FUNCTIONS As co-enzymes, the B vitamins are essential components in most major metabolic reactions. They play an important role in energy production, including the metabolism of lipids, carbohydrates, and proteins. B vitamins are also important for blood cells, hormones, and nervous system function. As water-soluble substances, B vitamins are not generally stored in the body in any appreciable amounts (with the exception of vitamin B-12). Therefore, the body needs an adequate supply of B vitamins on a daily basis. Thiamin, riboflavin, and niacin are all essential coenzymes in energy production. Thiamin is converted quickly into thiamin pyrophosphate, which is required for glycolytic and Krebs cycle reactions. Thiamin also appears to be related to nerve impulse transmission. Riboflavin is a component of the coenzymes FAD and FMN, which are intermediates in many redox reactions, including energy production and cellular respiration reactions. Niacin is also a component of the coenzymes NAD and NADP, which are involved in energy production, as well as biosynthetic processes. Vitamin B-6 is a coenzyme in amino acid metabolism. It is necessary for the metabolism of homocysteine and the conversion of tryptophan into niacin. Vitamin B-6 dependent enzymes are also needed for the biosynthesis of many neurotransmitters, including serotonin, epinephrine, and norepinephrine. Methylcobalamin (vitamin B12) and folate are coenzymes in DNA and RNA metabolism. Both of these B vitamins assist in homocysteine metabolism. Folate serves as a methyl donor and methylcobalamin as a coenzyme in the conversion of homocysteine to methionine. Studies indicate that methylcobalamin, a coenzyme form of B12, may be better utilized and better retained in the body. Metafolin® ® is a patented, natural form of (6S) 5- methyltetrahydrofolate (5-MTHF). 5-MTHF is the naturally occurring, predominant form of folate commonly found in cells and is essential for overall health, as it participates as a cofactor in a reaction that involves the remethylation of homocysteine to methionine. Unlike synthetic folic acid, 5-MTHF can be used directly by the body, without the need for an additional conversion via the enzyme (5,10-methylenetetrahydrofolate reductase (MTHFR)). In certain populations, the body’s ability to convert folic acid to 5-MTHF by use of this enzyme may be compromised due to genetic differences. Metafolin® contains only the S isomer of 5-MTHF and has been shown to be the only form of folate to be able to cross the blood-brain barrier. Biotin and pantothenic acid are also coenzymes essential for energy production from dietary fats, carbohydrates, and proteins. Pantothenic acid is a component of coenzyme A and of phosphopantetheine, and is therefore essential for Krebs cycle operation. Biotin is involved in many carboxylation reactions associated with gluconeogenesis, the Krebs cycle, and fatty acid synthesis. REFERENCES Quadros EV Br J Haematol. 2010 Jan;148(2):195-204. Epub 2009 Oct 12. Review. Hvas AM, et al. Jun;91(6):805-8. Epub 2006 May 16. Pietrzik K, Bailey L, Shane B. Clin Pharmacokinet. 2010 Aug 1;49(8):535-48 Mahadeo KM, et al. GeneReviews [Internet]. Seattle (WA): University of Washington, Seattle; 1993-.2008 Jun 17 [updated 2010 May 06]. Helga Refsum and Keith M. Circulation 2006;114;1193-1201; originally published online Aug 28, 2006 Andersen CB, Madsen M, Storm T, Moestrup SK, Andersen GR. Nature. 2010 Mar 18;464(7287):445-8 Depeint F, et al. Chem Biol Interact. 2006 Oct 27;163(1-2):94-112. Kräutler B. Biochemistry of B12-cofactors in human metabolism. Subcell Biochem. 2012;56:323-46. doi: 10.1007/978-94-007-2199-9_17. Wang YP, et al. Physiol Res. 2014;63(3):341-50. Keith ME, et al. J Am Diet Assoc. 2009 Aug;109(8):1406-10. doi: 10.1016/j.jada.2009.05.011. Das UN. 2015 Feb;31(2):283-291. doi: 10.1016/j.nut.2014.08.011. Morris MS. Adv Nutr. 2012 Nov 1;3(6):801-12. doi: 10.3945/an.112.002535. Jacobs AM, Cheng D. Rev Neurol Dis. 2011;8(1-2):39-47. Lea R, et al. Pharmacogenet Genomics. 2009 Jun;19(6):422-8. Miller AL. Altern Med Rev. 2003 Feb;8(1):7-19. Shakir KM, et al. Mayo Clin Proc. 1995 Jun;70(6):556-8. Ulvik A, et al. Am J Clin Nutr. 2013 Oct;98(4):934-40. doi: 10.3945/ajcn.113.064998. Schaeffer MC, Gretz D, Gietzen DW, Rogers QR. J Nutr. 1998 Oct;128(10):1829-35. Liu Z, Choi SW, Crott JW, Smith DE, Mason JB. Int J Cancer. 2008 Aug 1;123(3):519-25. doi: 10.1002/ijc.23599.
