{"id":4422598,"date":"2025-01-12T07:06:18","date_gmt":"2025-01-12T13:06:18","guid":{"rendered":"https:\/\/myendoconsult.com\/learn\/topics\/vitamins\/"},"modified":"2025-01-12T07:13:14","modified_gmt":"2025-01-12T13:13:14","slug":"vitamins","status":"publish","type":"oen_topic","link":"https:\/\/myendoconsult.com\/learn\/topics\/vitamins\/","title":{"rendered":"Vitamins"},"content":{"rendered":"\n<h2 class=\"wp-block-heading\">WATER-SOLUBLE VITAMINS<\/h2>\n\n\n\n<p><strong>General Absorption and Transport<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>All water-soluble vitamins (except vitamin B12) are absorbed mainly in the <strong>jejunum and ileum<\/strong>.<\/li>\n\n\n\n<li>Absorption mechanisms:\n<ul class=\"wp-block-list\">\n<li><strong>Passive diffusion<\/strong><\/li>\n\n\n\n<li><strong>Na+ (sodium)-coupled active transport<\/strong> pump<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li>Once in enterocytes, vitamins exit to portal circulation via a <strong>Na+-coupled ATP-dependent<\/strong> pump.<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN B1 (THIAMINE)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Biologic half-life<\/strong>: 10\u201320 days<\/li>\n\n\n\n<li><strong>Function<\/strong>: Key cofactor in amino acid and carbohydrate metabolism<\/li>\n\n\n\n<li><strong>Food sources<\/strong>: Yeast, brown rice, whole-grain cereals, legumes, pork<\/li>\n\n\n\n<li><strong>Storage<\/strong>: Limited tissue storage<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN B2 (RIBOFLAVIN)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Function<\/strong>: Flavin and component of flavin-adenine dinucleotide (FAD) \u2192 essential in mitochondrial redox reactions<\/li>\n\n\n\n<li><strong>Dietary sources<\/strong>: Meats, fish, milk, eggs, yeast, green veggies, enriched foods<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN B3 (NIACIN)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Two forms: <strong>Nicotinic acid<\/strong> and <strong>Nicotinamide<\/strong><\/li>\n\n\n\n<li><strong>Function<\/strong>: Form NAD and NADP (crucial for redox reactions in carb, fatty acid, and protein metabolism)<\/li>\n\n\n\n<li><strong>Food sources<\/strong>: Meat (especially liver), yeasts, cereals, legumes, seeds<\/li>\n\n\n\n<li><strong>Can be synthesized from tryptophan<\/strong> in humans<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN B5 (PANTOTHENIC ACID)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Key role in <strong>acetylation<\/strong> reactions (tricarboxylic acid cycle)<\/li>\n\n\n\n<li>Converted to <strong>coenzyme A<\/strong> after ATP-dependent phosphorylation<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Dietary sources<\/strong>: Egg yolk, liver, broccoli, milk, chicken, beef, potatoes, whole grains<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN B6 (PYRIDOXINE)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Absorption<\/strong>: Passive diffusion in jejunum and ileum<\/li>\n\n\n\n<li><strong>Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Critical in amino acid decarboxylation<\/li>\n\n\n\n<li>Gluconeogenesis<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Food sources<\/strong>: Meats, whole grains, vegetables, nuts<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">BIOTIN<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Cofactor in <strong>carboxylase<\/strong> enzymes<\/li>\n\n\n\n<li>Essential for carbohydrate &amp; <a href=\"https:\/\/myendoconsult.com\/learn\/topics\/lipid-lowering-therapy\/\"  data-wpil-monitor-id=\"296\">lipid metabolism<\/a> (acts as CO2 carrier)<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Food sources<\/strong>: Liver, egg yolk, soybean, yeast<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN C (ASCORBIC ACID)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Cofactor\/cosubstrate in reducing iron and copper (redox reactions)<\/li>\n\n\n\n<li>Provides electrons for molecular oxygen reduction<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Dietary sources<\/strong>: Citrus fruits, tomatoes, Brussels sprouts, potatoes, cauliflowers, broccoli, strawberries, cabbage, spinach<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN B12 (COBALAMIN)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Absorption<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Binds <strong>intrinsic factor (IF)<\/strong> in small intestine<\/li>\n\n\n\n<li>IF\u2013B12 complex binds <strong>cubilin<\/strong> in the <strong>ileum<\/strong> \u2192 requires energy<\/li>\n\n\n\n<li>Enters plasma bound to <strong>transcobalamins (TCs)<\/strong> (especially TCII)<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Function<\/strong>: Required for DNA synthesis, especially in rapidly dividing cells<\/li>\n\n\n\n<li><strong>Food sources<\/strong>: <strong>Meat<\/strong>, <strong>dairy products<\/strong> (only animal\/dairy sources)<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h2 class=\"wp-block-heading\">FAT-SOLUBLE VITAMINS<\/h2>\n\n\n\n<p><strong>General Absorption and Transport<\/strong><\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Released from proteins via gastric and pancreatic proteolysis<\/li>\n\n\n\n<li><strong>Bile salts<\/strong> solubilize vitamins in micelles for <strong>enterocyte uptake<\/strong><\/li>\n\n\n\n<li>Packaged into <strong>chylomicrons<\/strong> \u2192 enter intestinal lymphatics &amp; portal circulation \u2192 transported to liver<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN A<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Family of compounds: <strong>Retinols, \u03b2-carotenes, carotenoids<\/strong> (\u201cretinoic acids\u201d)<\/li>\n\n\n\n<li><strong>Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li><strong>Phototransduction<\/strong> (vision)<\/li>\n\n\n\n<li>Cellular differentiation, especially in eyes<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Dietary sources<\/strong>:\n<ul class=\"wp-block-list\">\n<li><strong>Retinols<\/strong>: Liver, egg yolk, butter<\/li>\n\n\n\n<li><strong>\u03b2-carotene<\/strong>: Green leafy vegetables<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN D (CALCIFEROL)<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Structure<\/strong>: Lipid-soluble with a four-ringed cholesterol backbone<\/li>\n\n\n\n<li><strong>Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li><strong>Calcium absorption<\/strong> &amp; bone metabolism<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Sources<\/strong>:\n<ul class=\"wp-block-list\">\n<li><strong>Sunlight<\/strong> (ultraviolet photoisomerization of provitamin D \u2192 vitamin D3\/cholecalciferol)<\/li>\n\n\n\n<li>Diet: Fortified milk, fatty fish, cod liver oil, eggs<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN E<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li><strong>Free radical scavenger<\/strong><\/li>\n\n\n\n<li>Protects polyunsaturated fatty acids from peroxidation<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Dietary sources<\/strong>: Oils, meat, eggs, leafy vegetables<\/li>\n<\/ul>\n\n\n\n<hr class=\"wp-block-separator has-alpha-channel-opacity\"\/>\n\n\n\n<h3 class=\"wp-block-heading\">VITAMIN K<\/h3>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Function<\/strong>:\n<ul class=\"wp-block-list\">\n<li>Cofactor for <strong>coagulation factors<\/strong> (VII, IX, X, prothrombin)<\/li>\n\n\n\n<li>Essential for \u03b3-carboxylation of certain proteins in coagulation<\/li>\n<\/ul>\n<\/li>\n\n\n\n<li><strong>Dietary vitamin K1 (phylloquinone)<\/strong>: Green leafy vegetables<\/li>\n\n\n\n<li><strong>Vitamin K2 (menaquinone)<\/strong>: Synthesized by <strong>gut microflora<\/strong><\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>WATER-SOLUBLE VITAMINS General Absorption and Transport VITAMIN B1 (THIAMINE) VITAMIN B2 (RIBOFLAVIN) VITAMIN B3 (NIACIN) VITAMIN B5 (PANTOTHENIC ACID) VITAMIN B6 (PYRIDOXINE) BIOTIN VITAMIN C (ASCORBIC ACID) VITAMIN B12 (COBALAMIN) FAT-SOLUBLE VITAMINS General Absorption and Transport VITAMIN A VITAMIN D (CALCIFEROL) VITAMIN E VITAMIN K<\/p>\n","protected":false},"featured_media":0,"template":"","oen_topic_chapter":[689],"class_list":["post-4422598","oen_topic","type-oen_topic","status-publish","hentry","oen_topic_chapter-obesity-medicine","post-wrapper","thrv_wrapper"],"_links":{"self":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422598","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic"}],"about":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/types\/oen_topic"}],"version-history":[{"count":3,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422598\/revisions"}],"predecessor-version":[{"id":4422602,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic\/4422598\/revisions\/4422602"}],"wp:attachment":[{"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/media?parent=4422598"}],"wp:term":[{"taxonomy":"oen_topic_chapter","embeddable":true,"href":"https:\/\/myendoconsult.com\/learn\/wp-json\/wp\/v2\/oen_topic_chapter?post=4422598"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}