HUEC 3115 Human Nutrition and Metabolism Fat Soluble Vitamin Charts Forms History Food Sources Absorption Vitamin K Phylloquininone Menaquinones Menadiones Named for the Danish word koagulation Dam and Doisy credited Leafy green vegetables and legumes Phylloquinone is the plant source also supplement form Light and heat can destroy Synthesized by intestinal bacteria 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 Transportat ion Functions 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 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 Vitamins A and E can negatively affect vitamin K Excess Vitamin A interferes with absorption Excess Vitamin E interferes with absorption and function Phylloquinone is almost completely metabolized Excretion in Menaquinones are metabolized to mendiol Excreted in the bile the bile some in the urine some in the urine AI 120 micrograms Males 90 micrograms Females Based on median intake from NHANES III No signs of deficiency occur at 80 micrograms 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 effects No UL based on large ingestions of phylloquinone and High amounts of methadione the synthetic product can cause liver damage hemolyetic anemia server jaundice etc Toxicity menaquinones Assessment 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 Interaction s with Other Nutrients Excretion Requireme nts Deficiency HUEC 3115 Human Nutrition and Metabolism Fat Soluble Vitamin Charts Forms Vitamin A 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 Food Sources Digestion Absorption Transportatio n Functions Vitamin A Functions Carotenoids McCollum 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 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 and proteolytic enzymes in the duodenum Carotenoids and free retinol incorporated into a micelle to cross brush border Inhibitition of absorption fiber especially pectin high levels of vitamin E and carotenoids inhibit or enhance other carotenoids 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 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 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 to protect the cell membrane Eye Health lutein and zeaxanthin Cataracts Heart disease carotenoid supplementation not Cell Proliferation growth and differentiation Carotenoids recommended inhibit cell proliferation HUEC 3115 Human Nutrition and Metabolism Fat Soluble Vitamin Charts Interactions with Other Nutrients Excretion Requirements Deficiency Toxicity Assessment IoM recommends not taking beta carotene supplements Excess Vit A interferes with vitamin K absorption Cancer megadoseas may impair 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 Catabolites of vit A are excreted in the urine 60 feces 40 Carotenoid excretion products released in the bile 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 Common in young children and developing countries Increased susceptibility to infections Leads to xeropthalmia dryness of eye Retards growth Keratinization of the skin 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 Blood levels of retinol are not reliable unless liver stores are deficient Vitamin E Forms Structures History Food Sources Tocopherols Tocotrienols Phenolic group on a chromanol chromane ring or head of the molecule and a phytyl isoprenoid side chain or tail Comes from the greek word tokos which means childbirth and phero which means to bring forth Good sources plant oils Can be oxidized by lengthy exposure to air and to light and Digestion Absorption Transportatio n heat Low fat diets can be low in vitamin E Vitmain E supplements and fortified foods use the forms all rac alpha tocopheryl succinate Tocopherols are found in free form in foods Tocotrineols and supplements are esterified Vitamin E is absorbed in the jejunum by non saturable passive diffusion Bile salts are required for emulsification 20 80 absorption Higher intake reduces absorption In mucosal cells tocopherols are put in chylomicrons for