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Nutrition

Nutrition. Nutrition - Science of foods and nutrients Nutrient – a component of food that performs a physiological function All body functions depend on proper nutrition Food Guide Guides food choices to fulfill nutritional needs

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Nutrition

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  1. Nutrition • Nutrition - Science of foods and nutrients • Nutrient – a component of food that performs a physiological function • All body functions depend on proper nutrition • Food Guide • Guides food choices to fulfill nutritional needs • Guidelines change as nutritionists gain information… not a pyramid anymore!

  2. Nutrition - Guidelines • It’s just chemistry! • Balance energy taken in with energy used to maintain your weight • Eat a variety of foods • Our bodies require ALL the different types of nutrients for different things! • A balanced diet provides all the nutrients and vitamins you need! • Drink lots of water! • All those enzyme reactions (hydrolytic) need water.

  3. Nutrition - Guidelines • You still need fat! • A moderate total fat intake low in saturated fats and cholesterol • Protein is a must!!! • Vegetarians need to be especially careful! • Sources include poultry, fish, plants • Choose whole foods • Fresh fruits and veggies, whole grains, legumes, • Provides fiber and complex carbs • Avoid Processed foods • “white” breads and pastas (refined carbs) • Canned goods – often higher in sodium

  4. Nutrients: Carbohydrates • Primary energy source • Can be classified as simple carbohydrates or complex carbohydrates. • Simple carbohydrates are usually monosaccharides(single sugars) or disaccharides (two sugars linked together) • Glucose • Most important monosaccharide. • Most readily available energy source • Brain cells ONLY use glucose for energy! • Other cells can use fatty acids as well.

  5. Nutrients: Carbohydrates cont’d

  6. Nutrients: Carbohydrates cont’d Complex carbohydrates • Include oligosaccharides (chains of up to 10 sugars) and polysaccharides ( >10 sugars linked together) • Eg: starch, glycogen, and cellulose. • Get broken down to glucose • Contain fiber • Insoluble fiber - may protect against cancer • Soluble fiber - combines with bile acids and cholesterol

  7. Nutrients: Carbohydrates cont’d • Simple sugars (mono- and disaccharides) • Elevate blood sugar rapidly • Pancreas releases overload of insulin • Sugar taken up rapidly – hunger returns • Could lead to insulin resistance

  8. Reducing high glycemic index carbohydrates

  9. Nutrients: Proteins • Functions • Bodily growth and development • Regulate metabolism • Can be energy source (during starvation) • Used to make structural proteins in the body • Muscle, hair, skin, nails

  10. Nutrients: Proteins cont’d • Used for synthesis of other proteins, including: • Hemoglobin • Plasma proteins • Enzymes • Hormones • Synthesizing proteins… • Requires all 20 amino acids (building blocks for protein) • 8 must be supplied in diet - essential amino acids • Remaining 12 can be synthesized by the body

  11. Nutrients: Proteins cont’d. • “Complete” proteins • Contain all 20 amino acids • Eggs, meat, milk • “Incomplete” proteins • Generally from plants • Lack at least one essential amino acid • Vegetarians must combine plant protein sources • Complementary Proteins

  12. Complementary proteins • Table 14.5

  13. Nutrients: Proteins cont’d. • Amino acids are not stored in the body • Must take in daily supply • Too much protein can be harmful • Processing of amino acids produces urea • Urea excretion requires water • Can lead to dehydration • Can also cause calcium loss • Some protein-rich foods also are high in saturated fats (eg: red meat) • Can lead to cardiovascular disease

  14. Nutrients: Lipids • Used as energy storage (stores MUCH more energy than carbs) • Saturated fats • Solids at room temperature • Animal origin • Exceptions: palm oil, coconut oil • Associated with cardiovascular disease

  15. Nutrition: Lipids cont’d • Unsaturated fats (liquids at room temp.) • Oils contain mono- and polyunsaturated fats • Polyunsaturated oils contain essential fatty acids • Linoleic acid and alpha-linolenic acid • Omega-3 fatty acids • Especially protective against heart disease • Cold water fish, flax seed oil

  16. Nutrition: Lipids cont’d. Fats that cause disease: • Plaques- form in arteries • Contain cholesterol and saturated fats • Cholesterol • Carried in blood by low density lipoprotein (LDL) and high density lipoprotein (HDL) • LDL-”bad” cholesterol - transports from liver to cells • HDL- “good” cholesterol - transports to liver to make bile salts • Trans-fatty acids • May reduce ability to clear cholesterol • In commercially packaged foods • Linked to diabetes and heart disease

  17. Reducing certain lipids

  18. Nutrition: Vitamins • Coenzymes • organic molecules that are required by certain enzymes to carry out their reactions • Cofactors • inorganic substances that are required for, or increase the rate of, enzyme reactions • 13 vitamins • Fat soluble - A,D,E,K • Water soluble – B vitamins (8) and vitamin C

  19. Nutrition: Vitamins cont’d • Antioxidants • Vitamins C, E, and A • Defend against free radicals (eg: O2-, OH-) • Molecules responsible for aging and tissue damage • Cell metabolism creates free radicals • Damages DNA– causes a variety of harmful effects in cells. • (Lack of vitamin C causes scurvy)

  20. Free Radicals

  21. Scurvy

  22. Nutrition: Vitamins cont’d • Vitamin D • Converted in skin to active form by UV light • Further modified by kidneys and liver • Becomes “calcitrol” • Promotes calcium absorption from intestines • Deficiency causes rickets

  23. Fat-soluble vitamins • Table 14.7

  24. Nutrition: Minerals • Major minerals • Body contains more than 5 grams of these minerals • Found in components of cells • Also found in structural components (eg: teeth, bones) • Include magnesium, calcium, sodium, and potassium. • Trace minerals • Body contains less than 5 grams of these • Components of larger molecules • Iron - part of hemoglobin • Iodine - part of thyroxine (a thyroid hormone) • Zinc, copper, selenium - components of enzymes

  25. Minerals in the body • Fig. 14.17

  26. Nutrition: Minerals cont’d. Calcium • Deficiency causes osteoporosis • Bones become porous and fracture easily. • Calcium intake can slow bone loss • Requirements • Men and premenopausal women-1000 mg/day • Postmenopausal women-1300 mg/day • Vitamin D is essential in absorbing calcium!

  27. Nutrition: Minerals cont’d. Sodium • Requirement is 500 mg/day • Average intake in US is 4000-5000 mg/day • May be linked to hypertension • Only is naturally occurring in diet • added in processing • added as table salt

  28. Reducing dietary sodium • Table 14.10

  29. Nutrition: Eating Disorders Obesity • Body weight 20% above normal • 28% women and 10% men in US are obese • Hormonal, metabolic, and social factors • May be linked to lack of leptin- satiety hormone • Behavioral therapy is usual treatment

  30. Nutrition: Eating Disorders cont’d Bulimia Nervosa • Can coexist with obesity or anorexia • Binging and purging-damage from vomiting • Overly concerned about body shape and weight • Can damage kidneys and cause fatal arrhythmias • Psychotherapy and medication are treatments

  31. Recognizing Bulemia

  32. Nutrition: Eating Disorders cont’d Anorexia Nervosa • Morbid fear of gaining weight • Athletes at risk • Distorted self-image • All symptoms of starvation • Low blood pressure • Constant chilliness • Irregular heartbeat • Can result in death • Force-feeding and psychotherapy are critical

  33. Recognizing anorexia nervosa

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