Bio 200: Human NutritionIntroduction

Lecture 101/05/2012

Objectives and Contents

• Objective: To give an overview of some of the concepts we will be looking at this quarter

• Contents:– Nutrition: What is it and it’s impact– Anatomy and Physiology– Essential and non-essential nutrients– Energy balance– The “SAD” diet: an assessment

What is Nutrition?

• The science and study of food on the health and disease of an organism– This includes how the organism ingests, digests,

absorbs transports and excretes food• Studies the relationship between food and

nutrients

Difference between food and nutrients

• Food – provides the energy and materials needed to build and maintain all cells and tissues within the body

• Nutrients– One specific biological function must be identified– Lack of nutrient results in decline in certain

biological function– Replacing the nutrient before permanent damage

occurs restores normal biological function

Why is nutrition important?

• In America, poor nutrition and related disorders can account for two-thirds of all deaths

• According to US government surveys, poor diet and lack of exercise add up to ~350,000 fatal cases of CV disease, cancer and diabetes

• Obesity is considered to be second leading cause of preventable death in America

Anatomy and Physiology

• The body is composed of trillions of cells• Cells of the same type are grouped together to

form tissues• One tissue or groups of tissues with similar

function are grouped together to form organs• Multiple organs involved in similar processes

form organ systems• All of the organ systems form the organism

There are 6 classes of nutrients

1. Carbohydrates2. Lipids3. Proteins4. Vitamins5. Minerals6. Water

Carbohydrates

• Composed primarily of carbon, oxygen and hydrogen.• Major energy source for the body; 4 kcal/gram• Hydrophilic• Exist as simple sugars and complex carbohydrates– Monosaccharides: single sugar molecules, i.e: glucose– Disaccharide: two monosaccharides joined together, i.e:

table sugar is fructose and glucose– Polysaccharide: long strands of monosaccharides strung

together (aka. complex carbohydrates), i.e: starch is made up of long strands of glucose molecules

Glucose: an example

Glucose as a Monosaccharide Glucose as a DisaccharideSucrose: (table sugar) consists of glucose and fructose

Glucose as a polysaccharide:Starch molecule consisting of multiple glucose molecules

Pictures courtesy of Wikipedia

Lipids: Fats and Oils

• Similar to carbohydrates, composed of mainly carbon, hydrogen and oxygen. Much less oxygen however

• Have high energy density; 9 kcal/gram• Hydrophobic• Triglyceride is primary form in the body and food• Exist in two main groups– Saturated fatty acids: all carbons are single bonds; solid

and room temp– Unsaturated fatty acids: contain one or more double bond;

liquid at room temp

Saturated vs. Unsaturated Fat

Courtesy of Wikipedia

Proteins

• Composed of carbon, oxygen, hydrogen, and nitrogen

• Main structural and functional material in the body

• Can also be used for energy however only done under very certain circumstances – 4kcal/gram

• Amino acids are bonded together to form proteins

Proteins

Courtesy of Proteopedia

Vitamins

• Varying complexity in chemical structure• Composed of carbon, hydrogen, nitrogen,

oxygen, phosphorus, sulfur, and other elements• Provide no caloric energy• Main function is to enable chemical reactions• 13 divided into two groups– Fat-soluble– Water-soluble

VitaminsVitamin AKA: (Not complete) Solubility

Recommended dietary allowances

Vitamin ARetinol, retinal, and four carotenoids including beta carotene Fat 900 µg

Vitamin B1 Thiamine Water 1.2 mgVitamin B2 Riboflavin Water 1.3 mgVitamin B3 Niacin, niacinamide Water 16.0 mgVitamin B5 Pantothenic acid Water 5.0 mgVitamin B6 Pyridoxine, pyridoxamine, pyridoxal Water 1.3–1.7 mgVitamin B7 Biotin Water 30.0 µgVitamin B9 Folic acid, folinic acid Water 400 µg

Vitamin B12Cyanocobalamin, hydroxycobalamin, methylcobalamin Water 2.4 µg

Vitamin C Ascorbic acid Water 90.0 mgVitamin D Cholecalciferol Fat 5.0 µg–10 µgVitamin E Tocopherols, tocotrienols Fat 15.0 mgVitamin K phylloquinone, menaquinones Fat 120 µg

Minerals

• Inorganic compounds• Broken down into two main categories– Major minerals; daily recommended intake >

100mg– Trace minerals; <100mg Daily recommended

intake• Minerals that conduct electricity when

dissolved in water are also termed elctrolytes

MineralsMineral RDA Major/Trace Purpose Dietary source

Potassium4700 mg Major A systemic electrolyte and is essential in coregulating ATP with sodium. Legumes, potato skin, tomatoes, and

bananas.

Chlorine 2300 mg Major Needed for production of hydrochloric acid in the stomach and in cellular pump functions. Table salt

Sodium 1500 mg Major A systemic electrolyte and is essential in coregulating ATP with potassium. Table salt

Calcium

1300 mg Major Needed for muscle, heart and digestive system health, builds bone, supports synthesis and function of blood cells. Dairy products, canned fish with

bones (salmon, sardines), green leafy vegetables, nuts and seeds.

Phosphorus

700 mg Major A component of bones, cells, in energy processing and many other functions. Red meat, dairy foods, fish, poultry,

bread, rice, oats. In biological contexts, usually seen as phosphate.

Magnesium 420 mg Major Required for processing ATP and for bones. Nuts, soy beans, and cocoa mass.

Zinc 11 mg Trace Required for several enzymes such as carboxypeptidase, liver alcohol dehydrogenase, and carbonic anhydrase.

Red meat including beef, lamb, and liver

Iron

18 mg Trace Required for many proteins and enzymes, notably hemoglobin to prevent anemia. Dietary sources include

Red meat, leafy green vegetables, fish (tuna, salmon), eggs, dried fruits, beans, whole grains, and enriched grains.

Manganese 2.3 mg Trace A cofactor in enzyme functions.

Copper 900 µg Trace Required component of many redox enzymes, including cytochrome c oxidase.

Iodine

150 µg TraceRequired not only for the synthesis of thyroid hormones, thyroxine and triiodothyronine, but also, probably as an antioxidant, for extrathyroidal organs as mammary and salivary glands and for gastric mucosa and immune system

Selenium 55 µg Trace A cofactor essential to activity of antioxidant enzymes like glutathione peroxidase.

Molybdenum45 µg Trace Used in the oxidases xanthine oxidase, aldehyde oxidase, and sulfite

oxidase[6]

Water

• Comprises ~60% of the human body• Acts as a solvent and lubricant• Transports waste• Average intake: ~3L for men and 2.2L for

women• Primary sources other than the tap: Fruit and

vegetables

Non-essential Nutrients: Phytochemicals

• Plant components that provide significant health benefits but not shown to be “essential”

• Usually found in whole foods• Include things like Carotenoids, Capsaicin, and

Flavanoids• Currently a hot topic in research – clinical trials are

ongoing for a number of phytochemicals that are thought to beneficial for cancer– The drug Taxol was a phytochemical isolated from the

Chinese Yew Tree.

Metabolism & Energy Balance

• Metabolism: The sum of all chemical reactions within the body– Catabolism-the breakdown of food and organic

compounds to provide energy; ie: glucose into ATP– Anabolism-Using energy to build structures and

components; ie: making proteins or cell membrane

Metabolism & Energy Balance

• Energy in food is measured in calories– The energy needed to raise the temperature of 1g

of water by 1oC.– Food calories are reported as Calories• Calories = 1000 calories = 1 kcal

• Average human needs ~ 2000 calories/day

• The problem is when “calories in” > metabolism

The Standard American Diet“SAD”

• AKA: Western pattern diet• Typically consists of: – High amounts of red meat– High in saturated fats– Refined grains– Refined sugars– Low fiber

• ~25% of Americans eat fast food every day• Average daily sugar intake = 22.2 tsp which is twice

what is recommended

VisualEconomics.com

Final Thoughts

• Hopefully by understanding the physiological requirements of the body you will be able to understand the nutritional requirements and food choices that you make everyday.