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 B 12 deficiency, erosion of dental enamel

Table 1: Recommended Dietary Allowances (RDAs) for Vitamin C AgeMaleFemalePregnancyLactation 0–6 months40 mg* 7–12 months50 mg* 1–3 years15 mg 4–8 years25 mg 9–13 years45 mg 14–18 years75 mg65 mg80 mg115 mg 19+ years90 mg75 mg85 mg120 mg Smokers Individuals who smoke require 35 mg/day more vitamin C than nonsmokers.

Selected Food Sources of Vitamin C [12] Milligrams (mg) per servingPercent (%) DV* Red pepper, sweet, raw, ½ cup95158 Orange juice, ¾ cup93155 Orange, 1 medium70117 Grapefruit juice, ¾ cup70117 Kiwifruit, 1 medium64107 Green pepper, sweet, raw, ½ cup60100 Broccoli, cooked, ½ cup Food Strawberries, fresh, sliced, ½ cup4982 Brussels sprouts, cooked, ½ cup4880 Grapefruit, ½ medium3965 Broccoli, raw, ½ cup3965 Tomato juice, ¾ cup3355 Cantaloupe, ½ cup2948 Cabbage, cooked, ½ cup2847 Cauliflower, raw, ½ cup2643 Potato, baked, 1 medium1728 Tomato, raw, 1 medium1728 Spinach, cooked, ½ cup915 Green peas, frozen, cooked, ½ cup813