THE NEXT EXAM IS FRIDAY APRIL 25. FIRST PAPER IS DUE MAY 12. MAY BE A QUIZ NEXT WEEK ON EXCHANGES.

Vitamin D Steroidal Prohormone  Calcitrol cholesterol backbone vitamin D prohormone  vitamin D 3  calcitrol sunlight requirement for reaction conversion in liver and kidneys to active form CALCITROL Deficiency can cause diseases

Vitamin D Synthesis

Absorption of Vitamin D ~80% of vitamin D consumed is incorporated into micelles Absorbed in the small intestine and transported via chylomicrons Transported through the lymphatic system Eventually to the liver and then kidneys

Metabolism and Storage of Vitamin D Vitamin D is converted to Calcitrol Stored in fat tissue and liver several week supply lost rapidly as a bile material Low blood calcium and phosphorus cause release of calcitrol.

Calcitrol improves calcium/phosphate absorption from the intestine and helps with bone formation Calcitriol creates a supersaturated Ca + Phos solution Causes Ca + Phos to deposit in the bones Strengthen bones

Deficiency of Vitamin D Rickets is the result of low vitamin D Osteomalacia (soft bone) is rickets in the adult

Who is at Risk for Deficiency? Elderly (staying indoors) People living in the northern climate People with fat malabsorption need sun exposure Vitamin D resistance Resistance to the action of vitamin D May be due to lack of calcitriol synthesis or inability to bind to nuclear receptor Requires large doses of calcitriol

The Adequate Intake (AI) for Vitamin D 5 ug/d (200 IU/day) for adults under age ug/day ( IU/day) for older Americans Light skinned individuals can produce enough vitamin D to meet the AI from casual sun exposure Infant are born with enough vitamin D to last ~9 months of age.

Food Sources of Vitamin D Fatty fish (salmon, herring) Fortified milk Some fortified cereal

Vitamin D as a Medicine Type II (age-related) osteoporosis Loss of bone mass Limited ability to absorb vitamin D or produce calcitriol ug vitamin D/ day plus calcium decrease bone fracture Risk for hypercalcemia Psoriasis Skin disorder Topical treatment

Toxicity Warning Vitamin D can be very toxic Regular intake of 5-10x the AI can be toxic Result from excess supplementation (not from sun exposure or milk consumption) Sign and symptoms: over absorption of calcium (hypercalcemia), increase calcium excretion Calcium deposits in kidneys, heart, and blood vessels Mental retardation in infants

Vitamin E Tocopherols and tocotrienols Amount absorbed is dependent on fat intake Incorporated into micelles Requires bile and fat digesting enzymes Transported via chylomicrons to the liver Transported via VLDL, LDL, HDL from the liver Found concentrated in areas where fat is found Excreted via bile and urine (much in feces due to limited absorption)

Antioxidant Agent Vitamin E is able to donate electron to oxidizing agent Protect the cell from attack by free radicals Peroxyl-radical scavenger Protects PUFAs within the cell membrane and plasma lipoproteins Prevents the alteration of cell’s DNA and risk for cancer development

Vitamin E, An Antioxidant Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Free Radicals Production is normal result of cell metabolism and immune function Destructive to cells; set off a chain reaction Lipid peroxidation More vitamin E is found in the lungs Smoking causes significant oxidative damage

The More The Better? Vitamin E is only one of many antioxidant It is likely that the combination of antioxidant is more effective Diversify your antioxidant intake with a balanced and varied diet Megadose of one antioxidant may interfere with the action of another

Other Functions of Vitamin E Protects the double bonds in saturated fat Role in iron metabolism Inhibits LDL oxidation Inhibits protein kinase C activity Enhance release of prostacyclin Maintenance of nervous tissue and immune function No specific role in metabolic reaction

Food Sources of Vitamin E Plant oils Wheat germ Asparagus Peanuts Margarine Nuts and seeds Actual amount is dependent on harvesting, processing, storage and cooking

RDA for Vitamin E 15 mg/day for women and men (=22 IU of natural source or 33 IU of synthetic form) Average intake meets RDA 1 mg d-  -tocopherol = 0.45 IU (synthetic source) 1 mg d-  -tocopherol = 0.67 IU (natural sources)

Deficiency of Vitamin E Hemolytic anemia Peripheral neuropathy Maldigestion of fat Insufficient bile production Rare

Who is at Risk for Deficiency? Premature infants People with fat malabsorption Cystic fibrosis, celiac disease, liver disease Low selenium intake

Toxicity of Vitamin E Supplements up to 800 IU is probably harmless Upper Level is 1,000 mg/day of any form of supplementary alpha-tocopherol Upper Level is 1500 IU (natural sources) or 1100 IU (synthetic forms) Inhibit vitamin K metabolism and anticoagulants

Vitamin K Phylloquinone (K 1 ) and menaquinones (K 2 ) 40%-80% of dietary vitamin K is absorbed Absorption requires bile and pancreatic enzymes Menaquinones are synthesized by the bacteria in the colon and are absorbed Role in the coagulation process Calcium-binding potential Formation of osteocalcin

Vitamin K and the Coagulation Process Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Drugs and Vitamin K Anticoagulant Lessens vitamin K reactivation Lessens blood clotting process Monitor vitamin K intake Antibiotics Destroy intestinal bacteria Inhibits vitamin K synthesis and absorption Potential for excessive bleeding

Food Sources of Vitamin K Liver Green leafy vegetables Broccoli Peas Green beans Resistant to cooking losses Limited vitamin K stored in the body

Adequate Intake for Vitamin K 90 ug/day for women 120 ug/day for men RDA met by most Excess vitamins A and E interferes with vitamin K Newborns are injected with vitamin K(breast milk is a poor source) Toxicity unlikely; readily excreted