However, MMA levels also rise with renal insufficiency and tend to be higher in older adults. Levels of serum methylmalonic acid (MMA), a vitamin B12-associated metabolite, are the most sensitive markers of vitamin B12 status, and an MMA level greater than 0.271 micromol/L suggests vitamin B12 deficiency. The cutoff between normal vitamin B12 levels and deficiency varies by method and laboratory, but most laboratories define subnormal serum or plasma values as those lower than 200 or 250 pg/mL (148 or 185 pmol/L). Vitamin B12 status is typically assessed by measurements of serum or plasma vitamin B12 levels. If vitamin B12 is added to fortified foods and dietary supplements, it is already in free form and therefore does not require the separation step. The resulting complex is absorbed in the distal ileum by receptor-mediated endocytosis. In the duodenum, digestive enzymes free the vitamin B12 from haptocorrin, and this freed vitamin B12 combines with intrinsic factor, a transport and delivery binding protein secreted by the stomach’s parietal cells. More vitamin B12 is released from its food matrix by the activity of hydrochloric acid and gastric protease in the stomach, where it then binds to haptocorrin. The freed vitamin B12 then binds with haptocorrin, a cobalamin-binding protein in the saliva. The process starts in the mouth when food is mixed with saliva. Vitamin B12 is bound to protein in food and must be released before it is absorbed. L-methylmalonyl-CoA mutase converts L-methylmalonyl-CoA to succinyl-CoA in the metabolism of propionate, a short-chain fatty acid. Methionine is required for the formation of S-adenosylmethionine, a universal methyl donor for almost 100 different substrates, including DNA, RNA, proteins, and lipids. Methionine synthase catalyzes the conversion of homocysteine to the essential amino acid methionine. Vitamin B12 functions as a cofactor for two enzymes, methionine synthase and L-methylmalonyl-CoA mutase. Vitamin B12 is required for the development, myelination, and function of the central nervous system healthy red blood cell formation and DNA synthesis. However, two others forms, hydroxycobalamin and cyanocobalamin, become biologically active after they are converted to methylcobalamin or 5-deoxyadenosylcobalamin. Methylcobalamin and 5-deoxyadenosylcobalamin are the metabolically active forms of vitamin B12. Because vitamin B12 contains the mineral cobalt, compounds with vitamin B12 activity are collectively called “cobalamins”. Vitamin B12 is a water-soluble vitamin that is naturally present in some foods, added to others, and available as a dietary supplement and a prescription medication. For a reader-friendly overview of Vitamin B12, see our consumer fact sheet on Vitamin B12. This is a fact sheet intended for health professionals. Health Risks from Excessive Vitamin B12.Groups at Risk of Vitamin B12 Inadequacy.Please consult your doctor before starting any exercise or nutritional supplement program or before using these or any product during pregnancy or if you have a serious medical condition. These products are not meant to diagnose‚ treat or cure any disease or medical condition. These statements have not been evaluated by the Food and Drug Administration (FDA). Yes‚ these liquid vitamins are THAT great!ĩ8% ABSORPTION RATE: JoySpring B12 for Kids has a 98% absorption rate and a liquid smoothness that never gets stuck on teethĪ MIGHTY MIX: These B12 drops contain a powerful mix of vitamin B2‚ B6‚ and B12 which will support your child's development‚ cardiovascular‚ immune‚ and nervous system while also promoting good digestion. WIN THE VITAMINS & PICKY EATING BATTLE: When toddlers don’t eat right‚ this is the best way to make sure they still get all the B vitamins they need to grow stronger and healthier‚ minus the tantrums or bribing. JUST THE GOOD STUFF: JoySpring's liquid B12 complex is made with a 100% all natural plant-based formula and is free of artificial flavors or additives. Simply drip a few drops into their favorite drink‚ soup or smoothie. LIQUID VITAMINS KIDS LOVE: If your kids don’t like pills‚ nasty gummies or any chewable vitamins‚ JoySpring B12 For Kids is a lifesaver! No bitter aftertaste either.
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