HUEC 3115- Human Nutrition and Metabolism Fat Soluble Vitamin Charts Vitamin K Forms - Phylloquininone - Menaquinones - Menadiones History - Named for the Danish word “koagulation” - Dam and Doisy credited Food Sources - Leafy green vegetables and legumes - Phylloquinone is the plant source (also supplement form) - Light and heat can destroy - Synthesized by intestinal bacteria Absorption - Phylloquinone is absorbed in the jejunum as part of micelles- Menaquinones from bacteria are absorbed by passive diffusion in the ilieum and colon - Within intestinal cells vitamin K is incorporated into chylomicrons Transportation- Liver takes up chylomicron remnants and puts vit. K into VLDL- Absorbed menadiones are alkylated in the liver - Storage is highest in the liver- Body pool is 50 to 1000micrograms - Quick turnover of pool Functions - Activates blood clotting factors (II, VII, IX, X( by Y-carboxylating glutamic acid residues. - Production of Gla is necessary for binding of calcium - Two vitamin K dependent proteins in bone/cartilage: Osterocalcin and matrix Gla protein (MGP) Interactions with Other Nutrients - Vitamins A and E can negatively affect vitamin K - Excess Vitamin A interferes with absorption- Excess Vitamin E interferes with absorption and function Excretion - Phylloquinone is almost completely metabolized. Excretion in the bile, some in the urine- Menaquinones are metabolized to mendiol. Excreted in the bile, some in the urineRequirements - AI -120 micrograms (Males), 90 micrograms (Females)- Based on median intake from NHANES III- No signs of deficiency occur at >80 micrograms Deficiency - Rare in healthy adults - Newborns are most at risk. Recommended that all newborns get an intramuscular injection of phylloquinone to prevent HDNB - Antibiotics could be a problem resulting in deficiency - May lead to diminished bone mineral density - Prothrombin time is associated with adverse effectsToxicity - No UL, based on large ingestions of phylloquinone and menaquinones - High amounts of methadione, the synthetic product, can cause liver damage, hemolyetic anemia, server jaundice, etcAssessment- Plasma phylloquinones reflect 24hr intakes - Less than 0.5 micrograms/L considered deficient - Prothrombin times. *Vitamin A and Vitamin K were listed in the DRI book with trace minerals. Vitamins C, E, selenium, and carotenoids were listed together in a separate group.HUEC 3115- Human Nutrition and Metabolism Fat Soluble Vitamin Charts Vitamin AForms - Retinol - Retinal - Retinoic acid - Provitamin A carotenoids – compounds that are precursors to vitamin A Structures - Retinoids have a beta-inone ring and a polyunsaturated side chain, trans or cis double bonds are possible. History - McCollum Food Sources - VITAMIN A - Found in foods of animal origin, unless fortified plant foods - Good sources: Liver and whole milk (added to skim milk), fish- Can be oxidized by heat - Supplements (retinul acetate form)- CAROTENOIDS - Fruits and vegetables - Meat and fish Digestion- Vitamin A is often bound to other food components - Reinyl bound to fatty acid esters, freed by pancreatic and intestinal border hyrolyases and esterase- Retinyl bound to proteins freed by pepsin in the stomach andproteolytic enzymes in the duodenum Absorption - Carotenoids and free retinol incorporated into a micelle to cross brush border. - Inhibitition of absorption: fiber (especially pectin), high levelsof vitamin E, and carotenoids inhibit or enhance other carotenoids Transportation- Conversion of provitamin A carotenoids to retinoids in the liver, adipose, and lungs. - Carotenoids are stored in the liver and adipose tissue- Chylomicrons transport retinyl esters - Carotenoids transported by lipoproteins - Retinoic acid bound to cellular retinoic acid binding proteins (CRABPs) Functions Vitamin A - Vision- Cell differentiation. Retinoic acid affects gene expression - Growth. There are hetero and homo dimers of proteins that are transcription facts that act as receptors: RXR and RAR - Reproduction- Bone development - Immune function- Hematopoiesis Functions Carotenoids - Antioxidant function due to extended system of double bonds- Lycopene appears to be best for singlet oxygen and lipid peroxidation - Ability to react directly with radicals - Beta carotene and vitamin E appear to work synergistically toprotect the cell membrane. - Eye Health (lutein and zeaxanthin) - Cataracts - Heart disease (carotenoid supplementation not recommended)- Cell Proliferation, growth and differentiation (Carotenoids inhibit cell proliferation)HUEC 3115- Human Nutrition and Metabolism Fat Soluble Vitamin Charts - Cancer megadoseas may impair absorption - IoM recommends not taking beta-carotene supplements Interactions with Other Nutrients - Excess Vit. A interferes with vitamin K absorption - High beta carotene may reduce plasma vit E - Protein and zinc influence vit A status and transport - Iron is a cofactor for the 15,15’ mono-oxygenase conversion of beta carotene into retinal Excretion - Catabolites of vit. A are excreted in the urine (60%), feces (40%)- Carotenoid excretion products released in the bile. Requirements- RDA Men: 900 RAE (retinol activity equivalents) - RDA Women: 700 RAE (retinol activity equivalents)- 1 RAE = 1 microgram of retinol, 12 micrograms of beta carotene, and 24 micrograms of alpha-carotene or beta cryptoxanthin Deficiency - Common in young children and developing countries - Leads to xeropthalmia (dryness of eye) - Retards growth- Increased susceptibility to infections - Keratinization of the skin Toxicity - UL – 3,000 micrograms (10,000IU) - Hypervitaminosis A (chronic doses of 3 to 4 times the RDA) - Excess vitamin A or analogues are teratogenic (Accutane) - High dose vit, A increases serum levels - No UL for carotenoids, but supplements are not recommended Assessment- Blood levels of retinol are not reliable unless liver stores are deficient Vitamin EForms - Tocopherols- TocotrienolsStructures - Phenolic group on a chromanol/chromane ring or head of the molecule and a phytyl (isoprenoid) side chain or tail History - Comes from the greek word, “tokos” which means childbirth and “phero” which means to bring forth Food Sources - Good sources: plant oils - Can be oxidized by lengthy exposure to air, and to light, and heat - Low fat diets can be low in vitamin E- Vitmain E supplements and fortified foods use the forms all-rac alpha tocopheryl succinate Digestion- Tocopherols are