertension (31). Housing walls are made of shaped stone with roof made of zinc or grass. The kitchen is a small room out of the house with a window, a door, open fire with wood and loft. The toilet is a hole made in the ground outside the house (latrine). There is no electricity or water supply at home. Water supply comes from public taps, wells and rivers. The main staple food is cassava, maize, cocoyam, plantain, beans, green leaves sauce and groundnut sauce. Food is supplied by subsistence farming. People eat mostly breakfast composed of left over food and dinner.

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MeThODs

Figure 3. Classroom and pupils in Bandja.

SamplingSampling for paper IIn the Bandja rural area one school situated in a remote quarter was selected. There were only two classes in that school in Bandja- grade one with one class and grade two with one class. All adolescents (grade two) who were present at the time of the study were included (12 boys and 14 girls); the same number of adolescents in grade two was randomly selected from a school in Yaoundé (13 boys and 13 girls).

Sampling for paper IIFor paper II the most talkative students in each school from the previous paper were selected from Bandja (2 boys and 3 girls) and Yaoundé area (3 boys and 2 girls). A third school was randomly selected in Yaoundé from an area characterized with high SES and the most talkative students were selected from one randomly selected grade two class (2 boys and 3 girls).

Sampling for paper IIISample size was estimated using n-Query version 1 and the power was set to 80% and the significance level at p< 0.05. Six hundred boys and girls, 12-16 years of age, were randomly selected from grade two from public secondary schools in Yaoundé. The randomization was made in two steps. Firstly, three schools were randomly se-lected from three areas characterized by different socioeconomic levels. One school was located in an area characterized by low SES, another in an area with middle SES and the third from an area with high SES. Secondly, classes were randomly selected within each school and 200 students were selected (from each school) for the study. Adolescents were healthy at the time of data collection as assessed by a physician, except 2 girls, one with type 1 diabetes and one with sickle cell anemia. In total nine-teen pupils were excluded because of diseases, out of the age span, inaccurate data and absent from school at the time of data collection. Thus, in total 581 pupils were included (248 boys and 333 girls).

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Sampling for paper IVFor paper IV, one class comprising approximately 80 adolescents was randomly se-lected from each of the three schools participating in paper III. From every class all students present during the data collection were included. In total, 227 adolescents participated (108 boys and 119 girls).

Study personnelThe total study personnel taking part in the data collection consisted of one physi-cian, one public health professional specialized in dietetic (author), one dietician, three school nurses, one assistant nurse, two medical students and five university students. All study personnel had undergone one week of training by the author for the assessment procedures. Their participations varied according to each paper.

Data collectionThe present studies were cross-sectional. Data were collected at the school by the study personnel in 2004 (papers I and II) and in 2006 (papers III and IV). Data collection included background questionnaire, food frequency questionnaire, 24-hour dietary and physical activity recalls, anthropometric measurements and qualitative interviews. The participants received pens, pencils and textbooks as incentives. The schools were promised to be given feedback as well as nutritional education by the author. A pre-testing pilot study on similar adolescents was done in 2004 before the study.

Background questionnaire (papers I–IV)Information about name, age, sex, household chores, leisure time activity, exam grade, bring lunch food from home food or buy food at school, district of habitation, equipment at household level, water and electricity sources, mode of transport, number of persons per room, parents’ occupations and student’s daily pocket money was collected. Instructions were given by the author and the school nurses to the adolescents before and when they filled in the questionnaire. Health status and pu-berty were determined by a physician. Socioeconomic status (low, middle, high) was determined using a classification system from the National Institute of Statistics of Cameroon based on district of habitation, equipment at household level, number of persons per room and parents’ occupations (4, 29).

Qualitative method (paper II)Interview questions were developed by the author and a collaborating researcher in qualitative methods. First, participant observation in school was used to find out which questions to include in the study. Then, questions were pilot-tested by using focus group discussions with other adolescents of the same age from urban and rural areas. From this pilot-testing, a study theme was generated. Thereafter other focus group discussions were done with other adolescents to test the study theme. Finally in-depth-interviews were conducted to get a deeper investigation of adolescents’ food perception. A thema-tized interview guide with semi-structured questions was used to ensure consistency

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and to allow every informant to expand his or her thinking. Interviews were focused on food preferences, views and on the relationships between food and diseases. The relationship between food and nutrients was also in focus. Examples of questions were; “can you describe your food habits?” “what do you like to eat?”, “what does food mean to you?”, “ what can you get from milk” “what can you get from fruits?”, “what can you get from green leafy vegetables?”, “what can you get from oil”, “what can you get from fish”, “what can you get from meat?”, “what can you get from rice?”, “what can you get from cassava, plantain, cocoyam, maize?”, “what can you get from doughnuts, candies, sweet beverages?”, “how does one prevent weight problems, diabetes, cardio-vascular diseases, stroke, hypertension?”, “what is anemia?”, “how does one prevent anemia or vitamins or minerals (calcium, iodine, zinc) deficiencies?”. The adolescents were individually interviewed to a point that both the interviewer and the adolescent felt that the themes were covered and that no new information was obtained about the adolescents’ food perceptions. The interviews were conducted at school during free time in the classroom or the nurse office by the author with a nurse and an assistant nurse as note-takers. Each interview took approximately 45 minutes.

Anthropometry and puberty assessments (papers I, III and IV)Body weight (kg) was measured to the nearest 0.1 kg using an electronic scale (Seca model 826). Pupils were measured in the morning wearing light clothes and no shoes. Standing height (cm) was measured to the closest 0.1 cm using a portable stadiometer (Seca) made from a tape-measure fixed to the wall and headpiece equipped with a level to ensure a 90 degree. From these measurements body mass index (BMI, kg/m²) was calculated. Mid Upper Arm Circumference (MUAC, cm) was measured at the mid-right upper arm using a small tape, and Triceps Skin fold thickness (TSF, mm) at the same location using a calliper (John Bull British model). Arm Muscle Area (AMA, mm²) and Arm Fat Area (AFA, mm²) were calculated using a formula derived from MUAC and TSF (17).

Waist circumference (cm) was measured between the lowest rib and the iliac crest and Hip circumference (cm) at the level of the greater trochanters between the waist and the knees; the measurements were made to the nearest cm using a flexible tape. Thus, Waist Hip Ratio (WHR) was calculated. The author made all the MUAC, TSF and hip measurements.

Puberty was determined based on menarche in girls, and on pubic/armpit hair, night ejaculation, intercourse and voice changing in boys by the physician.

Dietary intake assessmentFood frequency questionnaire (papers I and III)A food frequency questionnaire (FFQ) was used to assess the food pattern of the adolescents over the past month. The FFQ was developed by the author and two nutritionists inspired by information from a nutritional epidemiology book, a FFQ used to assess food habits among adults in Cameroon, and a questionnaire from the

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WHO/HBSC (17, 32-34). Focus group discussions with adolescents, parents, vendors and school nurses were used to obtain information about the most commonly con-sumed food to be included in the FFQ. The FFQ consisted of 54 food items including cassava (Manihot esculenta), cassava bread, cassava/maize porridge, plantain (Musa paradisiaca), unripe bananas, potatoes, yam (Dioscorea spp), cocoyam (Xanthosoma spp), rice, pasta, beans, meat, fish, eggs, beans cake, groundnuts/tomatoes sauce, okok (Gnetum spp), ndolé (Vernonia amygdalina), gombo (Abelmoschus esculentus), egguci (Cucurbita pepo), safou (Dacryodes edulis), fruits, milk, kossam (home made yoghurt), bread, doughnuts, candies, biscuits, chocolate, chips, pastry and soft drinks. Frequencies and information about breakfast, lunch and dinner and in-between meal were also collected. The FFQ was self-reported by asking adolescents how many times per week they consumed each of the food items listed. The FFQ was done in the classroom. No information about the amount of consumption was collected.

24-hour dietary recall (paper IV)The information about the adolescents’ retrospective food intake covered three days in total. The adolescents were asked to recall the actual food and drink consumed during the immediate past days and the order of recall was commenced with the first food or drink consumed that specific day. Individual interviews with each adolescent lasting approximately 45 minutes were conducted in the classroom or school nurse office by study personnel.

Figure 4. Interview of 24-hours dietary recall and example of some traditional foods, cassava bread and folong, cassava porridge and gombo sauce with dry fish, and taro with palm oil sauce and fried fish.

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A color picture booklet of different portion sizes including weight was developed by the author to help the adolescents to estimate the amount of food consumed (Appendix). The booklet included 68 pictures of the most common foods such as cassava, plantain, unripe bananas, potatoes, yam, cocoyam, cassava porridge, maize porridge, rice, pasta, different kinds of green leafy vegetables sauce (okok, ndolé, gombo, folong) groundnut/tomatoes sauces, egguci, beans, beef, chicken, dry fish, fresh fish and cake. Each food or meal was displayed in three pictures representing three different portion sizes.

Household measures (spoon, glass, plate), real food portions and information about the amount of money spent on some foods (bread, maize porridge, cas-sava bread, doughnuts, papaya, pineapple, bananas, orange) and drinks (coca-cola, sprite), foléré (sweet beverage with rosell red fruits), kossam (home made yoghurt with milk and sugar) were also used to estimate the amount of food eaten. For food such as candies, chocolates and biscuits, information about the weight per item was obtained from the labeling. The weight of reported cooked food items eaten at home was estimated by the author who weighed portions of similar food items prepared or bought. Information about ingredients in different meals, product prices and type of fat/oil used was obtained from vendors, restaurants and from girls (as they most often were responsible for the cooking together with their mothers).

The reported food intake was converted into grams per day, and the content of en-ergy, macronutrients and some micronutrients were calculated using Becel Institution Nutrition Software version 3.0 (BINS) (35). When a specific food item reported eaten by the adolescents was missing in the data base information from food composition tables of Mali and Africa was used to obtain data about nutritional content (36, 37). The nutrient content information from these sources was incomplete for four main staple foods (cassava bread, cassava porridge, cassava tuber and ripe plantain). Laboratory nutrient analyses were therefore performed by an accredited laboratory (Eurofins, Sweden).

Physical activity assessment (paper IV)Information about the type and duration of physical activities undertaken by the adolescent was collected together with the dietary interviews, providing data of three days of physical activities in total. Metabolic energy turnover (MET) factors were assigned to each type of activity reported and then multiplied with the duration of the activity to calculate the contribution to reported energy expenditure (EErep). The EErep was calculated as the sum of the energy expenditure from each activity conducted during 24 hours, divided by 24 hours and multiplied by the calculated basal metabolic rate (BMRcal) for each individual. To obtain BMRcal for each adolescent Schofield equation based on sex, age, individual body weight and height was used (25, 38). A physical activity level (PAL=EErep/BMRcal) was calculated for each adolescent and was thereafter used to classify the adolescents as having either low, moderate, or high PAL, according to the cut-off value described by FAO/WHO/UNU (38).

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Identifying mis-reporters of energy intake (paper IV)In order to determine whether reported energy intake (EIrep) was plausible as a valid measure of food intake and to identify under-reporters and over-reporters, Goldberg’s cut-off method was used and confidence limits (CL) of agreement between EIrep/BMRcal and PAL were calculated (25, 39). Adolescents with a ratio (EIrep/BMRcal) below the lower confidence limit were regarded as under-reporting and those above the upper limit as over-reporting of food intake (25, 39).

Data analysisIn paper I the body weight and AMA were compared with data from the US and WHO/FAO references (17, 40).

In paper II, qualitative interviews were recorded, transcribed and analyzed using Grounded theory method. Grounded theory is a qualitative research method used to studying social phenomena from the perspective of human behavior (41). Grounded theory was used to increase understanding of factors influencing adolescents’ food perceptions. Data analysis was done for each informant for each area. Data were coded for each informant by using key phrases in the informant’s own words. Then similar key phrases were grouped into sub-categories, and these sub-categories were used to identify categories presented in a theoretical model in figure 5.

In Papers I and III the International cut-off BMI-for-age in adolescents as defined by Cole et al was used to define overweight, and the age and sex specific BMI less than the fifth percentile from the US-CDC was used to defined underweight (25, 42). Overweight includes both overweight and obesity. Height-for-age and sex less than the fifth percentile from the US-CDC was used to define stunting (25).

In paper IV, acceptable macronutrients distribution ranges (AMDR), recom-mended dietary allowance (RDA) and estimated average requirement (EAR) were used to determine adequacy of nutrient intake (for macronutrients expressed as percentage below or above the AMDR and for micronutrients as percentage below the EAR, between the EAR and RDA and above RDA) (25, 43-45). AMDR is defined as the range of intake for a particular energy source associated with reduced risk of chronic diseases while providing adequate levels of essential nutrients (25). AMDR is 10-30%, 45-65%, 25-35% of total energy intake (E%) for protein, carbohydrates and fat, respectively. RDA is the average daily nutrient intake level estimated to meet the requirement of nearly all healthy individuals in a particular life stage and sex. EAR is the average daily nutrient intake level estimated to meet the nutrient require-ment of half the healthy individuals in a particular life stage and sex (45). The EAR for adolescents is derived from a formula based on the EAR for adults, weight of the adolescents, weight of adults and a growth factor (44).

Statistical analysisData entry, checking and processing was done by the author with some help with data entry from two of the university students. Data were analyzed using SPSS versions 11 and 15 and the level of significance was set at p-value <0.05.

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The results are presented as means with standard deviations, medians with 25th and 75th percentiles (in brackets), and percentages. Comparisons between urban and ru-ral adolescents and between boys and girls were analyzed using Student’s t-test and Mann-Whitney test for normally distributed and skewed data, respectively. Univariate ANOVA and Kruskal-Wallis tests were used for comparisons between low, middle and high SES for normally distributed and skewed data, respectively. Correlations between anthropometric variables were calculated. Frequencies of consumption of food groups and meals by sex, SES and urban/rural were calculated. Differences in proportion were analyzed using Chi-square test.

The proportions of adolescents stunted, underweight and overweight by urban/rural areas, sex and low, middle and high SES were calculated and differences were analyzed using Chi-square test. Logistic regression was used to investigate the rela-tionships between sex, puberty, SES and overweight, underweight or stunting.

The proportion of adolescents doing different types of activity was calculated and differences were analyzed using Chi-square test.

Differences in proportion between the adolescents below and above requirements for macronutrients as well as micronutrients were analyzed. The proportion of mis-reporting of EI was calculated and differences between PAL-groups were analyzed using Chi-square test.

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resuLtsCharacteristics and physical activity of adolescentsIn paper I there were 12 boys and 14 girls living in the urban area, and 13 boys and 13 girls living in the rural area. The median daily pocket money was 200 {138-300} Fcfa among the urban adolescents vs. 100{25-200} Fcfa among the rural adolescents (p<0.001) (1Euro=656Fcfa). Three out of 26 urban adolescents and four out of 26 rural adolescents brought their lunch from home to school (p=0.692). The mean exam grade was 11.3 ± 0.8 in the urban area vs. 10.1 ± 1.8 in the rural area, (p=0.001). The maximum exam grade to pass is 20 out of 20.

In paper II there were 2 boys and 3 girls living in the rural area, 3 boys and 2 girls living in the urban area with low SES, and 2 boys and 3 girls living in the urban area with high SES. These adolescents were selected from the participants in paper I.

The urban adolescents included in papers I and II had television, telephone, stove, tap water and electricity supply at home, and they went to school by parental car or motorcycle taxi (data not shown). In contrast, the rural adolescents had no television, no telephone, open fire with wood instead of stove, water from public tap instead of tap water at home, oil lamp instead of electricity and they walked a long distance to school during school days and to farms during weekend (data not shown). Urban adolescents described their leisure time activities as watching television, listening to music, cleaning, washing, resting, sleeping and playing football. In contrast, rural adolescents described their lei-sure time activities as farming, carrying water, dishing, sweeping, washing, cooking food and playing football. Girls were engaged in cooking and boys in playing football.

In paper III there were 248 boys (100 low, 114 middle and 34 high SES) and 333 girls (159 low, 132 middle and 42 high SES). There was no significant difference in daily pocket money between boys and girls (p=0.878). The median daily pocket money was 150{100-200}Fcfa vs. 200{150-500}Fcfa vs. 500{213-600}Fcfa among the adolescents with low, middle and high SES, respectively (p< 0.001).

There was no difference between boys and girls regarding buying food or bring-ing food from home to school. However, 13% of the adolescents with low vs. 22% of those with high SES brought food from home to school, while 83% vs. 78% bought food at school, and 4% vs. 0% did not eat at all, in the low and high SES, respectively (p= 0.006). The mean exam grade among the adolescents with low and high SES was 11.1 ± 1.7 vs. 11.5 ± 1.6, respectively (p=0.040), however, no significant difference was found between boys and girls (p=0.725). There were no significant differences between boys and girls regarding activities, however among the adolescents with low, middle and high SES, 28% vs. 36% vs. 53% reported watching television, and 40% vs. 30% vs. 24% reported doing household chores, respectively (p=0.002).

In paper IV there were 108 boys and 119 girls included who were selected from the participants in paper III. Of these 94 adolescents had low SES, 105 had middle SES and 28 had high SES. Overall, girls spent more time on light activities such as doing homework, cooking, sitting and praying, while boys spent more time playing football

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and playing other games. The differences between boys and girls regarding activities were largest during the weekend but significant only for time playing football and cooking (p <0.001). Sixty-six percent of boys vs. 10% of girls reported playing foot-ball, while 12% of boys vs. 42% of girls reported cooking. Adolescents with low SES reported spending less time eating than adolescents with high SES (88± 26 vs. 102 ± 28 minutes/day p = 0.007, respectively). Seventy-four percent of adolescents with low SES vs. 78% of those with middle SES vs. 80% of those with high SES reported using car transportation (p =0.445).

Anthropometry and puberty of adolescentsThe urban adolescents in paper I were significantly younger than those from the rural area (12.7 ±0.7 vs. 13.7 ±1.1 years, respectively, p=0.001). Among boys 31% in the urban area vs. 36% in the rural area had reached puberty (p=0.772). In the urban area 39% of the girls had reached puberty vs. 13% in the rural area (p =0.126). Urban adolescents had significantly lower MUAC, AMA, waist and WHR than the rural adolescents (Table 1). There was a positive significant correlation between BMI and AMA in urban adoles-cents (r= 0. 720, p< 0.01) and in rural adolescents (r= 0.670, p<0.01). The proportion of the adolescents above the WHO reference for weight was almost twice as high in the urban area compared to the rural area (42% vs. 23%, respectively, p= 0.037).

table 1. Anthropometrics of urban and rural adolescents (paper I)1.

Urban low SES(N=26)

Rural(N=26)

P

Weight (kg) 45.3 ± 8.5 47.9 ± 8.1 0.268Height (cm) 152.2 ± 9.3 152.9 ± 8.4 0.756BMI (kg/m2) 19.4 ± 2.1 20.6 ± 1.8 0.096MUAC (cm) 21.9 ± 2.3 24.1 ± 2.1 0.001TSF (mm) 10.1 ± 4.8 9.8 ± 3.2 0.801AMA (mm2) 2802 ± 474 3554 ± 614 <0.001

AFA (mm2)1052 ± 567

884 {564-1413}1121 ± 390

1171{763-1515}0.337

Waist (cm) 66.0 ± 5.6 70.3 ± 4.7 0.004Hip (cm) 82.7 ± 6.8 85.2 ± 6.2 0.164WHR 0.79 ± 0.03 0.82 ± 0.04 0.004

Data are given as mean ± SD and median with 25th-75th percentiles in brackets. 1Differences between urban and rural adolescents were analyzed using student’s t-test except for AFA which was tested using Mann-Whitney. BMI: body mass index, MUAC: mid upper arm circumference, TSF: triceps skinfold thickness, AMA: arm muscle area, AFA: arm fat area, WHR: waist hip ratio.

The adolescents included in paper II were 13 to 14 years of age (qualitative study).The means age for boys and girls in paper III were 13.4 ± 0.9 and 13.5 ± 0.9 years

for boys and girls, respectively, (p= 0.374), and 13.6 ± 0.9 vs. 13.4 ± 0.9 vs. 13.3 ± 0.9 years among adolescents with low, middle and high SES, respectively, (p=0.083). Among boys and girls, 41% vs. 62% had reached puberty, respectively, (p< 0.001) but no significant difference was found between the adolescents with low, middle and high SES (p=0.943). In the urban area, boys had significantly lower anthropometric variables than girls except for AMA and WHR (Table 2).

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table 2. Anthropometry of adolescents by sex in Yaoundé (paper III) 1.

Boys(N=248)

Girls(N=333)

P

Weight (kg) 45.6 ± 9.1 51.4 ±10.4 < 0.001Height (cm) 156.8± 10.3 157.8 ± 6.7 0.074BMI(kg/m2) 18.4 ± 2.1 20.4 ± 2.7 < 0.001MUAC(cm) 22.6 ± 2.5 24.7 ± 4.0 < 0.001

TSF(mm)8.2 ± 3.4

7.5{6.4-9.0}15.6 ± 6.0

14.5{11.0-19.0}< 0.001

AMA(mm2) 3245 ± 749 3096 ± 615 0.021

AFA(mm2)884 ± 446

770{662-982}1750 ± 795

1575{1190-2176}< 0.001

Waist(cm) 67.4 ± 5.7 71.6 ± 6.5 < 0.001Hip (cm) 81 ± 7.4 89.7 ± 8.0 < 0.001WHR 0.83 ±0.07 0.79 ± 0.05 < 0.001

Data are given as mean ± SD and median with 25th-75th percentiles in brackets. 1Differences were analyzed using Mann-Whitney test for TSF and AFA and for all other variables Student’s-test was used.BMI: body mass index, MUAC: mid upper arm circumference, TSF: triceps skin fold thickness, AMA: arm muscle area, AFA: arm fat area, WHR: waist hip ratio.

The adolescents with high SES were significantly taller and had lower WHR than those with low SES (Table 3).

The mean ages for boys and girls in paper IV were 13.4 ± 0.9 years and 13.5 ± 0.9, respectively (p= 0.264) and among the adolescents with low, middle and high SES 13.5 ± 0.9 vs. 13.4 ± 0.9 vs. 13.3 ± 0.9 years, respectively (p=0.001).

table 3. Anthropometry of adolescents by socioeconomic status (low, middle, high) in Yaoundé (paper III)1.

Low(N=259)

Middle(N=246)

High(N=76)

P

Weight (kg) 47.9 ± 9.0 49.3 ± 12.0 50.0 ± 8.8 0.168Height (cm) 156.0 ± 8.0 158.0 ± 8.4 158.8 ± 9.0 0.027BMI(kg/m2) 19.6 ± 2.6 19.4 ± 2.9 19.7 ± 2.4 0.727MUAC(cm) 23.6 ± 3.0 23.9 ± 4.4 23.8 ± 2.5 0.645

TSF(mm)12.6 ± 6.1

11.0{8.0-15.5}12.3 ± 6.7

10.1{7.2-16.0}12.1 ± 5.3

11.0{8.0-15.6}0.412

AMA(mm2) 3106 ± 723 3156 ± 638 3211 ± 603 0.457

AFA(mm2)1390 ± 765

1181{809-1692}1383 ± 869

1079{751-1762}1349 ± 670

1152{823-1753}0.493

Waist(cm) 69.54 ± 6.20 69.86± 6.98 70.04 ± 6.10 0.788Hip (cm) 85.53 ± 8.52 85.80 ± 9.39 87.62 ± 8.41 0.199WHR 0.81 ± 0.05 0.81 ± 0.06 0.80 ± 0.08 0.035

Data are given as mean ± SD and median with 25th-75th percentiles in brackets. 1Differences were analyzed using Kruskal-Wallis test was used for TSF and AFA and for all other variables uni-variate ANOVA test was used.BMI: body mass index, MUAC: mid upper arm circumference, TSF: triceps skin fold thickness, AMA: arm muscle area, AFA: arm fat area, WHR: waist hip ratio.

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Stunting, underweight and overweight In paper I the proportion of stunting was equal among the urban and rural adolescents (15%). No adolescent was underweight either in the urban or rural areas. There was no significant difference between the urban and rural areas adolescents regarding the proportion of overweight (8% vs. 12%, respectively, p= 0.638).

In total, 9% of the adolescents in paper III were stunted, 3% were underweight and 10% were overweight. The proportion of stunting was three times higher in boys compared to girls (p<0.001) (Table 4). The proportion of underweight was six times higher in boys compared to girls, but the proportion of overweight was three times lower in boys compared to girls (p<0.001) (Table 4). Girls were less likely to be stunted and underweight than boys (OR: 0.29, p<0.001; OR: 0.20, p<0.01, respectively). Girls were four times more likely to be overweight than boys (OR: 4.13, p<0.001).

The proportion of stunting was two times lower among the adolescents with high SES compared to those with low SES (p=0.033) (Table 4). No difference was found among the adolescents with high, middle and high SES regarding the proportion of underweight (p=0.467) and overweight (p=0.542) (Table 4). Adolescents with high SES were less likely to be stunted than those with low SES (OR: 0.40, p<0.01).

table 4. Prevalence of stunting, underweight and overweight by sex and socioeconomic status (low, middle, high) in Yaoundé (paper III)1.

Sex Socioeconomic statusBoys

(N = 248)Girls

(N = 333)Low

(N = 259)Middle

(N = 246)High

(N = 76)Stunting2 15a 5a 12c 6c 5c

Underweight3 6b 1b 3d 4d 1d

Overweight4 4a 14a 8d 11d 9d

Data are given as percentage (%). 1Differences between boys and girls, and between low, middle and high SES were analyzed using Chi-square test.2Stunting as defined by height-for-age <5th percentile.3Underweight as defined by BMI-for-age <5th percentile.4International BMI for overweight of adolescents as defined by Cole et al (42).ap<0.001, bp=0.002, cp=0.033, dp>0.05.

Adolescents’ food perceptionRural adolescents ate in order to live and to maintain health, but because of lack of money they could not buy food at school (Figure 5). At home, they ate because of hunger and in order to be filled-up, to get energy, avoid diseases and to live. They knew from their teacher and fathers that food gives vitamins and strength and that alcohol destroys the brain. For them food can give dysentery if not well cooked. They liked doughnuts, stew and beans because they were good and sweet. Girls preferred to be fat and not slim like a model.

Urban adolescents with low SES ate in order to maintain health. They ate in order to grow, get strength and energy. They wanted to grow in order to become respected

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and free adults. But they said that they do not always have enough money to buy food at school. They said that that they eat food that does not make them heavy and tired. They knew that food gives vitamins and said that alcohol makes parents and adults irresponsible, mad, destroys the body, and gives cancer and hypertension. They liked “tasty” foods like rice, plantain, meat, bread, candies and soft drinks. Girls preferred to be a bit fat.Urban adolescents with high SES ate for pleasure. In the urban area with high SES the adolescents knew that food gives vitamins, energy and strength and they ate to grow, avoid diseases and to live. They also said that alcohol makes parents nervous and do bad things. They liked doughnuts, candies, chips, tomato sauce, bread pastry, beans cassava and sauce made from green leafy vegetable mixed with groundnuts and palm oil. They said that food was available from home or vendors. Girls wished to be normal weight and look nice.

Figure 5. A model of factors influencing food perceptions of adolescents (paper II).

Food intake and meals patternRural adolescents reported a significantly lower consumption frequency of seven out of ten food groups (Table 5). Eggs and milk products were five times more consumed by the urban than the rural adolescents.

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table 5. Food frequency consumption of different food groups per week in urban and rural areas (paper I)1.

Urban low SES(N=26)

Rural(N=26)

P

Bread and sandwiches5.7 ± 1.8

7.0 {3.75-7.0}2.2 ± 2.4

2.0{0-3.0}<0.001

Meat and fish11.8 ± 5.2

12.0 {8.0-13.3}4.5 ± 2.9

4.5 {2.3-5.0}<0.001

Eggs3.7 ± 2.1

3.0{2.0-5.0}0.6 ± 1.00{0-1.0}

<0.001

Green leafy vegetables and tomatoes

9.5 ± 3.78.5{7.0-11.0}

3.9 ± 2.44.0 {2.0-6.0}

<0.001

Junk food2 22.6 ± 10.921.5{14-32}

6.7 ± 2.97.0{4.0-8.0}

<0.001

Rice and pasta6.5 ± .2.9

6.5{4.0-9.0}3.8 ± 2.0

3.0{2.0-5.0}<0.001

Beans and nuts7.6 ± 4.3

7.5{4.0-10.0}9.3 ± 3.3

9.0{6.0-12.0}0.130

Milk products5.7 ± 3.4

5.0 {2.75-8.0}0.8 ± 1.70 {0-1.0}

<0.001

Plantain, roots and maize3 10.6 ± 4.89.0{7.8-14.0}

9.2 ± 5.48.5{5.0-12.8}

0.276

Fruits11.0 ± 5.2

9.5{7.0-15.0}8.9 ± 4.4

8.0{6.3-10.0}0.189

Data are given as mean ± SD and median with 25th-75th percentiles in brackets. 1Differences between urban and rural adolescents were analyzed using Mann-Whitney test. 2Junk food comprises doughnuts, cake, biscuits, chips, candies, chocolate and sweet beverages.3Plantain, roots and maize comprises plantain, cocoyam, yam, cassava, maize and cassava porridge, potatoes, sweet potatoes and unripe banana.

Urban adolescents significantly more often reported eating lunch and had five times higher consumption frequency of in-between meals than the rural adolescents (Table 6). In contrast, the rural adolescents more often ate breakfast compared with urban adolescents (paper I).

table 6. Frequency of meals consumption per week in urban and rural areas (paper I)1.

Urban low SES(N= 26)

Rural(N= 26)

P

Breakfast5.0 ± 2.3

6.0{2.0-7.0}6.7 ± 1.1

7.0{7.0-7.0}0.005

Lunch6.1 ± 2.1

7.0{2.0-7.0}5.0 ± 2.1

5.0{3.0-7.0}0.031

In-between meal4.9 ± 2.3

5.0 {2.0-7.0}0.9 ± 1.40 {0-2.0}

<0.001

Dinner6.5 ± 1.7

7.0{7.0-7.0}6.6 ± 1.6

7.0 {7.0-7.0}0.886

Data are given as mean ± SD and median with 25th-75th percentiles in brackets.1Differences between the urban and rural adolescents were analyzed using Mann-Whitney test.

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ResULTs

Boys reported a significantly lower consumption frequency of six out of ten food groups than girls (Table 7). This difference between boys and girls was largest for junk food consumption. Water consumption was reported every day by all the adolescents.A significantly lower proportion of boys reported eating in-between meals compared to girls (Table 8). More than 30 % of the adolescents (both boys and girls) reported skipping breakfast during school days.

table 7. Food frequency consumption of different food groups per week by sex in Yaoundé (paper III)1.

Total(N = 581)

Boys(N = 248)

Girls(N = 333)

P

Bread and sandwiches

4.9 ± 1.95.0 {3.0-7.0}

4.9 ± 1.95.0 {3.0-7.0}

5.0 ± 2.05.0{3.0-7.0}

0.605

Meat and fish 5.0 ± 2.7

4.0{3.0-6.5}4.8 ± 2.6

4.0 {3.0-6.0)5.1 ± 2.8

5.0{3.0-7.0}0.055

Eggs2.8 ± 2.4

2.0{1.0-4.0}2.6 ± .2.1

2.0 {1.0-4.0}3.0 ± 2.3

2.0{1.0-4.0}0.020

Green leafy vegeta-bles and tomatoes

5.0 ± 3.05.0{3.0-7.0}

4.7 ± 3.04.0 {3.0-7.0}

5.2 ± 3.05.0{3.0-7.0}

0.032

Junk food2 20.2 ± 9.720 {13-27}

17.9 ± 9.117 {11-23}

22.0 ± 9.821{15-28}

< 0.001

Rice and pasta5.1 ± 2.6

4.0{3.0-6.0}4.8 ± 2.5

4.0{3.0-6.0}4.9 ± 2.7

4.0 {3.0-6.0}0.929


4.0{3.0-7.0}5.4 ± 3.0

5.0{3.0-7.0}4.8 ± 2.7

4.0{3.0-6.0}0.006


3.0{1.0-7.0}3.6 ± 3.2

2.0{1.0-7.0}4.4 ± 3.9

3.0{1.0-7.0}0.023

Plantain, roots and maize3

8.1 ± 4.57.0{5.0-10.0}

7.6 ± 4.47.0{5.0-10.0}

8.4 ± 4.68.0{5.0-11.0}

0.019

Fruits5.1 ± 4.7

4.0{2.0-7.0}4.6 ± 4.5

4.0{1.0-7.0}5.5 ± 4.8

4.0{2.0-7.0}0.010

Data are given as mean ± SD and median with 25th-75th percentiles in brackets.1Differences between boys and girls were analyzed using Mann-Whitney test. 2Junk food comprises doughnuts, cake, biscuits, chips, candies, chocolate and sweet beverages. 3Plantain, roots and maize comprises plantain, cocoyam, yam, cassava, maize and cassava porridge, potatoes, sweet potatoes and unripe banana.

During weekends consumption frequency of breakfast increased with increasing SES (p=0.009) (Table 8). Consumption frequency of in-between meal also increased with increasing SES; about two third of the adolescents with high SES ate in-between meals compared to half of those with low SES (p<0.001).

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28

table 8. Proportion of adolescents having different meals by sex and socioeconomic status (low, middle, high) in Yaoundé (paper III)1.

Sex Socioeconomic statusBoys

(N=248)Girls

(N=333)p

Low(N=259)

Middle(N= 246)

High(N=76)

p

Breakfast school days

67 69 0.653 65 69 75 0.246

Lunch school days

83 86 0.319 83 85 87 0.586

Dinner school days

98 98 0.842 97 99 100 0.134

Breakfast weekend

92 90 0.393 87 93 98 0.009

Lunch weekend

93 91 0.299 91 91 97 0.160

Dinner weekend

98 97 0.466 98 97 98 0.927

In-between meal

41 67 <0.001 48 63 62 <0.001

Data are given as percentage (%).1Differences between boys and girls were analyzed using Chi-square test.

Figure 6. Vendors of junk food within the school yard in Yaoundé.

Consumption frequency of different food group significantly increased with increasing SES. Egg was two times more frequently consumed by the adolescents with high SES compared to those with low SES (Table 9). Junk food was significantly more often consumed by the adolescents with high SES compared to those with low SES. Milk products were more than three times more often consumed by the adolescents with high SES compared to those with low SES (Table 9).

29

ResULTs

table 9. Food frequency consumption of different food groups per week by socioeconomic status (low, middle, high) in Yaoundé (paper III)1.

Socioeconomic statusLow

(N=259)Middle

(N =246)High

(N=76)P

Bread and sand-wiches

4.6 ± 2.05.0{3.0-7.0}

5.1 ± 1.96.0{3.0-7.0}

5.6 ± 1.86.0{5.0-7.0}

<0.001

Meat and fish4.4 ± 2.5

4.0{3.0-6.0}5.4 ± 2.8

5.0 (3.5-7.0}5.6 ± 2.9

5.0{3.0-8.0}<0.001

Eggs2.4 ± 2.0

2.0{1.0-3.0}3.0 ± 2.3

3.0{1.0-7.0}3.9 ± 2.4

4.0{2.0-7.0}<0.001

Green leafy vegeta-bles and tomatoes

4.5 ± 2.94.0{2.0-7.0}

5.6 ± 3.05.0{3.0-7.0}

5.3 ± 3.15.0{3.0-7.0}

<0.001

Junk food2 17.9 ± 9.217{11-23)

21.5 ± 9.221 {15-28)

24.4 ± 10.924{16-32}

<0.001

Rice and pasta4.6 ± 2.5

4.0{3.0-6.0}5.1 ± 2.6

5.0{3.0-6.5}5.1 ± 2.8

4.0{3.0-7.0}0.048


4.0{3.0-7.0}5.3 ± 3.0

5.0{3.0-7.0}4.6 ± 2.8

4.0{2.0-6.0}0.148


2.0{0-5.0}4.8 ± 3.6

4.0{2.0-7.0}6.1 ± 3.7

7.0{2.0-8.0}<0.001

Plantain, roots and maize3

8.0 ± 4.47.0{5.0-11.0}

8.2 ± 4.78.0{5.0-10.}

7.8 ± 4.47.0{5.0-10.0}

0.870

Fruits4.3 ± 4.1

3.0{1.0-6.0}5.4 ± 4.5

4.0{2.0-7.0}6.7 ± 6.4

5.0{2.0-9.0}<0.001

Data are given as mean ± SD and median with 25th-75th percentiles in brackets.1Differences between low, middle and high SES were analyzed using Kruskal-Wallis test. 2Junk food comprises doughnuts, cake, biscuits, chips, candies, chocolate and sweet beverages. 3Plantain, roots and maize comprises plantain, cocoyam, yam, cassava, maize and cassava porridge, potatoes, sweet potatoes and unripe banana.

Energy and nutrient intake of adolescentsOver 55% of the adolescents were below 10 E% for protein, 26% were below 25 E% and 25% above 35 E% for fat, and 7% were below 45 E% for carbohydrate (Table 11).There were no significant differences between boys and girls with regard to energy intake (Table 10) or for protein, fat and carbohydrate intake (Table 11).

table 10. Reported energy intake and energy expenditure by sex in Yaoundé (paper IV)1.

All(N = 227)

Boys(N = 108)

Girls(N = 119)

P

BMRcal (kcal) 1383 ± 124 1413 ± 153 1356 ± 81 <0.001EIrep (kcal) 2324 ± 596 2354 ± 569 2297 ± 620 0.476EErep (kcal) 2327 ± 417 2512 ± 487 2162 ± 249 <0.001PAL (EErep/BMRcal) 1.68 ± 0.24 1.77 ± 0.27 1.59 ± 0.15 <0.001EIrep/EErep 1.02 ± 0.30 0.96 ± 0.27 1.07 ± 0.32 0.005EIrep/BMRcal 1.68 ± 0.44 1.67 ± 0.42 1.69 ± 0.47 0.768

Data are given as mean ± SD. 1Differences between boys and girls were analyzed using Student’s t-test.BMRcal: basal metabolic rate calculated, EIrep: energy intake reported, EErep: energy expenditure reported, PAL: physical activity level.

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30

table 11. Macronutrients intake by sex in Yaoundé (paper IV)1,2.

All(N=227)

Boys(N=108)

Girls(N=119)

P

Protein (g) 58 ± 19 59 ± 19 57 ± 19 0.483(% of energy intake) E% 10 ± 2 10 ± 2 10 ± 2 0.795

(< 10E%) 55 57 54 0.683(>30E%) 0 0 0 -

Fat (g) 76 ± 23 76 ± 22 76 ± 24 0.988(E%) 30 ± 7 30 ± 6 31 ± 8 0.219

(< 25 E%) 26 27 25 0.778(>35 E%) 25 24 27 0.627

Carbohydrate (g) 324 ± 101 331 ± 97 317 ± 104 0.265(% of energy intake) E% 60 ± 7 60 ± 6 59 ± 8 0.247

(<45 E%) 7 4 10 0.061(>65 E%) 11 9 1 0.540

Data are given as mean ± SD and percentage (%). 1Differences between boys and girls were analyzed using Student’s t-test and Chi-square test.2Acceptable macronutrient ranges for protein 10-30 E%, fat 25-35 E%, carbohydrate 45-65 E%.

Vitamin B1 intake was significantly higher among boys than girls (Table 12). Boys and girls were below the RDA for all the medians intake of vitamins and minerals except for vitamins A, C and iron (Fe), but only girls were below the RDA for the median intake of iron (Table 12).

table 12. Micronutrients intake in Yaoundé by sex1,2 (paper IV).

Total(N = 227)

Boys(N = 108)

Girls(N = 119)

p

Vit A (ug) 879 {451-1299} 779{346-1233} 945{595-1333} 0.084Vit B1 (mg) 0.6{0.5-0.8} 0.7{0.5-0.9} 0.6{0.5-0.8} 0.012Vit B2 (mg) 0.4 {0.3 -0.6} 0.4 {0.3-0.6} 0.4 {0.3-0.7} 0.754Vit B3 (mg) 8.1{5.8-10.8} 8.9{6.0-10.8} 7.6{5.6-10.8} 0.251Vit B6 (mg) 0.4 {0.2-0.7} 0.4 {0.2-0.6} 0.4 {0.2-0.7} 0.777Folate (ug) 92 {52-161} 92 {54-162} 92 {48-157} 0.838Vit B12 (ug) 0.9 {0.3-1.8} 0.9 {0.2-1.7} 0.9 {0.4-1.9} 0.296Vit C (mg) 44 {13-86} 43 {13-103} 44 {16-84} 0.838Ca (mg) 353 {249-528} 342 {248-521} 360 {262-529} 0.538Fe (mg) 13 {10 -17} 13 {10-19} 14 {11-17} 0.985Zn (mg) 4.6{3.3-6.1} 4.6{3.4-6.2} 4.7{3.2-6.1} 0.930

Data are given as median with 25th-75th percentiles in brackets. 1Differences between boys and girls were analyzed using Mann-Whitney test.2 Recommended dietary intake for vit A, 600 ug; vit B1, 1.2 mg boys/1.1 mg girls; vit B2, 1.3 mg boys/1.0 mg girls; vit B3, 16 mg; vit B6, 1.3 mg boys/1.2 mg girls; folate, 400ug; vit B12, 2.4 ug; vit C, 40 mg; Ca, 1300 mg; Fe, 12 mg boys/22 mg girls; Zn, 9.7 mg boys/7.8 mg girls.

31

ResULTs

Figure 7. Proportion (%) of boys (N =108) and girls (N =119) reporting a dietary intake below es-timated average requirement (EAR), between EAR and recommended dietary allowance (RDA) and above RDA for vitamins and minerals in Yaoundé (paper IV)1.1Differences between boys and girls were analyzed using Chi-square test.

The proportion of boys below the EAR was significantly lower for vitamins B1, B3 and iron (Fe) (Figure 7). The proportion of the adolescents below the RDA for vitamin A was significantly higher in boys than girls.

table 13. Reported energy intake and energy expenditure of adolescents by socioeconomic status (low, middle, high) in Yaoundé (paper IV)1.


(N = 94)Middle

(N =105)High

(N = 28)P

BMRcal (kcal) 1385 ± 133 1381 ± 116 1380 ± 122 0.959EIrep (kcal) 2306 ± 424 2327 ± 589 2377 ± 622 0.857EErep (kcal) 2353 ± 424 2306 ± 368 2316 ± 551 0.733PAL (EErep/BMRcal) 1.69 ± 0.24 1.66 ± 0.21 1.66 ± 0.28 0.663EIrep/EErep 0.99 ± 0.28 1.02 ± 0.28 1.09 ± 0.42 0.329EIrep/ BMRcal 1.66 ± 0.43 1.69 ± 0.45 1.74 ± 0.50 0.646

Data are given as mean ± SD. 1Differences between boys and girls were analyzed using univariate ANOVA. BMRcal: basal metabolic rate calculated, EIrep: energy intake reported, EErep: energy expenditure reported, PAL: physical activity level.

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32

There was no difference in energy intake between the adolescents with high, middle and low SES (Table 13). The adolescents with high SES had significantly higher fat intake and percentage of energy intake from fat than those with low SES (Table 14). In contrast, the adolescent with low SES had significantly higher percentage of energy intake from carbohydrate than those with high SES (Table 14).

table 14. Macronutrients intake by socioeconomic status (low, middle, high) in Yaoundé (Paper IV) 1,2.

Socioeconomic status Low

(N = 94)Middle

(N =105)High

(N = 28)P

Protein (g) 56 ± 19 59 ±19 59 ± 18 0.533(% of energy intake) E% 10 ± 2 10 ± 2 10 ± 1 0.507

(<10 E%)(>30 E%)

580

520

540

0.6760

Fat (g) 72 ± 22 77 ± 24 85 ± 23 0.019(E%) 29 ± 7 31 ± 7 33 ± 7 0.029

(<25 E%) 32 24 11 0.074(>35 E%) 19 28 39 0.081

Carbohydrate (g) 325 ± 103 323 ± 102 321 ± 92 0.969(% of energy intake) E% 61 ± 8 59 ± 7 57 ± 7 0.044

(<45 E%) 6 7 11 0.718(>65E%) 12 9 11 0.883

Data are given as mean ± SD and percentage (%).1Differences between low, middle and high SES were analyzed using univariate ANOVA and Chi-square test. 2Acceptable macronutrient ranges for protein 10-30 E%, fat 25-35 E%, carbohydrate 45-65 E%.

table 15. Micronutrients intake by socioeconomic status (low, middle and high) in Yaoundé (Paper IV)1,2.


(N=94)Middle

(N=105)High

(N=28)p

Vit A (ug) 862{410-1287} 879{539-1301} 878{439-1331} 0.886Vit B1 (mg) 0.6{0.5-0.8} 0.6{0.5-0.8} 0.7{0.5-10.0} 0.318Vit B2 (mg) 0.4 {0.5-0.5} 0.5 {0.3-0.7} 0.5 {0.4-0.7} <0.001Vit B3 (mg) 8.0{5.3-10.7} 7.6{5.8-10.3} 10.2{7.0-12.2} 0.118Vit B6 (mg) 0.3 {0.1-0.6} 0.4 {0.2-0.7} 0.5 {0.4-0.8} 0.020Folate (ug) 96 {48-138} 86 {47-167} 129 {60-222} 0.347Vit B12 (ug) 0.6 {0.1-1.1} 1.2 {0.5-1.9} 1.5 {0.7-2.6} <0.001Vit C (mg) 36 {3-87} 44 {18-83} 50{25-132} 0.122Ca (mg) 340 {226-539} 356 {253-504} 391 {283-615} 0.332Fe (mg) 13 {10-17} 14 {10-18} 14 {11-17} 0.896Zn (mg) 4.6{3.1-5.9} 4.8{3.4-6.5} 4.6{3.4-6.1} 0.601

Data are given as median with 25th-75th percentiles in brackets. 1Differences between low middle and high SES were analyzed using Kruskal-Wallis test.2 Recommended dietary intake for vit A, 600 ug; vit B1, 1.2 mg boys/1.1 mg girls; vit B2, 1.3 mg boys/1.0 mg girls; vit B3, 16 mg; vit B6, 1.3 mg boys/1.2 mg girls; folate, 400 ug; vit B12, 2.4 ug; vit C, 40 mg; Ca, 1300 mg; Fe, 12 mg boys/22 mg girls; Zn, 9.7 mg boys/7.8 mg girls.

33

ResULTs

The adolescents with high, middle and high SES were all below the RDA for all the medians intake of vitamins and minerals except for vitamins A and C. Vitamin C was below the RDA only for the adolescents with low SES (Table 15). The adolescents with high SES reported a significantly higher intake of vitamins B2, B6 and B12 than those with low SES.

Figure 8. Proportion (%) of adolescents with low (N= 94), middle (N= 105) and high (N= 28) socioeconomic status, reporting a dietary intake below estimated average requirement (EAR), between EAR and recommended dietary allowance (RDA) and above RDA for vitamins and minerals in Yaoundé (paper IV) 1.1Differences between low, middle and high SES were analyzed using Chi-square test.

The proportion of the adolescents below the recommendations for vitamin B12 was significantly lower among the adolescents with high SES compared to those with low SES (Figure 8).

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34

Validity of reported energy intakeBoys reported a significantly higher BMR, energy expenditure and PAL than girls and EIrep/EErep was significantly lower in boys than girls (Table 10).

Under-reporting and over-reporting were both common among the adolescents and varied according to sex and PAL groups (Table 16). Under-reporting was significantly higher and over-reporting significantly lower in boys than girls (p= 0.016) (Table 16). The proportion of under-reporters increased with increasing PAL among both boys and girls while the proportion of over-reporters decreased (p = 0.013 and p = 0.015 for boys and girls, respectively).

table 16. Validity of reported energy intake of adolescents in Yaoundé by physical activity level categories (PAL; low, moderate, high) (paper IV)1.

Boys (N = 102) Girls (N = 115)Low

(N = 41)Moderate(N = 41)

High(N = 20)

Low(N=76)

Moderate(N =31)

High(N=8)

Under-reporters 16 (39) 20 (49) 15 (75) 23 (30) 10 (32) 6 (75)Acceptable re-porters

10 (24) 10 (24) 4 (20) 14 (19) 9 (29) 2 (25)

Over-reporters 15 (37) 11 (27) 1 (5) 39 (51) 12 (39) 0 (0)

Data are given as number with proportion in parenthesis.1Differences between PAL groups or between boys and girls were analyzed using Chi-square test.

35

discussion The present study is the first with the aim to assess adolescents’ dietary intake, an-thropometry, physical activity by sex and SES, and to investigate their food percep-tion in Cameroon.

Overall, stunting, underweight and overweight were observed among the adoles-cents and varied according to sex and SES. The consumption frequency of different food groups was higher for urban adolescents, girls and the adolescents with high SES than rural adolescents, boys and the adolescents with low SES. Nutrients inadequacy was common among both boys and girls, and the adolescents with low SES had lower nutrient intake than those with high SES.

Adolescents’ food perceptions and habitsUrban adolescents with high SES were influenced by pleasure from eating food and adolescents from the urban low SES were influenced by “not enough money”; the rural adolescents succumbed in poverty. Lack of money or poverty has been influencing adolescents and adults’ food habits with low SES in Cameroon and Mali (46, 47). A possibility is that in the urban area food is always available especially in Yaoundé capital city, and the adolescents with high SES have enough money to buy food at school, whereas those with low SES do not always have enough money for food at school. However, the rural adolescents have no money or just a little to buy food at school. Another possibility is that the adolescents with high SES have good food availability at home, while those with low SES and those from the rural area do not because of lack of money. In fact, poverty is rated three times higher in urban than rural Cameroon with more inequality distribution of income among people in Yaoundé (4, 30). Adolescents from the urban area liked junk food such as cake, doughnuts, chips, candies, and soft drinks, which are sold cheap by vendors within and outside the school yard. On the other hand, there are few or no vendors within the school yard and food variety is minimal in the rural area as compared to the school in the urban area. Vendors selling junk food are increasing in many cities in Cameroon as well as in Africa (47, 48).

Both urban and rural adolescents said that food gives vitamins, probably because vitamin is a popular term in Cameroon to indicate healthy food by parents, teacher and health care personnel. Urban adolescents had better knowledge than rural ado-lescents about hypertension and diabetes, probably because these diseases are more prevalent in the urban area. Also the urban adolescents have better access to health information about hypertension and diabetes from media since they have televisions and radios at home. We found that urban girls with high SES whished to be normal weight while those with low SES preferred to be a little bit fat, and those from the rural area preferred to be even fatter. In Kenya to be corpulent was perceived as the cultural ideal of beauty, and in Arusha, Tanzania weight gain was perceived as a sign of wealth (49, 50). In fact, overweight is a sign of wealth, well-being, good health and beauty in Cameroon (8). In addition overweight is an indication that the person does

DIsCUssION

36

not have HIV-AIDS diseases. HIV-AIDS is considered a shameful disease, not to be disclosed and a HIV-AIDS patient is assumed to be quite slim.

Food groups consumption and meals pattern Urban adolescents with high SES had a higher consumption frequency of several food groups compared to those with low SES and those from the rural area. In sev-eral cities in Africa, people with high SES more often consume food from different food groups than those with low SES (11, 46-48, 51). An explanation could be that the adolescents with low SES and those living in the rural area do not always have access to food enough because of lack of money and many people living in the same household (11, 46). In addition, bread, meat/fish, milk products, and junk food are not always available in the rural area in Cameroon (46). Overall, girls had a more varied diet than boys because they reported higher consumption of food groups than the boys. An explanation could be that girls might eat while cooking since they are involved in food preparation together with their mothers.

In-between meals were more often consumed by the urban adolescents especially those with high SES. Lack of money could explain why the adolescents with low SES and the rural adolescents did not always eat in-between the meals (11, 46). In addi-tion, in-between meals were often composed of junk food, which seldom was available in the rural area. A higher proportion of girls than boys reported in-between meals consumption. In general in Cameroon women and girls eat more junk food than boys and men. Sometimes sweets food such as candies, biscuits, pastries and soft drinks are offered to women and girls as traditional gifts, whereas men and boys get other kinds of gifts but not food. It has been described in previous studies in other settings that girls are more attracted by sweet food than boys in other settings (50).

Physical activityRural adolescents in the present study reported doing heavy activities and walking to/from school and farm than urban adolescents. By contrast urban adolescents reported doing light activities, television viewing and using car transportation. An explanation is that the rural life is characterized by subsistence life with farming and many heavy domestic chores. While in the urban area life is more modern with few light domestic chores since there is water and electricity supplies at home as well as television and car. Moreover, food is supplied from the markets in the urban area. But there are inequalities in Yaoundé. Households with high SES have more equipment at home than those with low SES (11). Boys were more involved in heavy activities than girls, especially football playing, while girls were more involved in light activities such as cooking, doing homework as well as other household activities. This reflects a cultural gender difference regarding physical activity in Cameroon.

AnthropometryThe urban adolescents had a lower AMA value than rural adolescents probably because urban adolescents are less involved in doing household chores such as car-

37

DIsCUssION

rying water, farming and walking. Also the urban adolescents had a lower MUAC, waist circumference and WHR values because they were younger than the rural adolescents. Boys were more stunted and underweight than girls. Probably boys had less access to food and were more involved in heavy activity such as playing football than girls. A meta-analysis in sub-Saharan Africa including Cameroon found that boys under five years of age were more likely to be stunted than girls and this was more pronounced in the lowest SES group (52). A WHO study among adolescents in developing countries reported that boys were more underweight and stunted than girls in Cameroon and Mali (53). A study among boys in Nigeria showed that they were all underweight (54). By contrast, the present study showed that girls were more likely to be overweight than boys probably because they eat more food with less heavy activity than boys. Women were more overweight than men in a previous study among adults in Cameroon (9). Adolescents with low SES were more likely to be stunted than those with high SES probably because they did not always have access to enough food. In South-Africa, the children from the poorest households were more underweight than those from the richest households (55). In India, the prevalence of underweight was higher among the lower compared to the higher SES group, and in Mexico low SES was associated with stunting (56-58). In addition, infectious diseases mainly malaria, worms infestation, diarrhea and typhoid fever and their effects on appetite loss, low food intake, weight loss, altered metabolism are causing growth failure that manifest with underweight and stunting (10, 44). Moreover, income inequality, the poverty proportion (13%) as well as inequality of access to food in Yaoundé city could explain the prevalence of underweight and stunting observed in the present study (12). The relationship between underweight and stunting and low SES is well established in the literature and WHO recommends stunting as a measure of overall social deprivation (52, 55, 58, 59).

The overall prevalence of overweight (10%) among the adolescents in this study is almost comparable with the prevalence in some European countries (60). This is explained by consumption of junk food and food rich in fat and sugar, and by not enough physical activities among girls and the adolescents with high SES. Also overweight is perceived as a sign of wealth, good health and female beauty which may contribute to the prevalence of overweight. Modern life with less time for food preparation and more women working full time can explain the wide spread of junk food, ready to eat food and easily cooked food such as refined bread, pasta and cas-sava bread, fried plantain and potatoes.

Nutrient and energy intakeOverall, the proportion of the adolescents with inadequate nutrient intake was high in the present study. This is in accordance with many other dietary studies conducted in developing countries, which have reported a significant percentage of the ado-lescents having an intake of nutrients below the recommended standards (61-64). In the present study the reported energy and nutrients intake was generally lower

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38

among the adolescents with low SES compared to those with high SES. A likely reason for this inequality is that the adolescents with low SES do not always eat probably because of poverty. Poor access to food due to poverty has been described in several developing countries, and low SES has been associated with nutrient deficiencies among adolescents (22, 61-63, 65).

The lower fat intake among adolescents with low SES compared to those with high SES, confirms the results of a previous study in Cameroon where a low fat intake was found among households with low SES (46). Palm oil (containing mainly saturated fat), which is the main source of fat, may not always be affordable to the adolescents with low SES due to lack of money. Other fat rich food such as butter, yoghurt, milk and cheese are very seldom consumed since they are expensive and not always avail-able and considered as luxury snacks (46).

The percentage of energy intake from carbohydrates was high among the adoles-cents in the present study, especially among those with low SES. Carbohydrate was also shown to be high among adolescents with low SES in a Nigerian study (65). Carbohydrate rich foods are the main energy source and represent the main part of the household budget for food in Cameroon, especially among households with low SES (5, 46). Carbohydrate food such as cassava and maize flour, which are used for making porridge and gruel, are cheap and available all year round. These food items are easy to store since they are dry. Moreover, porridge is very popular because it goes well with different sauces and you get satisfied. Therefore, people usually eat porridge regularly and in large amounts. As described in paper II, some of the ado-lescents reported that they ate in order “to be filled up”.

Low intake of proteins, vitamins B1, B2, B6 and B12 is due to low intake of meat and fish since these food items are expensive. It was found that people with low SES were not accustomed to eating meat and fish due to the high cost. A national survey in Cameroon shows that the household “meat” budget of families with high SES was 119 time higher than for families with low SES (5, 46). In addition the fact that meat can not be stored due to lack of refrigerator can explain why it is not frequently consumed. Other food items rich in vitamins A, B1, B2 and B12 such as butter, milk products and eggs, also are seldom consumed since they are expensive, not always available and are not part of the food habits (46). Some animal foods are prohibited to women, and eggs are prohibited to children in some families especially those living in the rural areas and those with low educational level (5). Bush meat for example is prohibited because of the belief that “it might affect the woman reproductive health”. Eggs are prohibited because of the belief that “the child might become a thief”.

A higher proportion of boys had an intake of vitamin A below recommendations compared to girls in the present study. In South Africa, a study among black ado-lescents in urban area found that 78% had an intake below RDA for vitamin A (66). Vitamin A inadequacy is a problem in Cameroon and is explained by low intake of vitamin A rich food, inappropriate cooking methods and seasonal food availability (46). Palm oil and green leaves are the major sources of vitamin A in the country. The content of vitamin A as well as other vitamins decreases with commonly used cooking

39

DIsCUssION

methods such as bleaching palm oil by heating or preparing green leafy vegetables by boiling, squeezing and drying in the sun (44). Vitamin A rich foods such as carrots, papaya, water melon and mangoes are not always consumed because of the high cost, seasonal variation and the fact that they are not considered as food (46, 62, 64). Moreover, traditionally those fruits when available are more consumed by women and girls than men and boys since they are considered as “sweets for females”. This may explain the higher percentage of boys below RDA for vitamin A.

Overall lack of knowledge about nutrients in food was revealed in the qualitative study and may partly explain the nutrient inadequacy observed in our study. Prob-ably the adolescents do not have appropriate education in school about nutrients in food or food related diseases. Some commonly used food processing methods such as milling, smoking, storing, washing, and frying can alter the amount of vitamins and minerals in food (5, 44). Moreover it seems like people are not aware about the loss of vitamins B1 and B3 during the peeling, fermentation and drying of cassava. The amount of vitamins is decreased in maize during the drying and sifting process. Furthermore, people generally consume cooked leafy vegetables, pulse and nuts which may have low vitamins content because of leaching from the food into cooking water. Raw vegetables and fresh fruits rich vitamins are not often consumed because of cultural beliefs such as raw food “causing dysentery” and mangoes causing malaria (5).

Low iron intake has been related to iron deficiency among women and children in Cameroon (5). In the present study, boys and girls had similar iron intake, but the proportion below the EAR was ten times higher for girls as compared to boys because the requirements for girls are physiologically much higher compared to boys. Low iron intake among girls can lead to reproductive health problems. There is probably a lack of awareness that girls need to eat more iron rich food than boys because of menstruation. Moreover, iron rich food such as meat and fish is expensive and when available in some families only for the father to be eaten.

Diseases such as malaria, respiratory infections, tuberculosis, worms’ infestation (Ascaris 42% and Trichuris 53%) and diarrheal diseases may affect both the appe-tite and consequently the energy and nutrient intake but also the bioavailability of some nutrients and may cause malabsorption. This may contribute to an inadequate nutrient status, and lead to several vitamins and minerals deficiencies (4, 16, 22). However, we have not expanded our investigation to biochemistry measurements about nutritional status in the present study.

Validity of reported energy intakeThe high proportion of inadequate intake in the present study may be caused by either a true low intake or by underreporting of food intake, or a combination of the two. Under- and over-reporting were both common to a high extent in the present study. Mis-reporting of energy intake is a common problem in most dietary surveys (39, 64, 67, 68). However, the proportion of under-reporters was higher in our study compared to a Swedish study among adolescents (19% of under-reporting vs. 41% in our study) and lower than the proportion in a Canadian study among adolescents

DIsCUssION

40

(50%) (67, 68). The high proportion of over-reporters may be due to a desire to dem-onstrate affluence. In paper II, eating food was described as a sign of wealth and the more food you ate the better-off you were.

Boys were more often classified as under-reporters than girls because they may not be as aware about the food eaten, amounts and recipes used as the girls, who were more often involved in food preparation at home than the boys. Another possible explanation is that food cooking is considered a feminine subject and done only by girls in school, thus leading to them being more knowledgeable about food than the boys. It may also be that boys eat less food than they require due to gender differences in physical activity. The results showed that the boys were learners than the girls and were more involved in heavy activities confirmed by their higher EErep, PAL and football playing frequency, whereas girls were involved in doing household activities.

Health consequences Stunting, underweight, low protein, vitamin and mineral intake as found in the present study is likely to result in irreversible adolescent health consequences such as impaired intellectual development and bad school performance (visible through repeated year at school). Unless controlled, underweight and stunting among these adolescents might result in a reduction of adult size, which may in turn be associ-ated with reduced work capacity, altered cognitive functions, deficiency in muscular strength, and for women adverse reproductive health such as low birth weigh and abortion (17, 22, 24, 43, 53).

On the other hand, high fat and energy intake in relation to energy expenditure may lead to obesity, hypertension, stroke, type II diabetes and some cancers that are already prevalent in the country (7-9, 69). This shows that Cameroon is experiencing nutrition transition characterized by changes in dietary intake from traditional food to food high in fat and energy and low in vitamins and minerals as well as sedentary lifestyle. These diseases mentioned above are the major public health in western countries (70).

Limitations and strengthsThere are some problems in the present study which make the interpretation of our results complicated. However, the problems encountered are common in most surveys about food and nutrition and were dealt with in a suitable manner.

Firstly, information about food frequency, food ingredients and recipes were dif-ficult to obtain. Inaccurate information about food ingredients and recipes was also described among adults by other studies conducted in Cameroon and Mali (6, 64). To minimize this error, information about food ingredients and recipes were obtained from girls, vendors and restaurants. In addition, a picture booklet with 64 pictures containing pictures and weight of most commonly consumed foods was developed and used to help the adolescents for answering the questionnaire (Appendix). This is a unique tool in that area of nutrition. Also, food price, real food portions as well as household measures were used.

41

DIsCUssION

Secondly, nutrient content information of four main staple foods was incomplete in the available data bases. Laboratory nutrient analyses were therefore performed by an accredited laboratory. Thirdly, lack of specific values for nutrient requirements for the Cameroonian adolescents might have affected the proportion of the adolescents with low nutrient intake. To minimize this error, the WHO nutrients requirements value for developing countries was used as RDA. In addition, stratification by sex and SES could be a limitation due to small sub-sample and a possible reason for few significant differences between boys and girls and between SES groups. We conclude that the results of the present study could be applicable to similar set-tings in Cameroon and in Africa overall.

43

concLusions And recommendAtionsThe present study shows that low protein, low fat, low vitamin and mineral intake, and high fat and carbohydrate intake were common among the adolescents.Rural adolescents had a lower consumption frequency of most food groups and less often ate lunch and in-between meals than urban adolescents. However, the rural adolescents had more muscle than the urban adolescents. In the urban area, adoles-In the urban area, adoles-cents with high SES had a higher consumption frequency of different food groups and nutrient intake, and were less stunted than those with low SES.

Moreover, underweight, stunting, and overweight were common among the ado-lescents in Cameroon. Boys were more underweight and stunted than girls, while girls were more overweight and had higher prevalence of inadequate micronutrient intake than boys.

It is of great importance to prevent the rising prevalence of nutritional related dis-eases such as hypertension, cardiovascular diseases, obesity, type 2 diabetes mellitus, and nutritional deficiencies and infectious diseases. The present study gives valuable descriptive nutritional data that could be used when planning future intervention program aiming at improving the adolescents’ health.

Nutritional education at schoolProviding nutritional education at school is one way to improve dietary habits of ado-lescents. Nutritional education messages and practices should target the adolescent boys and girls from all SES groups. It should be part of the health care delivery at school and should be done using recommendations of healthy local and affordable food. The relationship between food groups and nutrients, food and health as well as food related diseases and deficiencies should be highlighted. Information about regular physical activities should also be included. Education materials to be used could be the food pyramid with healthy local food, drawing of foods, magazine, pic-tures, booklet and posters. Information about all food groups including fruits and milk product should be given. It should be emphasized that breakfast, lunch and din-ner should be consumed every day to maintain good health and high performance in school. Iron and folic acid supplementation should be given especially to girls.

Vendors should improve access to low cost healthy local foods (i.e. banana, pawpaw, pineapple, oranges, pears, carrots, maize combs, eggs, homemade yoghurt, enriched gruel with fruits and groundnuts, cassava bread enriched with oil and meat/fish) and decrease access to junk food in school.

Policy makers should control the media regarding the influence of western diet. Information about good hygiene and sanitation and provision of clean drinking water should also be included in future health programs.

CONCLUsIONs aND ReCOMMeNDaTIONs

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Figure 9. Measure of height.

45

AcknowLedGementsI would like to thank everybody who has contributed to my thesis.

Urban Janlert, my main supervisor whom I knew since the MASTER program at Umeå for his encouragement, support, help, and guidance during my study period. Thanks you to Urban, for his positive encouragements.

Christel Larsson, my co-supervisor whom I first met in 1998 during my exchange program as Erasmus student. I got inspired by her performance as nutritionist and PhD-holder. She motivated, trusted and supported me with all issues related to my studies. She was always honest and constructive with her comments. Thank you for her patience and positive comments that helped me to grow during this research process.

Agneta Hörnell, my co-supervisor, it was a great experience to work with her. She always gave me constructive comments and I felt that I have got a full education from her about doing research and writing articles. She “opened” my eyes about how to better express what I would like to say. She was also always patient and encouraged me all the time.

Lena Håglin, my co-author, thanks to Lena, for the educational support and help that she gave me from the MASTER to the PhD studies. She always trusted my capacity to do this thesis. Thanks for the regular dinners with her family at her house.

It was a pleasure to work with Lars Dahlgren, co-author, who helped me with quali-tative method with humour and assiduous.

I would like to thank Christophe Nouedoui, co-author, who helped, trusted and en-couraged me in this study. He was always supportive during my PhD studies.

It was a pleasure to work with Cécile Omoloko, co-author, who gave me the task of doing research in Cameroon in the area of Nutrition.

I am also very grateful to Hans Stenlund and Göran Lönnberg for helping me with the statistics.

I will also like to thank Eric Bergström, Eric Poortvliet, Fikru Tesfaye, Daniel Si-betcheu, Helena Palmgren, Liv Elin Torheim, Margareta Norberg, Félix Kisanga, Alisson Hernandez, Rosine Mayap, Jenet Agbor and all my friends from Burkina-Faso for the comments, advises and support you all gave me during this period.

Epidemiology and Global Health division was the “best” working place. It was an open international place with different nationalities, languages, gender and people with different backgrounds such as: administrative personnel, medical doctors, sociologists, social workers, nurses, physiotherapists, statisticians, epidemiologists and students, with experiences from different countries in Africa, Asia, America and Europe. It was educative to be there with all seminars, lectures, thesis presentations

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46

and “pumps” meetings. Thanks to Birgitta Åström, Ann Sörlin, Karin Johansson for helping me as well as my colleagues from Epidemiology. It was a positive experience, rich in learning, to work with all my colleagues from the Department of Epidemiol-ogy. It was a nice, supportive and friendly working environment.

I appreciate the efforts put by Albert Crenshaw in editing my thesis.

In Cameroon, I was very pleased to work with my colleague Mathe Medjo Ntolo, and all the University students who helped me with data collection.

I thank all the students in Yaoundé and Bandja-Manga who participated in this study.

Thank you to Anita, Uddo, Mona and Thomas Blomqvist for being my Swedish family, they comforted me, helped me, and did their best to make my stay nice in Umeå.

I am indebted to my parents Nzefa Tsachoua Pierre and Ngambou Nzefa Martine who gave financial and moral support in pursuing my studies in Umeå, Sweden. They have been supportive and confident about me. They encouraged me from the beginning, during my data collection in Cameroon, and writing process in Sweden. They were always present with telephone calls, good words and love. Special thanks to them, for they gave me the opportunity in my life for “freedom”.

Special thanks goes to all my brothers and sisters, Roger, Sylvain, Bertrand, Diane, Yves, Carine, Franck, Bertin as well as family Njélé for their support and help

I am very grateful to Olof Cronberg, for his love, support, cooperation and patience during this period. Thank you for reading and providing comments on my thesis.

I thank God, for He has always been with me.

Major funding for this study was from the Umeå Center for Global Health Research, Umeå University, Sweden, and the NESTLE Nutrition Paediatric Program scholar-ships of Vevey, Switzerland. Additional fundings were from: Västerbotten County, KEMPE foundation of Umeå University, Sweden, Engelbrekts Barnavårds Husmod-ersskola foundation of Stockholm, Sweden, Tage Erlanders foundation of Stockholm, Sweden and the Ministry of higher Education of Cameroon.

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Appendix Food pictures booklet

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Mogren I. Reproductive factors’ impact on the health of mother and offspring - An epidemiol ogical study. 1999. Umeå Univer sity Medical Dissertations New Series No 633.

Zelaya E. Adolescent pregnancies in Nicara gua. The importance of education. 1999. Umeå University Medical Dissertations New Series No 639.

Ellsberg MC. Candies in hell: Research and action on domestic violence against women in Nica ragua. 2000. Umeå University Medical Dissertations New Series No 670.

Johansson E. Emerging perspectives on tuber culosis and gender in Vietnam. 2000. Umeå Uni versity Medical Dissertations New Series No 675.

Nyström L. Assessment of population screen ing: the case of mammo graphy. 2000. Umeå Uni ver sity Medical Dissertations New Series No 678.

Berhane Y. Women’s health and reproductive outcome in rural Ethiopia. 2000. Umeå Uni versity Medical Dissertations New Series No 674.

Andersson T. Survival of mothers and their off spring in 19th century Sweden and contem po rary rural Ethiopia. 2000. Umeå University Medical Disserta tions New Series No 684.

Edlund C. Långtidssjukskrivna och deras me daktörer: en studie om sjukskrivning och reha bilitering. 2001. Umeå University Medical Dissertations New Series No 711.

Kwesigabo G. Trends in HIV infection in the Kagera region of Tanzania. 2001. Umeå Uni versity Medical Dissertations New Series No 710.

Öhman A. Profession on the move. Changing con ditions and gendered develop-ment in physio therapy. 2001. Umeå Uni versity Medi cal Dissertations New Series No 730.

Ivarsson A. On the multifactorial etiology of celiac disease. An epidemiological approach to the Swedish epidemic. 2001. Umeå Uni versity Medical Dissertations New Series No 739.

Grönblom-Lundström L. Rehabilitation in light of different theories of health. Outcome for patients with low-back complaints - a theoreti cal discussion. 2001. Umeå Uni ver sity Medi cal Dissertations New Series No 760.

Nurdiati D. Nutrition and reproductive health in Central Java, Indonesia. An epi-demiological approach. 2001. Umeå Uni versity Medical Dissertations New Series No 757.

Hyder SM Z. Anemia and iron deficiency in women. Impact of iron supplementation during pregnancy in rural Bangladesh. 2002. Umeå Uni versity Medi cal Dissertations New Series No 783.

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Utarini A. Evaluation of the user-provider inter face in malaria control programme: The case of Jepara district, Central Java province, Indonesia. 2002. Umeå Uni versity Medi cal Dissertations New Series No 805.

Ringbäck Weitoft G. Lone parenting, socioeco nomic conditions and severe ill-health. Longitu dinal register-based studies. 2003. Umeå Uni versity Medi cal Dis-sertations New Series No 828.

Chicovore J. Gender power dynamics in sexual and reproductive health. A qualita-tive study in Chiredzi District, Zimbabwe. 2004. Umeå Uni versity Medi cal Disserta-tions New Series No 876.

Sri Hartini Th N. Food habits, dietary intake and nutritional status durin economic crisis among pregnant women in Central Java Indonesia. 2004. Umeå Uni versity Medi cal Dissertations New Series No 885.

Emmelin M. Self-rated health in public health evaluation. 2004. Umeå Uni versity Medi cal Dissertations New Series No 884.

Lind T. Iron and zinc in infancy: Results from experimental trials in Sweden and Indonesia. 2004. Umeå Uni versity Medi cal Dissertations New Series No 887.

Hang HM. Epidemiology of unintentional injuries in rural Vietnam. 2004. Umeå Uni versity Medi cal Dissertations New Series No 914.

Hassler S. The health conditions in the Sami population of Sweden 1961-2002. 2005. Umeå University Medical Dissertations New Series No 962.

Valladares Cardoza E. Partner violence during pregnancy psychosocial factors and child outcomes in Nicaragua. 2005Umeå University Medical Dissertations New Series No 976.

Nguyen TX. The injury poverty trap in rural Vietnam: Causes, consequences and pos-sible solutions. 2005. Umeå University Medical Dissertations New Series No 990.

Oscarson N. Health Economic Evaluation Methods for Decision-Making in Preven-tive Dentistry. 2006. Umeå University Medical Dissertations New Series No 1004.

Månsdotter A. Health, Economics and Feminism. On judging fairness and reform. 2006. University Medical Dissertations New Series No 1013.

Ng N. Chronic disease risk factors in a transitional country. The case of rural Indo-nesia. 2006. Umeå University Medical Dissertations New Series No 1017.

Minh HV. Epidemiology of cardiovascular disease in rural Vietnam. 2006. Umeå University Medical Dissertations New Series No 1018.

Edin K. Perspectives on intimate partner violence, focusing on the period of preg-nancy. 2006. Umeå University Medical Dissertations New Series No 1041.

Dao Lan Huong. Mortality in transitional Vietnam. 2006. Umeå University Medical Dissertations New Series No 1036.

Nafziger A. A population perspective on obesity prevention: lessons learned from Swe-den and the U.S. 2006. Umeå University Medical Dissertations New Series No 1050.

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Kahn K. Dying to make a fresh start: mortality and health transition in a new South Africa. 2006. Umeå University Medical Dissertations New Series No 1056.Norberg M. Identifying risk of type 2 diabetes: epidemiologic perspectives from biomar-kers to lifestyle. 2007. Umeå University Medical Dissertations New Series No 1077.Hagberg L. Cost-effectiveness of the promotion of physical activity in health care. 2007. Umeå University Medical Dissertations New Series No 1085.Jerdén L. Health-promoting health services: Personal health documents and em-powerment.2007. Umeå University Medical Dissertations New Series No 1126.Tesfaye F. Epidemiology of cardiovascular disease risk factors in Ethiopia: The rural-urban gradient. 2008. Umeå University Medical Dissertations New Series No 1151.Fantahun M. Mortality and survival from childhood to old age in rural Ethiopia. 2008. Umeå University Medical Dissertations New Series No 1153.Fottrell E F. Dying to count: Mortality surveillance methods in resource-poor set-tings. 2008. Umeå University Medical Dissertations New Series No 1152.Dahlblom K. Home alone. Sibling caretakers in Léon, Nicaragua. 2008. Umeå University Medical Dissertations New Series No. 1210.Tollman S. Closing the gap: Applying health and socio-demographic surveillance to complex health transitions in South and sub-Saharan Africa. 2008. Umeå University Medical Dissertations New Series No. 1226.Sorensen J. Social marketing for injury prevention: Changing risk perceptions and safety-related behaviours among New York farmers. 2009. Umeå University Medical Dissertations New Series No. 1238.Emmelin A. Counted – and then? Trends in child mortality within an Ethiopian demographic surveillance site. 2009. Umeå University Medical Dissertations New Series No. 1256.Nilsson M. Promoting health in adolescents – preventing the use of tobacco. 2009. Umeå University Medical Dissertations New Series No. 1263.Collinson M A. Striving against adversity. The dynamics of migration, health and poverty in rural South Africa. 2009. Umeå University Medical Dissertations New Series No. 1251.Sahlén K-G. An ounce of prevention is worth a pound of cure. Preventive home visits among seniors. 2009. Umeå University Medical Dissertations New Series No. 1278.Kasenga F. Making it happen. Prevention of mother to child transmission of HIV in rural Malawi. 2009. Umeå University Medical Dissertations New Series No. 1284.Goicolea I. Adolescent pregnancies in the amazon basin of Ecuador – a rights and gender approach to girls’ sexual and reproductive health. 2009. Umeå University Medical Dissertations New Series No. 1294.Kidanto H L. Improving quality of perinatal care through clinical audit. A study from a tertiary hospital in Dar es Salaam, Tanzania. 2009. Umeå University Medical Dissertations New Series No. 1311.