Chapter 1. What You Eat and Why

Transcription

1 Chapter 1 What You Eat and Why

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3 What is nutrition?

4 Nutrition is the science of food, the nutrients and the substances therein, their action, interaction, and balance in relation to health and disease, and the process by which the organism ingests, absorbs, transport, utilizes, and excretes food substances The Council on Food and Nutrition of the American Medical Association

5 Nutrients Come from Food Provide energy Muscle contraction Cellular processes Digestion Provide building blocks Cellular structures

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7 Nutrients Come from Food Vital for growth and maintenance Infancy to adult Replenish replace cells in bone, skin, Essential

8 Essential Nutrient Omission leads to decline Regain normal function when restored to the diet Has specific biological function

9 Essential Nutrient Deficiencies Vitamin A night blindness Vitamin C scurvy Megadoses Vitamin A headache, joint pain Vitamin C benefit?

10 History of Nutrition Essentials of nutrition 100 years Essential indispensible Synthesized from precursors in diet conditional essentiality Nonessential dispensible Greece 500 B.C Practiced dietetic medicine (Hippocratic phys) No understanding of chemical nature of food Food contained single nutritional substance Aliment

11 History of Nutrition Great Britain Sydenham (1670) Iron filings in wine (anemia) Lind (1740) British physician Citrus fruit, Essential Limeys

12 History of Nutrition France (late 1700 s) LaPlace (guinea pigs, humans) Oxidation of carbon compounds (cells) Basic concepts of organic chemistry Food has a chemical nature Magendie (1816) First evidence of an essential nutrition Protein Dogs fed only CHO or fat, lost weight and died

13 History of Nutrition Great Britain Prout (1827) Protein, CHO, Fats Explanation of digestive process End of Hippocratic view of single aliment Ho. Next 20 years Chossat calcium Ca added to diet of wheat prevented mineral loss

14 History of Nutrition Liebig Sodium positively charged cation Other essential nutrients Beriberi Thiamine (B 1 ) Vitamin A 1915 Substance required for proper growth 6 minerals, 4 amino acids, A,B,C

15 Why study nutrition? Genetic traits determines quality of life LIFESTYLE Dietary factors Level of activity Overcome genetic traits

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17 Nutrition and Health Poor diet and sedentary lifestyle are risk factors for chronic diseases: Disease of the heart (29% of all deaths) Cancer (22%) Cerebrovascular disease (~7%) Diabetes (3%) Account for ~2/3 of all death

18 Nutrition and Health Maintain optimal health Poor nutrition in childhood Osteoporosis Affliction of Affluence Too much of a good thing We are living longer

19 The Six Classes of Nutrients Carbohydrates Lipids Proteins Vitamins Minerals Water

20 Nutrient Functional Categories Provide calories For growth, development, and maintenance Regulate body processes

21 Carbohydrates Composed of carbon, hydrogen, oxygen Major source of fuel Simple CHO Monosaccharide (glucose) Disaccharide-table sugar Sucrose fructose and glucose Complex forms Polysaccharides Dietary fiber-bonds bonds cannot be broken (undigested) Energy yielding (~4 kcal /gm)

22 Lipids Fats and oils Composed of carbon, hydrogen, fewer oxygen Triglycerides stored in body-adipose Saturated Fatty Acids animal fats Unsaturated Fatty Acids plant oils Essential Fatty Acids Vegetable oil - 4 tablespoons/week Energy yielding fats and oils (~9 kcal /gm)

23 Lipids Cholesterol structure of cell walls Obtained from diet Made by body Excess deposited on arterial walls Phospholipids Fat-related substances Essential part of cells Produced by body

24 Proteins Composed of carbon, hydrogen, oxygen, nitrogen Structural material (9) Essential amino acids (11) Nonessential amino acids Energy yielding (~4 kcal /gm) Not used for meeting daily caloric needs Excess protein intake-stored,

25 Vitamins Composed of various elements C, H, N, O, Ph, S Enable chemical reactions Fat soluble A,D,E,K Water soluble B family, C Yield no energy

26 Minerals Inorganic substances Function in cellular processes, nervous system, water balance, structural systems Not destroyed during cooking Trace minerals Major minerals Electrolytes Conduct electricity Yield no energy

27 Water Composed of hydrogen, oxygen Majority of our body weight Found in foods Yields no energy Recommended intake 9-13 cups/day Functions: Solvent, lubricant, medium for transport, chemical processes, and temperature regulator

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29 Transformation of Energy CHO PROTEIN FAT ALCOHOL (4 kcal/gm 4 kcal/gm 9 kcal/gm 7kcal/gm) ENERGY SOURCES Build new compounds Muscular movement Nerve transmission Ion balance

30 What is a Calorie? Measurement of energy the amount of heat it takes to raise the temperature of 1 gram of water by 1 degree Celsius 1,000 calories = 1 kcal = 1(food) Calorie

31 Sample Calculation of a Nutrition Label Per serving Carbohydrate: 15g x 4 kcal/g = 60 kcal PRO: 3g x 4 kcal/g = 12 kcal FAT: 1g x 9 kcal/g = 9 kcal TOTAL: 81 kcal, rounded down to 80 TOTAL: 81 kcal, rounded down to 80

32 Contribution to Total Kcal One day s s intake (1980 kcal) 290 gm of carbohydrate (x 4 kcal/gm) % of kcal as carbohydrate= (290 x 4)/1980 = 0.59 or 59% 60 gm of fat (x 9 kcal/gm) % of kcal as Fat= (60 x 9)/1980 = 0.27 or 27% 70 gm of protein (x 4 kcal/gm) % of kcal as PRO= (70 x 4)/1980 = 0.14 or 14%

33 The Typical American Diet 16% of kcal as proteins (10-35%) ~66% from animal sources 50% of kcal as carbohydrate (45-65%) ~50% from simple sugars 33% of kcal as fat (20-35%) ~60 % from animal fats Increased caloric intake kcals/day

34 Assessing Our Diets National Health and Nutrition Examination Survey (NHANES) [US Dept. of Health & Human Services] Collecting information about food consumption Survey based

35 Improving Our Diets Monitor energy intake Salt (sodium) in moderation Alcohol in moderation Fat in moderation Adequate fluids Eat 5-A-Day5 Use supplements wisely, if at all Mealtime is a social time

36 Healthy People Promote healthy lifestyle Reduce preventable deaths and diseases Reduce obesity in adults and children Increase intake of fruits, vegetables, and whole grain products Lower intake of fat, saturated fats, and sodium Increase intake of calcium and iron

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38 Belloc & Breslow,, 1972 Effectiveness of Lifestyle Changes 7 Lifestyle factors influenced length of life Participants followed for 9 years # of lifestyle factors followed was directly related to likelihood of dying

39 Belloc & Breslow,, Sleep 7 to 8 hours 2. No eating between meals 3. Eat breakfast regularly 4. Maintain proper weight 5. Regular exercise 6. Moderate or no use of alcohol 7. No smoking

40 Belloc & Breslow,, 1972 Age-adjusted death rate Health habits Men % dead in 9 yrs

41 Belloc & Breslow,, 1972 Age-adjusted death rate Women Health habits % dead in 9 yrs

42 Belloc Belloc & Breslow Breslow, 1972, Age Age

43 Hunger Why Am I So Hungry? Physical biological drive Appetite Psychological drive

44 Hypothalamus Satiety - regulated by the hypothalamus Feeding center eat Satiety center Stop eating

45 Hypothalamus Meal size Habit Composition High fiber Low fiber Hormones Increase hunger Endorphins, ghrelin, neuropeptide Y Increase satiety Leptin,, serotonin, cholecystokinin

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47 Scientific Research

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50 Evaluating claims