Vitamin B12 (as cyanocobalamin)

Vitamin B12 is an essential water-soluble vitamin that is commonly found in a variety of animal foods such as fish, shellfish, meat and dairy products 1, 2, 3, 4, 5. Synthetic vitamin B12 is frequently used in combination with other B vitamins in vitamin B complex formulations 2 and is added to supplements and fortified foods such as cereals 1, 2, 3, 4, 5. Vitamin B12 is needed for normal blood formation and neurological function 1. Vitamin B12 helps form red blood cells (RBC) and maintain the central nervous system (spinal cord, brain) 3, 6. An adequate supply of vitamin B12 is essential to maintain healthy nerve cells and helping with the production of the body’s genetic material, RNA and DNA 7, 8. Vitamin B12 helps also with red blood cell function 6, folate utilization 2, 9, and in normal protein 3, fat and carbohydrate metabolism 2. Vitamins B12, B9, and B6 work together to control blood levels of homocysteine 7.

Higher levels of vitamin B12 intake have been associated with improved cognitive function in elderly subjects 10. Another requirement of vitamin B12 is for the synthesis of S-adenosylmethionine (SAMe), which is required as a methyl donor in various methylation reactions in the brain 8. This compound, SAMe, produced from vitamins B12 and B9 (Folate), is involved in immune function and mood 7.

No adverse effects have been associated with vitamin B12 intake from food or supplements in healthy individuals 1. The U. S. Food and Drug Administration (FDA) has established a Reference Daily Intake (RDI) of 6 µg vitamin B12 for adults and children 4 or more years of age (which will change in the year 2020 to 2.4 mcg) (21CFR101.9) 11, 12, 13. RDIs are a set of dietary references for essential vitamins and minerals that are considered amounts sufficient to meet the daily requirements of healthy individuals 4, 11, 13. RDIs serve as the basis for calculating the percent daily value (%DV) amounts found on dietary supplement and food labels 4, 12, 13.

Cyanocobalamin is the principal form of vitamin B12 for commercial use in fortified foods and dietary supplements 1, 2, 4. According to the FDA, cyanocobalamin is generally recognized as safe (GRAS)(21CFR184.1945) 14. Once absorbed through the intestine, it is converted to the active forms of vitamin B12 (methylcobalamin and adenosylcobalamin) in the body 1, 4, 15, 16. Adenosylcobalamin is an essential cofactor (helper molecule) in known reactions 17.

This ingredient can be found in the following products in United States:


  1. Food and Nutrition Board (FNB). Institute of Medicine (IOM). Dietary Reference Intakes (DRIs) for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline (2000). Washington, DC: National Academy Press, 2000. and
  2. Natural Medicines database. Professional monograph. Product ID no. 926. Last reviewed 2/22/2019. Last updated 2/19/2019. Subscription required.,-herbs-supplements/professional.aspx?productid=926
  3. U. S. National Library of Medicine (NLM). National Institutes of Health (NIH). MedlinePlus. Vitamin B12. Last updated 1/28/2019.
  4. U. S. Department of Health and Human Services (HHS). National Institutes of Health (NIH). Office of Dietary Supplements (ODS). Vitamin B6. Fact Sheet for Health Professionals. Updated 11/29/2018.
  5. Watanabe, F. Vitamin B12 sources and bioavailability. [Abstract]. Exp Biol Med (Maywood). 207;232(10): 1266-1274.
  6. Johnson, LE. Vitamin B12 (Cobalamins). Merck Manual: l Professional Version. Merck & Co., Inc: Kenilworth, NJ. Full Review/Revision 3/2018. On-line access.,-dependency,-and-toxicity/vitamin-b-12?query=Vitamin%20B12
  7. Penn State Hershey. PennStateHealth. Milton S. Hershey Medical Center. Health information library. Supplements. Vitamin B12 (Cobalamin). Reviewed 10/19/2015 by Steven D. Ehrlich, NMD. A.D.A.M. (a division of EBIX). and
  8. Hanna S, Lachover L, Rajarethinam RP. Vitamin B12 deficiency and depression in the elderly: Review and case report. Prim Care Companion J Clin Psychiatry 2009;11(5):269-270.
  9. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  10. Walker JG, Batterham PJ, Mackinnon AJ, Jorm AF, Hickie I, Fenech M, Kljakovic M, Crisp D, Christensen H. Oral folic acid and vitamin B-12 supplementation to prevent cognitive decline in community-dwelling older adults with depressive symptoms—the Beyond Ageing Project: a randomized clinical trial. Am J Clin Nutr 2012;95(1):194-203.
  11. Dietary Supplement Label Database. National Institutes of Health (NIH). A joint effort of the Office of Dietary Supplements (ODS) and the National Library of Medicine (NLM).
  12. U. S. Food and Drug Administration (FDA). Dietary Supplement Labeling Guide: Appendix B. Daily Values for Adults and Children 4 or more years of age. Last updated: 3/21/2018.[18].
  13. U. S. Department of Health and Human Services (DHHS). National Institutes of Health (NIH). Office of Dietary Supplements (ODS). Strengthening knowledge and understanding of dietary supplement. Health information. Daily Values (DVs).
  14. U. S. Food and Drug Administration (FDA). Electronic Code of Federal Regulations (eCFR). 21CFR 184.1945. Vitamin B12. [50 FR 6341, 2/15/1985] eCFR data current as of 2/6/2019. and
  15. Mahmood L. The metabolic processes of folic acid and vitamin B12 deficiency. Review article. J Health Res Rev 2014;1(1):5-9.
  16. BMJ 2014;349:g5226. Clinical Review. Vitamin B12 Deficiency. Correspondence to A Hunt or
  17. Wallig MA, Keenan KP, in Haschek and Rousseaux’s Handbook of Toxicologica Pathology (Third Edition), 2013. Safety assessment including current and emerging issues intoxicologic pathology. Cobalamin (Vitamin B12). or