The Vitamins Fat Soluble Vitamins Water Soluble Vitamins Objectives Characteristics of Vitamins Vitamins are micronutrients Vitamins are essential. Very small amounts are needed by the body (>1 gm) Very small amounts are contained in foods. The roles they play in the body are very important. Most vitamins are obtained from the foods we eat. Some are made by bacteria in the intestine One is made in the skin There is no perfect food that contains all the vitamins in the right amount. Objectives Characteristics of Vitamins Vitamins are non-energy producing They do not contain kcalories. They are involved in extracting energy from the macronutrients. Some vitamins in foods are precursors. Vitamins are classified according to how soluble they are in fat or water. Fat Soluble Vitamins vs. Water Soluble Vitamins Variety is the Key Fat Soluble Vitamins Vitamin A, D, E, K Objectives Objectives After reading Chapter 6, completing a concept map and class discussion, you will be able to: Identify fat soluble vitamins Distinguish fat soluble vs water soluble Identify food sources for Vitamins A,D,E,K Identify toxicity levels for Vitamins A,D,E,K Describe one major role for Vitamins A,D,E,K Fat Soluble Vitamins: Characteristics Essential Organic Structure Non-energy Producing Micronutrients Stability Bioavailability Toxicity Vitamin Misconception “More is Better”? Toxicity Toxicity is rare but it is a possibility. Toxicity is very rarely associated with food. Toxicity results from overuse of supplements. Vitamin Concept Map FUNCTIONS Food Sources Vitamin Other Facts Vitamin A Functions SOURCES Vitamin A Other Facts Vitamin A Other names Preformed Vitamin A – retinyl esters Retinol, Retinal, Retinoic acid Sources: animal foods, fortified foods, pharmaceutical supplements Provitamin A - Precursors=carotenoids Beta-carotene and other carotenoids Sources: plant foods Vitamin A 2001 RDA Men: 900 g RAE/day Women: 700 g RAE/day RAE=Retinol Activity Equivalents 1 microgram of retinol 12 micrograms of beta-carotene 24 micrograms of other precursor carotenoid Upper level for adults: 3000 g/day Vitamin A Chief functions in the body Vision Maintenance of cornea, epithelial cells, mucous membranes, skin Bone and tooth growth Reproduction Immunity Antioxidant effect of beta-carotene Vitamin A in Vision Vitamin A Function in protein synthesis and cell differentiation Vitamin A Deficiency Night blindness Xerosis (corneal drying) Bitot’s spots Karatomalacia Xerophtalmia Hyperkaratosis Impaired immunity Vitamin A Deficiency Keratinization Vitamin A deficiency symptom Vitamin A Toxicity Toxicity from provitamin A impossible Conversion of carotenoids to retinal highly regulated by the body Homeostatic mechanisms control tightly Toxicity from preformed A inevitable Efficient absorption and hepatic storage of A Storage continues until pathologic condition develops; liver stores ~80% of body reserves Vitamin A Toxicity Large % of population in developed nations have intakes of preformed vitamin A higher than the RDA 75% of people may be routinely ingesting more than RDA Some studies suggest that as little as twice the RDA intake may contribute to subclinical Vitamin A toxicity Acute Toxicity Occurs when adults ingest >100x RDA of preformed Vitamin A for a period of hours or several days. Occurs when children ingest >20x RDA of preformed Vitamin A for same period. Less of a problem than chronic toxicity Acute Toxicity Acute toxicity symptoms Blurred vision Nausea, vomiting, vertigo Increase of pressure inside skull, mimicking brain tumor Headaches Chronic Toxicity Occurs when adults ingest >25,000 IU preformed Vitamin A for >6 years >100,000 IU preformed A for >6 months Wide individual variabilty Children particularly sensitive to daily intakes of 1500 IU/kg body weight. Elderly at significantly greater risk Chronic Toxicity Chronic toxicity symptoms Increased activity of osteoclasts causing reduced bone density Liver abnormalities Birth defects Vitamin A & Macular Degeneration Studies in the elderly suggest that the use of large doses of certain vitamins and minerals are beneficial in the prevention of macular degeneration Some evidence exists that improvement in existing damage may be seen Vitamin A & Macular Degeneration Vitamin/ Mineral A Amount % DV 14,320 IU 286 C 235 mg 371 E 200 IU 667 Zinc 348 mg 232 Copper 0.8 mg 40 WARNING Vitamin A & Macular Degeneration Vitamin A directs the process of borrowing and redepositing calcium in the bone Too much preformed Vitamin A (retinol) can promote fractures. Use Vitamin A in form of beta-carotene, a precurser form which does not increase fractures Vitamin A Sources Beta-carotene Dark leafy green vegetables, spinach, broccoli Deep orange veggies Carrots, pumpkin, squash, sweet potato Deep orange fruits Apricots, cantaloupe Vitamin A Sources Retinol Fortified milk, butter cheese, cream Fortified margarine Eggs Liver Copyright 2005 Wadsworth Group, a division of Thomson Learning Vitamin D Functions SOURCES Vitamin D Other Facts Vitamin D Other names Calciferol 1,25-dihyroxy vitamin D (calcitriol) Animal version: vitamin D3 or cholecalciferol Plant version: vitamin D2 or ergocalciferol Precursor is the body’s own cholesterol Vitamin D 1997 adequate intake (AI) 19-50 years: 5 g/day 51-70 years: 10 g/day more than 70 years: 15 g/day Upper level for adults: 50 g/day Vitamin D Chief functions in the body Mineralization of bones raises blood calcium and phosphorus by increasing absorption from digestive tract withdrawing calcium from bones stimulating retention by kidneys) Vitamin D Calcium and phosphorous absorption Without D only 10-15% dietary calcium absorbed With D absorption increased to 30-40% Without D about 60% phosphorous absorbed With D absorption increased to ~80% Vitamin D Recent research indicates Vitamin D has a role in the prevention of Heart disease Type-1 Diabetes Multiple Sclerosis Rheumatoid Arthritis Crohn’s Disease Certain Cancers Vitamin D Nonskeletal functions of Vitamin D Brain, prostate, breast, colon tissues and immune cells have Vitamin D receptors and respond to 1,25-dihydroxyvitamin D (the active form of D) 1,25-dihydroxyvitamin D controls more than 200 genes Potent immunomodulator Vitamin D Deficiency Rickets Inadequate calcification Misshapen, deformed Lax muscles with spasm Osteomalacia Loss of calcium Soft, deformed bones Pain, weakness Vitamin D Toxicity – Hypervitaminosis D Elevated blood calcium Calcification of soft tissues (blood vessels, kidneys, heart, lungs, tissues around joints) Thought to be the most frequently occurring vitamin toxicity but……….. Vitamin D The Sunshine Vitamin Approximately 90% of Vitamin D requirement obtained from sun UV light from sun hits skin, triggers synthesis Activated in liver and kidneys Vitamin D Sources Fortified Milk Margarine Butter Cereal Veal, Beef Egg yolk Fatty fish (salmon, sardines, herring) Vitamin E Functions SOURCES Vitamin E Other Facts Vitamin E Other name: alpha-tocopherol 2000 RDA Adults: 15 mg/day Upper level for adults: 1000 mg/day Easily destroyed by heat and oxygen Vitamin E Chief function in the body Antioxidant stabilization of cell membranes, regulation of oxidation reactions, protection of polyunsaturated fatty acids and vitamin A Vitamin E: Antioxidant Vitamin E Sources Polyunsaturated plant oils Margarine Salad dressing Leafy green vegetables Wheat germ Whole grains Egg yolks Nuts and seeds Vitamin K Functions SOURCES Vitamin K Other Facts Vitamin K Other names Phylloquinone Manaquinone Menadione Naphthoquinone 2001 AI Men: 120 g/day Women: 90 g/day Vitamin K Family of vitamins Naturally found in primarily two forms Identified by German scientists Required for normal blood clotting K1 and K2 K3 simpler form; synthetically created Named “K” for German word for “clot” No Tolerable Upper Limit Vitamin K Bacteria in intestines produce ~75% of Vitamin K absorbed by body daily Vitamin K not stored in body Vitamin K needs to be supplied daily Absorption dependent on healthy liver and gall bladder Vitamin K K1 produced by plants we eat K2 produced by bacteria in intestine; converted from K1 K2 more potent (15x); more active; and wider range of activities Better absorbed; longer biological activity Predominant form found in body tissues Used preferentially by all tissues but liver Vitamin K Chief functions in the body Synthesis of blood-clotting proteins and bone proteins that regulate blood calcium Vitamin K: Other Functions Synthesis of bone proteins that regulate blood calcium; prevent bone loss Integration of calcium into bones Prevent calcium deposition in blood vessels (vascular calcification) Maintain blood vessel elasticity Vitamin K and Medication Bisphosponates – osteoporosis drugs K improves utilization of these drugs Wafarin - anticoagulants As little as 1 mg/day can interfere with anticoagulant activity of drug Vitamin K Sources Bacterial synthesis in GI tract Leafy green vegetables Cruciferous vegetables Liver Milk Vitamin K Sources Vitamin K1 produced by plants and algae Broccoli, kale, chard; plant oils like canola and soybean Hydrogenated soybean oil has ineffective K Vitamin K2 produced by bacteria in gut Food Sources: fermented soybean (Natto); dairy products, egg yolk Objectives Antioxidants Objectives Antioxidants Objectives Objectives After reading Chapter 6, completing a concept map and class discussion, you will be able to: Identify fat soluble vitamins Distinguish fat soluble vs water soluble Identify food sources for Vitamins A,D,E,K Identify toxicity levels for Vitamins A,D,E,K Describe one major role for Vitamins A,D,E,K Objectives Fat Soluble Vitamins