Chapter 18 Nutrition and Metabolism

1. Chapter 18Nutrition and Metabolism Nutrients – chemical substances supplied by the environment required for survival • Macronutrients • carbohydrates • proteins • fats • Micronutrients • vitamins • minerals • Essential Nutrients • human cells cannot synthesize • certain amino acids 18-2

2. Carbohydrates • Sources • sugars • starches • usually from plant sources • glycogen in meats • Excesses lead to • obesity • dental caries • nutritional deficits • Deficiencies lead to • metabolic acidosis • weight loss RDA is 125-175g 18-3

3. Utilization of Carbohydrates • oxidized for energy • production of certain molecules (ribose, deoxyribose) • stored in liver and muscles as glycogen • converted to fats and stored in adipose tissue 18-4

4. Lipids • Sources • meats • eggs • milk • lard • plant oils • Excesses lead to • obesity • increased serum cholesterol • increased risk of heart diseases • Deficiencies lead to • weight loss • skin lesions • hormonal imbalances RDA is 80-100g 18-6

5. Utilization of Lipids • oxidized for energy • production of triglycerides, phospholipids, lipoproteins, and cholesterol • stored in adipose tissue • glycerol may be used to synthesize glycerol 18-7

6. Proteins • Sources • meats • cheeses • nuts • legumes Excesses lead to obesity • Deficiencies lead to • extreme weight loss • muscle wasting • anemia • growth retardation RDA is 0.8g/kg body weight or 10% of diet 18-10

7. Utilization of Proteins • build cell structures • enzymes • hormones • transport of oxygen (hemoglobin) • regulation of water balance • control of pH • formation of antibodies • can be converted to carbohydrates or fats • may be broken down and oxidized for energy 18-11

8. Energy Values of Food Calorie – indicates amount of potential energy Carbohydrates 4.1 calories per gram Lipids 9.5 calories per gram Proteins 4.1 calories per gram • Basal metabolic rate • rate at which body expends energy at rest • primarily reflects energy needed to support activities of organs • varies with gender, body size, body temperature, and endocrine function • Energy needed • to maintain BMR • to support muscular activity • to maintain body temperature • for growth in children and pregnant women

9. Fat Soluble Vitamins • Vitamin A • necessary for • bone and teeth • development • visual pigments • Sources -- liver, fish, milk, leafy green vegetables, yellow and orange vegetables and fruits • Vitamin D • promotes absorption of calcium and phosphorus • necessary for bone and teeth development • Sources – skin, egg yolk, milk, fish liver oils

10. Fat-Soluble Vitamins • Vitamin K • necessary for • prothrombin synthesis • Sources – liver, soy oil, egg yolk, leafy green vegetables, tomatoes, cauliflower • Vitamin E • prevents oxidation of • vitamin A and some fatty • acids • may help stability of cell • membranes • Sources -- cereal seed oils, salad oils, margarine, shortening, fruits, nuts, vegetables 18-20

11. Water-Soluble Vitamins • Vitamin B1 (thiamine) • coenzyme for carbohydrate oxidation • Sources – meats, liver, leafy green vegetables, eggs, cereals, legumes • Vitamin B2 (riboflavin) • parts of enzymes and coenzymes (FAD) • Sources – milk, leafy green vegetables, meats • Pantothenic Acid • part of coenzyme A • Sources – meats, cereals, legumes, milk, vegetables • Niacin • parts of coenzymes (NAD) • Sources – liver, meats, peanuts, legumes 18-21

12. Water-Soluble Vitamins • Vitamin B12 • part of coenzyme needed for nucleic acid synthesis • plays role in myelin sheath formation • needed for RBC formation • Sources – meats, milk, liver, cheese, eggs • Vitamin B6 • part of coenzymes needed for synthesis of proteins • Sources – meats, cereals, peanuts, milk, bananas, avocados • Folic Acid • coenzyme required for amino acid and nucleic acid metabolism • needed for normal RBC production • Sources – cereals, legumes, milk, leafy green vegetables • Biotin • coenzyme required for metabolism of amino acids, fatty acids, and nucleic acids • Sources -- egg yolk, liver, legumes, nuts, mushrooms

13. Water-Soluble Vitamins • Vitamin C (ascorbic acid) • needed for collagen production and metabolism of some amino acids • promotes absorption of iron and synthesis of hormones from cholesterol • Sources -- citrus fruits, tomatoes, potatoes, leafy green vegetables 18-25

14. Minerals • Functions – part of structure of all cells, assist enzymes, contribute to osmotic pressure, help conduct nerve impulses, contract muscle, coagulate blood, maintain pH • Active form is ionized form of the mineral (Ca+2) • Trace Elements • iron • manganese • copper • iodine • cobalt • zinc • fluorine • selenium • chromium • Major Minerals • calcium • phosphorus • potassium • sulfur • sodium • chlorine • magnesium 18-26

15. Major Minerals • Calcium • mostly in bones and teeth • needed for bone structure • essential for nerve impulse conduction and muscle contraction • essential for blood coagulation • increases permeability of cell membranes • activates certain enzymes • Phosphorus • mostly in bones and teeth • needed for structure of bones and teeth • component in nearly all metabolic processes • constituent of ATP, nucleic acids, many proteins, enzymes, and some vitamins

17. Malnutrition • poor nutrition • undernutrition – deficiency of essential nutrients • overnutrition – excess of nutrient intake • primary malnutrition – malnutrition from diet alone • secondary malnutrition – diet is sufficient but nutrients cannot be absorbed 18-35

18. Starvation • person can survive 50-70 days without food • symptoms include low blood pressure, slow pulse, chills, dry skin, hair loss, and poor immunity • Marasmus – lack of all nutrients • Kwashiorkor – protein starvation • Anorexia nervosa – eating disorder; self-starvation • Bulimia – eating disorder; bingeing and purging 18-36