chapter 13 nutr

© 2009 Cengage - Wadsworth

Chapter 13

The Trace Minerals


The Trace Minerals--An Overview

• Trace minerals are needed in very small quantities in the human body. They perform many essential functions important to health.

• Toxic levels can easily be reached with the use of supplements.

• Humans can get the amounts of trace minerals needed by consuming a wide variety of foods.



• Food SourcesDepends on soil and water

compositionDepends on processingBioavailabilityWide variety of unprocessed foods



• DeficienciesSevere deficiencies of some minerals

are easy to recognize, while others can be difficult to diagnose.

Mild deficiencies are easily overlooked.

Deficiencies have wide-reaching effects.

Deficiencies affect all ages, but in children, they can affect growth.



• ToxicitiesDo not exceed Tolerable Upper Intake

Levels.FDA does not limit amounts in supplements.Do not exceed 100% Daily Values.

• InteractionsCommon and coordinated to meet body

needsCan lead to nutrient imbalances


Iron

• Iron is an essential nutrient found in the body as a part of hemoglobin and myoglobin.

• Iron is used for energy metabolism and enzyme activity.

• Special proteins assist with iron absorption, transport, and storage.

• Both iron deficiency and iron toxicity cause damage so balance is important.

• Heme iron is better absorbed but nonheme iron absorption can be enhanced.


Iron

• Iron Roles in the BodyFerrous iron is reduced and has a net

positive charge of two.Ferric iron is oxidized and has a net positive

charge of three.Cofactor in oxidation-reduction reactionsUtilization of energy in cell metabolismPart of the protein hemoglobin which carries

oxygen in the bloodPart of the protein myoglobin in the muscles

which makes oxygen available for muscle contractions


Iron

• Iron Absorption and MetabolismIron Absorption

• The protein ferritin stores iron in the mucosal cells lining the digestive tract.

• Transfers iron to mucosal transferrin.• Transfers iron to blood transferrin• Transports iron to the cells• Excreted and replaced as needed


Iron

• Iron Absorption and MetabolismHeme and Nonheme Iron

• Heme iron– Found in foods that are from the flesh of

animals (meat, poultry, and fish)– Represents only 10% of a days iron

consumption, but has an absorption rate of 25%

• Nonheme iron– Found in plant-derived and animal-derived

foods– Has an absorption rate of 17%


Iron

• Iron Absorption and MetabolismAbsorption-Enhancing Factors

– MFP factor enhances the absorption of nonheme iron.

– When nonheme iron is consumed with vitamin C at the same meal, absorption of iron increases.

– Citric acid and lactic acid from foods, HCl from the stomach, and sugars enhance nonheme iron absorption.


Iron

• Iron Absorption and MetabolismAbsorption-Inhibiting Factors

• Phytates and fibers from legumes, grains, and rice• Vegetable proteins in soybeans, legumes, and nuts• Calcium in milk• Tannic acid and other polyphenols in tea, coffee,

grains, oregano, and red wineDietary Factors Combined

• Difficult to assess iron absorption with meal consumption

• Most relevant factors are MFP factor and vitamin C in enhancing absorption and phytates in inhibiting absorption


Iron

• Iron Absorption and MetabolismIndividual Variation

• Dietary factors• Health status• Stage in life cycle• Iron status


Iron

• Iron Absorption and MetabolismIron Transport and Storage

• Surplus is stored in bone marrow, spleen, and liver

• Hemosiderin is a storage protein used when concentrations of iron are extremely high.

• Storing excess iron is a protective measure because iron can act as a free radical.


Iron

• Iron Absorption and MetabolismIron Recycling

• The liver and spleen dismantle red blood cells and package iron into transferrin.

• Transferrin carries iron in the blood.• Bone marrow incorporates iron into

hemoglobin and stores iron as ferritin.• Iron-containing hemoglobin carries

oxygen in the blood.• Iron is lost when bleeding occurs and

through the GI tract.


Iron

• Iron Absorption and MetabolismIron Balance

• The absorption, transport, storage, recycling, and loss of iron must be regulated in order to maintain iron balance.

• Hepcidin is a hormone that inhibits the absorption and transport of iron to keep blood levels within normal ranges.


Iron

• Iron deficiency is the most common nutrient deficiency. Iron-deficiency anemia can affect individuals

in many stages of life.Vulnerable Stages of Life

• Women in reproductive years due to menstruation

• Pregnant women due to the needs of the infant, increases in blood volume, and loss of blood during the birthing process

• Infants and young children due to rapid growth• Teenagers due to rapid growth in males and

menstruation in females


Iron

• Iron DeficiencyBlood Losses

• Can be from non-obvious sources such as a bleeding ulcer

• Malaria and parasites• Giving a pint of blood results in a loss of

about 2.5 mg iron.• Menstruation


Iron

• Iron DeficiencyAssessment of Iron Deficiency

•Stage 1 – Iron stores diminish; measured by serum ferritin

•Stage 2 – Transport iron decreases; measured by transferrin saturation

•Stage 3 – Hemoglobin production declines; erythrocyte protoporphyrin accumulates and hematocrit declines. Hemoglobin and hematocrit are late indicators of iron status.


Iron

• Iron DeficiencyIron Deficiency and Anemia

• Iron deficiency is when there is depletion of the body’s iron stores.

• Iron-deficiency anemia is the severe depletion of iron stores. Also called microcytic (small) hypochromic (pale) anemia.

• Symptoms include fatigue, weakness, headaches, apathy, pallor and poor resistance to cold temperatures.


Iron

• Iron Deficiency Iron Deficiency and Behavior

• Energy metabolism is impaired.• Neurotransmitter synthesis is reduced.• Physical work capacity and mental productivity are

reduced.• Symptoms of a deficiency may be confused with

behavioral issues. Iron Deficiency and Pica

• Generally found in women and children from low-income groups

• Eating ice, clay, paste, and other nonfood substances• Eating nonfood substances will not correct the

deficiency.


Iron

• Iron ToxicityIron Overload

• Hemochromatosis is generally a genetic disorder that enhances iron absorption and may be caused by a lack of hepcidin.

• Iron overload can also be caused by:– Repeated blood transfusions– Massive doses of supplemental iron– Rare metabolic disorders


Iron

• Iron OverloadHemosiderosis may develop from excessive

iron where there are large deposits of hemosiderin in the liver, heart, joints, and other tissues.

Symptoms of iron overload include apathy, lethargy, and fatigue.

Problems include liver tissue damage and infections.

Higher risk of diabetes, liver cancer, heart disease, and arthritis

More common in men then in women


Iron

• Iron Toxicity Iron and Heart Disease – may be a link to

high iron stores Iron and Cancer – may be a link with free

radical activity resulting in damage to DNA Iron Poisoning

• UL for adults: 45 mg/day• Accidental supplement poisoning in children• Symptoms include nausea, vomiting, diarrhea,

constipation, rapid heartbeat, weak pulse, dizziness, shock, and confusion


Iron

• Iron Recommendations and SourcesRecommended Iron Intakes (2001

RDA)• RDA Men: 8 mg/day for adults 19-50

years of age• RDA Women: 18 mg/day for adults 19-50

years of age• RDA Women: 8 mg/day for adults over 51

years of age• Vegetarians need 1.8 times as much iron

because of low bioavailability.


Iron

• Iron Recommendations and Sources Iron in Foods

• Red meats, fish, poultry, and shellfish• Eggs• Legumes• Grain products (whole-grain, enriched, and

fortified breads and cereals)• Dark greens and dried fruits

Iron-Enriched Foods• Often added to grain foods• Not absorbed as well


Iron

• Iron Recommendations and SourcesMaximizing Iron Absorption

• Bioavailability is high in meats, fish, and poultry.

• Bioavailability is intermediate in grains and legumes.

• Bioavailability is low in vegetables.• Combined effect of enhancing and

inhibiting factors


Iron

• Iron Contamination and SupplementationContamination Iron

• Iron cookware takes up iron salts.• Acidic foods and long cooking times increase

uptake of iron salts. Iron Supplements

• Best absorbable form is ferrous sulfate or an iron chelate

• Take on empty stomach and with liquids other than milk, tea, or coffee

• Vitamin C enhances food iron absorption, not supplement absorption.

• Side effect of constipation


Zinc

• Zinc is important in a multitude of chemical reactions in the body.

• The best sources of dietary zinc are protein-rich foods.

• Zinc from pancreatic secretions is also available for absorption.

• Phytates and fiber can bind zinc, therefore limiting absorption.

• A special binding protein monitors the absorption of zinc.

• Zinc deficiency symptoms include growth retardation and sexual immaturity.


Zinc

• Zinc Roles in the BodySupports the work of metalloenzymes

• Helps to make parts of DNA and RNA• Manufactures heme for hemoglobin• Assists in essential fatty acid metabolism• Releases vitamin A from liver stores• Metabolizes carbohydrates• Synthesizes proteins• Metabolizes alcohol• Disposes of damaging free radicals


Zinc

• Zinc Roles in the Body Involved in growth, development, and immune

function Affects platelets in blood clotting and wound healing Needed to produce the retinal form of vitamin A Affects thyroid hormone function Influences behavior and learning performance Taste perception Wound healing Sperm development Fetal development


Zinc

• Zinc Absorption and MetabolismZinc Absorption

• Rate of absorption depends on zinc status; when more is needed, more will be absorbed.

• Phytates and fiber bind zinc and reduce absorption.

• Metallothionein is a special protein that holds zinc in storage.


Zinc

• Zinc Absorption and MetabolismZinc Recycling

• Enteropancreatic circulation – travels from the pancreas to the intestines and back

• Losses occur in the feces, urine, shedding of skin, hair, sweat, menstrual fluids, and semen.


Zinc

• Zinc Absorption and MetabolismZinc Transport

• Transported by the protein albumin• Binds to transferrin • Excessive iron and copper can lead to a

zinc deficiency and excessive zinc can lead to an iron and copper deficiency.


Zinc

• Zinc DeficiencyNot widespreadOccurs in pregnant women, young children,

the elderly, and the poorSymptoms of deficiency

• Growth retardation• Delayed sexual maturation• Impaired immune function• Hair loss, eye and skin lesions• Altered taste, loss of appetite, and delayed wound

healing


Zinc

• Zinc ToxicityUL for Adults: 40 mg/daySymptoms

• Loss of appetite• Impaired immunity• Low HDL• Copper and iron deficiencies• Vomiting and diarrhea• Exhaustion • Headaches


Zinc

• Zinc Recommendations and SourcesRecommended intakes (2001 RDA)

• RDA Men: 11 mg/day• RDA Women: 8 mg/day

Zinc in foods• Shellfish, meats, poultry, milk, and cheese• Whole grains and legumes

• Zinc SupplementationDeveloping countries use zinc to reduce

incidence of disease and diarrhea.Zinc lozenges for the common cold are

controversial and inconclusive.


Iodine

• Iodide is an essential component of the thyroid hormone that helps to regulate metabolism.

• Iodine deficiency can cause simple goiter and cretinism.

• The iodization of salt has greatly reduced iodine deficiency in the United States and Canada.


Iodine

• Iodide Roles in the BodyComponent of two thyroid hormones

(T3 and T4)Regulates body temperature, growth,

development, metabolic rate, nerve and muscle function, reproduction, and blood cell production.


Iodine

• Iodine Deficiency Simple goiter is the enlargement of the thyroid gland

caused by iodine deficiency. Goiter is enlargement of the thyroid gland due to malfunction of the gland, iodine deficiency or overconsumption of goitrogens.

Goitrogen (antithyroid) overconsumption – naturally occurring in cabbage, spinach, radishes, rutabaga, soybeans, peanuts, peaches, and strawberries.

Cretinism is a congenital disease characterized by mental and physical retardation and commonly caused by maternal iodine deficiency during pregnancy.


Iodine

• Iodine ToxicityUL 1100 μg/daySymptoms include underactive

thyroid gland, elevated TSH, and goiter.

Supplement use, medications, and excessive iodine from foods


Iodine

• Iodine Recommendations and SourcesRecommendations (2001 RDA) – Adults: 150

μg/daySources

• Iodized salt• Seafood• Bread and dairy products• Plants grown in iodine-rich soils• Animals that feed on plants grown in iodine-rich

soils


Selenium

• Selenium is an antioxidant nutrient associated with protein foods.

• It may provide some protection against certain types of cancer.

• Selenium Roles in the BodyDefends against oxidationRegulates thyroid hormone


Selenium

• Selenium DeficiencyKeshan disease – a pre-disposition to

heart disease where a virus causes the cardiac tissue to become fibrous

Prevalent in regions of China because the soil is low in selenium


Selenium

• Selenium and CancerMay protect against certain forms of

cancerInconclusive evidence and more

research is neededFood sources are better than

supplements.


Selenium

• Selenium Recommendations and SourcesRecommendations (2000 RDA) –

Adults: 55 μg/daySources include seafood, meat, whole

grains, and vegetables (depends on soil content).


Selenium

• Selenium ToxicityUL for Adults: 400 μg/daySymptoms

• Loss and brittleness of hair and nails• Skin rash, fatigue, irritability, and nervous

system disorders• Garlic breath odor


Copper

• Copper is a component of several enzymes associated with oxygen or oxidation.

• Copper deficiency is rare. • There are some diseases associated

with excessive intakes. • Food sources of copper include

legumes, whole grains, and seafood.


Copper

• Copper Roles in the BodyAbsorption and use of iron in the

formation of hemoglobinPart of several enzymesSome copper-containing enzymes are

antioxidants.Required for many metabolic

reactions


Copper

• Copper Deficiency and ToxicityDeficiency is rare in the U.S.; however,

symptoms include anemia and bone abnormalities.

In Menkes disease, copper cannot be released into the circulation.

Toxicity• UL for Adults: 10,000 μg/day (10 mg/day)• In Wilson’s disease, copper builds up in the liver

and brain.• Excessive intake from supplements can cause

liver damage.


Copper

• Copper Recommendations and SourcesRecommendations (2001 RDA) –

Adults: 900 μg/daySources

• Seafood, nuts, seeds and legumes• Whole grains• In houses with copper plumbing, water

can be a source.


Manganese

• Manganese is a cofactor for several enzymes involved in bone formation and various metabolic processes.

• Deficiencies are rare and toxicities are associated with environmental contamination.

• Manganese is found in many foods.• Manganese Roles in the Body

Cofactor for several enzymesAssists in bone formationPyruvate conversion


Manganese

• Manganese Deficiency and ToxicityDeficiency symptoms are rare.Phytates, calcium and iron limit

absorption.Toxicity occurs with environmental

contamination.UL for Adults: 11 mg/dayToxicity symptoms include nervous

system disorders.


Manganese

• Manganese Recommendations and SourcesRecommendations (2001 AI)

• AI Men: 2.3 mg/day• AI Women: 1.8 mg/day

Sources• Nuts• Whole grains• Leafy vegetables• Tea


Fluoride

• Fluoride makes bones stronger and teeth more resistant to decay.

• The use of fluoridated water can reduce dental caries.

• Excess fluoride causes fluorosis—the pitting and discoloration of teeth.


Fluoride

• Fluoride Roles in the BodyFormation of teeth and bonesHelps to make teeth resistant to

decayFluorapatite is the stabilized form of

bone and tooth crystalsFluoride and Dental Caries

• Widespread health problem• Leads to nutritional problems due to

issues with chewing


Fluoride

• Fluoride and ToxicityTooth damage called fluorosis – irreversible

pitting and discoloration of the teethUL for Adults: 10 mg/dayPrevention of fluorosis

• Monitor fluoride content of local water supply.• Supervise toddlers during tooth brushing.• Watch quantity of toothpaste used (pea size) for

toddlers.• Use fluoride supplements only if prescribed by a

physician.


Fluoride

• Fluoride Recommendations and SourcesRecommendations (1997 AI)

• AI Men: 4 mg/day• AI Women: 3 mg/day

Sources• Fluoridated drinking water• Seafood and tea


Chromium

• Chromium is an essential nutrient that enhances insulin’s action.

• It is widely available in unrefined foods.• Chromium Roles in the Body

Enhances insulin actionLow chromium levels can result in elevated

blood sugar levels. Glucose tolerance factors (GTF) are small

organic compounds that enhance insulin’s action and some contain chromium.


Chromium

• Chromium Recommendations and SourcesRecommendations (2001 AI)

• AI Men: 35 μg/day• AI Women: 25 μg/day

Sources• Meat, especially liver• Whole grains• Brewer’s yeast

• Chromium SupplementsClaims about reducing body fat and

improving muscle strength remain controversial.


Molybdenum

• Molybdenum is a cofactor in several enzymes.

• It is needed in minuscule amounts. • It is available in legumes, grains, and

organ meats.• Molybdenum functions as a cofactor for

several enzymes.• No deficiency symptoms• No reported toxicity symptoms in humans


Molybdenum

• Recommendations (2001 RDA) Adults: 45 μg/dayUL Adults: 2 mg/day

• Food sources include legumes, grains, and organ meats.


Other Trace Minerals

• Much of the research on other trace minerals is from animal studies.

• Humans need very small amounts. • Determining exact needs, functions,

deficiencies, and toxicities is difficult. • Some key roles of these other trace

minerals have been identified.


Other Trace Minerals

• Nickel is a cofactor for certain enzymes.• Silicon is used in bone and collagen

formation.• Vanadium is for growth, development, and

normal reproduction.

• Cobalt is a key component of vitamin B12.

• Boron may be key in brain activities.• Arsenic is useful in some types of

leukemia.


Contaminant Minerals

• Contaminate minerals are also called heavy metals.

• These include mercury, lead, and cadmium.

• These minerals enter the food supply through soil, water, and air pollution.

• They disrupt body processes and impair nutrition status.



• Lead toxicity symptoms in childrenLearning disabilities in childrenLow IQBehavior problemsSlow growthDental caries Iron-deficiency anemiaSleep disturbances like night walking,

restlessness, and head bangingNervous system disorders and seizuresSlow reaction time and poor coordination Impaired hearing



• Lead toxicity symptoms in adultsHypertensionReproductive complicationsKidney failure


Phytochemicals and Functional Foods


Phytochemicals and Functional Foods

• Phytochemicals are nonnutrient compounds. • Only a few of the thousands of phytochemicals

have been researched. • There are many questions and few answers

about their role in human health. • Foods that provide health benefits beyond

those of nutrients are now called functional foods.

• Some have an identified role in disease prevention.


The Phytochemicals

• The phytochemicals give foods taste, aroma, color, and other characteristics.

• Defending against CancerPhytoestrogens mimic estrogen

• Found in soybeans, legumes, flaxseeds, whole grains, fruits and vegetables

• Antioxidant activity• Slow the growth of breast and prostrate cancer• Supplements may stimulate the growth of

cancers that depend upon estrogen.


The Phytochemicals

• Defending against CancerLycopene

• Powerful antioxidant• Inhibits the growth of cancer cells• Found in tomatoes and cooked tomato

products, apricots, guava, papaya, pink grapefruits, and watermelon

Five servings of fruits and vegetables are recommended every day.


The Phytochemicals

• Defending against Heart DiseaseFlavonoids in foods

• Powerful antioxidants• Protect against LDL cholesterol oxidation

and reduce blood platelet stickiness• Lowers risk of chronic diseases • Found in whole grains, legumes, soy,

vegetables, fruits, herbs, spices, teas, chocolate, nuts, olive oil, and red wines


The Phytochemicals

• Defending against Heart DiseaseCarotenoids in foods especially lutein and

lycopene• Lower risk of heart disease• Found in fruits and vegetables

Phytosterols• May protect against heart disease• Inhibit cholesterol absorption• Lower blood pressure• Act as antioxidants• Found in soybeans and other vegetables• Lignans, found in flax seed, are converted to

phytosterols by intestinal bacteria.


The Phytochemicals

• The Phytochemicals in PerspectiveDifficult to assess one food and its

benefits aloneActions of phytochemicals are

complementary and overlapping


Functional Foods

• Foods as PharmacyMargarine enhanced with a

phytosterol may lower cholesterol.May be more useful in prevention and

mild cases of disease.Drugs are used for severe cases of

disease.


Functional Foods

• Unanswered QuestionsResearch is lagging behind food

manufacturers.Consumer questions to ask

• Does it work?• How much does it contain?• Is it safe?• Is it healthy?


Functional Foods

• Future FoodsUse of gene researchCan we design foods to meet exact

health needs of each individual?Can farmers grow the “perfect”

foods?

chapter 13 nutr

Health & Medicine

iron iron absorption

iron iron roles

nonheme iron heme iron

transfers iron

iron deficiency

ferric iron

absorption ofnonheme

cengage wadsworth