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Understanding Vitamins • Vitamins – Needed in small amounts (ug or mg) – Not an energy source – Vita(life)amine(containing N), are organic molecules needed as cofactors for enzymes – Essential for normal functioning, growth, and maintenance Understanding Vitamins • Fat-soluble vs. water-soluble – Fat-soluble: vitamins A, D, E, K • Absorbed with fat, into lymphatic system • Stored in larger quantities • Less vulnerable to cooking losses – Water-soluble: 8 B vitamins and vitamin C • Absorbed into bloodstream • Stored in small amounts • Vulnerable to cooking losses Understanding Vitamins • Food preparation affects vit content in food • Factors that determine amounts –Source (animal vs. plant) –Sunlight –Moisture –Growing conditions –Plant’s maturity at harvest –Packaging and storage Bioavailability – quantity & absorption Efficiency of dig. & transit time nutrient status other foods eaten food preparation source of nutrients Organic – can be destroyed by: - Temp - UV - Oxygen - Water Understanding Vitamins • Vitamins in foods – Enrichment and fortification • Enriched—replacing lost ingredients • Fortified—adding extra nutrients to foods • Some is required by law – Provitamins • Inactive Would your body have requirements that are greater than what you can receive in a balanced diet? Who thinks RDA is too low? Is benevolent industry CEOs thinking of your best interest? So is more better? Argument against supplements Toxicity Reduce bioavailability of other nutrients False sense of security Interfere with action of some medications Who may need supplements? People with nutritional deficiencies Low food intake diets Vegans Women of child bearing age Infants Certain medications People with certain diseases, infections or injuries People with genetic disorders Vitamin A: The Retinoids • Food sources – Preformed vitamin A: liver, milk, egg yolks – Beta-carotene: yellow/orange fruits and vegetables Vitamin A • Forms of vitamin A – Active forms (retinoids) • Retinol • Retinal • Retinoic acid – Carotenoids Vitamin A • Functions of vitamin A – Vision: night and day • Night and color vision • Becomes part of the retina Vitamin A • Functions of vitamin A – Cell production and differentiation – Skin – Immune function – Reproduction – Bones • Dietary recommendations – Retinol activity equivalent (RAE) Vitamin A • Vitamin A deficiency – The eyes • Xerophthalmia – The skin and other epithelial cells • Keratin – Immune function • Vulnerable to infection – Other effects • Growth retardation, bone deformities, defective teeth, and kidney stones Vitamin A Toxicity • Symptoms: loss of appetite, skin disorders, blurred or double vision, and liver damage • Teratogen – Causes birth defects – Discoloration of skin • Acne treatment – Retin-A and Accutane—use with caution The Carotenoids-Plant pigments • Convert vitamin A • Functions – Antioxident – Lower risk of certain cancer – Orange and yellow fruit and vegetables, dark green vegetables – Dietary fat increases absorption Photo © PhotoDisc Vitamin C, also known as ascorbic acid, is a water-soluble vitamin. Unlike most mammals and other animals, humans do not have the ability to make their own vitamin C. Therefore, we must obtain vitamin C through our diet. Vit C is required for synthesis of collagen, an important structural component of blood vessels, tendons, ligaments, and bone. - a highly effective antioxidant. - regenerate other antioxidants such as vit E Antioxidants block some of the damage caused by free radicals. They are made when you breaks down food or when exposed to tobacco smoke or radiation. The buildup of free radicals over time is maybe responsible for aging. Free radicals may play a role in cancer, heart disease, and conditions like arthritis A number of possible problems with very large doses of vitamin C have been suggested, including: atherosclerosis, kidney stones, excess iron absorption, vitamin B12 deficiency, erosion of dental enamel Table 1: Recommended Dietary Allowances (RDAs) for Vitamin C Age Male Female Pregnancy Lactation 0–6 months 40 mg* 40 mg* 7–12 months 50 mg* 50 mg* 1–3 years 15 mg 15 mg 4–8 years 25 mg 25 mg 9–13 years 45 mg 45 mg 14–18 years 75 mg 65 mg 80 mg 115 mg 19+ years 90 mg 75 mg 85 mg 120 mg Smokers Individuals who smoke require 35 mg/day more vitamin C than nonsmokers. Selected Food Sources of Vitamin C [12] Milligrams (mg) per serving Percent (%) DV* Red pepper, sweet, raw, ½ cup 95 158 Orange juice, ¾ cup Orange, 1 medium Grapefruit juice, ¾ cup Kiwifruit, 1 medium 93 70 70 64 155 117 117 107 Green pepper, sweet, raw, ½ cup 60 100 Food 51 85 Strawberries, fresh, sliced, ½ cup 49 82 Brussels sprouts, cooked, ½ cup 48 80 Grapefruit, ½ medium Broccoli, raw, ½ cup Tomato juice, ¾ cup Cantaloupe, ½ cup 39 39 33 29 65 65 55 48 Cabbage, cooked, ½ cup 28 47 Cauliflower, raw, ½ cup 26 43 Potato, baked, 1 medium 17 28 Tomato, raw, 1 medium 17 28 Spinach, cooked, ½ cup 9 15 Green peas, frozen, cooked, ½ cup 8 13 Broccoli, cooked, ½ cup