Nutrition Chapter 8.doc

Nutrition Chapter 8: Dietary Supplements: Vitamins Minerals Herbs Amino Acids A dietary substance to supplement the diet Vitamins: Essential organic substances Produce deficiency symptoms when missing from diet. Yield no energy Fat-soluble and Water-Soluble vitamins Functions: Facilitate energy-yielding chemical reactions Function as co-enzymes Plant and animal foods provide vitamins Scientists have discovered ALL of the vitamins Most synthesized vitamins work equally well in the body. Storage of Vitamins in the Body: Fat Soluble: Not readily excreted (except Vitamin K) Water Soluble: Generally lost from the body (except B-6 and B-12) Excreted through urine VITAMINS SHOULD BE CONSUMED DAILY Occasional lapse is harmless. Vitamin Toxicity: Fat Soluble: Can accumulate in the body Water Soluble: Some can cause toxicity MOST LIKELY DUE TO SUPPLEMENTATION Preservation of Vitamins: Decreased vitamin content: Improper storage Excessive cooking Exposure to light, heat, air, water, and alkalinity Eat foods soon after harvest Freeze foods not consumed within a few days Blanching destroys enzymes Slows down vitamin degradation Fat Soluble Vitamins Overview: Dissolve in organic solvents Not readily excreted Can cause toxicity Absorbed along with fat Fat malabsorption May cause deficiency Transported with fat In lipoproteins Vitamin A: Narrow optimal intake range Preformed Retinoids Found in animal products Proformed Carotenoids Found in plant products Functions: Promote Vision Night blindness Promote Growth Prevent drying of the skin and eyes Promote immune function and resistance to bacterial infections Cardiovascular prevention Cancer prevention Acne medication Recommended Amounts 900 for men 700 for women Toxicity of Vitamin A: Large intake of vitamin A Over a long period Use of Accutane and Retin-A Signe and Symptoms Bone/muscle pain, loss of appetite, skin disorders, headache, dry skin, hair loss, increased liver size, vomiting Fetal malformation Possible permanent damage Vitamin D: Prohormone Derived from cholesterol Synthesized from sun exposure Insufficient sun exposure makes this a vitamin Activated by enzymes in liver and kidneys Deficiency can cause disease Functions: Regulates blood calcium Along with the parathyroid hormone Regulates calcium + phosphorus absorption Reduces kidney excretion of calcium Regulates calcium deposition in bones Influences normal cell development Linked to reduction of breast, colon, and prostate cancer Role in Bone Formation: Causes calcium + phosphorus to deposit in the bones Strengthens bones Rickets is the result of low vitamin D Breastfed infants with little sun exposure Osteomalacia; (soft bones) Rickets-like disease in adults Bones lose minerals and become porous Food Sources of Vitamin D: Fatty fish (salmon, herring) Fortified milk Some fortified cereal Intake: 5 a day for adults under 51 10-15 for older adults SUPPLEMENT IF A BREASTFED INFANT Toxicity: Vitamin D can be very toxic, especially in infancy and childhood Upper level is 50/day Results in: Over-absorption of calcium Calcium deposits in organs and blood vessels Growth retardation Vitamin E: Fat soluble antioxidant Resides mostly on cell membranes Protects double bonds in unsaturated fats Improves vitamin A absorption Deficiency Breakdown of cell membranes Hemolysis Nerve degeneration RDA is 15 mg/day Many adults are not meeting this goal. Toxicity: Upper level is 1,000 mg/day Toxic effects: Inhibit vitamin K metabolism and anticoagulants Possible hemorrhage Muscle weakness, headaches, nausea Vitamin K (?Koagulation?): Synthesized by bacteria in the colon and absorbed Role in coagulation process Role in calcium-binding potential Food Sources: Liver Green leafy vegetables Broccoli Peas Green Beans Resistant to cooking losses Limited vitamin K stored in the body Adeduate intake: 90 for women 120 for men Excess vitamin A and E Interferes with vitamin K May cause hemorrhage and fractures Newborns Routinely injected with vitamin K Breast milk is a poor sources Toxicity unlikely; ready excreted Overview of Water-Soluble Vitamins: Dissolve in water Generally readily excreted from body Subject to cooking losses Function as coenzymes Participate in energy metabolism 50-90% of B vitamins are absorbed Marginal deficiency more common Enrichment Act Thiamin B-1: Sensitive to alkalinity and heat Coenzyme form used in energy metabolism Deficiency: Beriberi RDA 1.1 mg/day for women 1.2 mg/day for men Most exceed RDA in diet Surplus is rapidly lost in urine; non-toxic Riboflavin B-2: Coenzyme forms participate in energy-yielding metabolic pathways Deficiency Cheilosis, inflammation of mouth and tongue, dermatitis, sensitivity to sun RDA 1.1 mg/day women 1.3 mg/day men Average intake is ABOVE RDA Non-toxic Food Sources of Riboflavin: Milk/milk products Enriched grains/cereals Eggs Liver Spinach Oysters Brewer?s yeast Niacin B-3: Coenzyme forms used in energy metabolism Deficiency Pellagra 3 D?s RDA 14 mg/day for women 16 mg/day for men Toxicity Upper Level is 35 mg/day Food Sources of Niacin: Enriched grains Beef Chicken/turkey Fish Heat stable; little cooking loss 60 mg tryptophan can be converted into 1 mg niacin Pantothenic Acid: Part of Coenzyme-A Essential for metabolism of carbohydrate, fat, and protein Deficiency Rare Usually in combination with other deficiencies Food Sources: Meat Milk Mushrooms Liver Peanuts Adequate Intake= 5mg/day Average intake meets AI Biotin: Free and bound form Co-enzyme Metabolism of carbohydrate and fat Helps breakdown certain amino acids Deficiency-rare Scaly, inflamed skin Changes in tongue, lips Decreased appetite, nausea, vomiting Food Sources: Cauliflower Egg Yolk Liver Peanuts Cheese Avidin inhibits absorption More than a dozen raw egg whites a day to cause this effect Biotin Needs: Adequate intake is 30/day for adults No upper level Relatively non toxic Vitamin B-6: Coenzyme forms Activate enzymes needed for metabolism of carbohydrate, fat, and protein Synthesize nonessential amino acids via transamination Synthesize neurotransmitters Synthesize hemoglobin and WBC Role in homocysteine metabolism RDA: 1.3 mg/day adults 1.7 mg/day men over 50 1.5 mg/day women over 50 Average intake is more than RDA Athletes may need more Alcohol increases vitamin B-6 destruction As a medicine? 50-100 mg/day therapy Questionable treatment of PMS May treat pregnancy hypertension Carpal Tunnel Syndrome Morning Sickness (100 mg/day) Toxicity potential ( > 200 mg/day can lead to irreversible nerve damage) Upper level is 100 mg/day Folate: Coenzyme DNA synthesis Homocysteine metabolism Neurotransmitter formation SYNTHETIC IS MORE POTENT THAN NATURAL Sensitive to: Heat Oxidation Ultraviolet light Folate Deficiency: Megaloblast cells Megaloblastic Anemia Neural tube defects Food Sources: Liver Fortified Breakfast Cereals Grains, Legumes Foliage Vegetables Orange Juice RDA: 400/day for adults 600/day for pregnant women Excess intake can mask vitamin B-12 deficiency Upper Level 1 mg Vitamin B-12: Synthesized by bacteria and fungi Coenzyme Role in folate metabolism Maintenance of the myelin sheaths RBC formation Deficiency Pernicious anemia Nerve degeneration and paralysis B-12 Absorption Requires a protein from salivary gland Requires stomach acid Requires the intrinsic factor Absorbed in the last part of the small intestine About 50% of B-12 is absorbed Therapy for Ineffective Absorption Many factors can disrupt this process (age) Monthly injections of vitamin B-12 Vitamin B-12 nasal gel Megadoses of B-12 Food Sources: Synthesized by bacteria, fungi, and algae (Stored primarily in the liver of animals) Animal Products Organ meat Seafood Eggs Hot Dogs Milk RDA for Vitamin B-12: 2.4/day for adults Average intake exceeds RDA B-12 stored in the liver Non Toxic Vitamin C: Synthesized by most animals Not by humans Decreased absorption with high intakes Excess excreted Diarrhea common Sensitive to Cooking/heat Iron, copper, oxygen Functions of Vitamin C Synthesis of collagen Iron absorption Immune functions Antioxidant? Deficiency of Vitamin C: Scurvy- Disease Deficient for 20-40 days Fatigue, pinpoint hemorrhages Bleeding gums Weakness Fractures Associated with poverty Food Sources: Citrus fruits Potatoes Green Pepper Cauliflower Broccoli Strawberries Romaine Lettuce Spinach RDA for Vitamin C: 90 mg/day for adult males 75 mg/day for adult females Daily Value is 60 mg +35 mg day for smokers Average intake 70-100 mg/day Upper level is 2g/day Choline: Essential nutrient, though not a vitamain All tissues contain choline Precursor for acetylcholine (neurotransmitter) Precursor for phospholipids Some role in homocysteine metabolism Food Sources of Choline: Widely distributed in foods Milk Liver Eggs Peanuts Lecithin added to food Deficiency rare Needs for Choline: 550 mg/day for males 425mg/day for females AI is 700-1000 mg/day High Doses Associated with fishy body odor, vomiting, salivation, sweating, hypotension, GI effects Upper Level is 3.5 grams/day Vitamin-like Compounds: Choline Carnitine Inositol Taurine Lipoic Acid Synthesized in the body at the expense of amino acids and other nutrients PAGE 1