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About Active Vitamin B12


Vitamin B12 (cobalamin), along with its various active forms or coenzymes (hydroxocobalamin, methylcobalamin and adenosylcobalamin), is one of the main water-soluble vitamins. In blood, a part of cobalamin binds to the protein transcobalamin to be transported to the body's cells. This leads to what we call “Active vitamin B12”, named Holotranscobalamin, which can be measured in blood.

Vitamin B12 is involved in many metabolic processes in the body. It also promotes the normal nervous system and brain function, the formation of epithelial cells in the intestine, and the normal development and function of red and white blood cells. Vitamin B12 is also involved in the synthesis of DNA and nucleotides. It is needed in folate activation and the building process of phospholipids in cell membranes. In addition, vitamin B12 is involved in synthesizing succinyl-CoA, an intermediate in the citric acid cycle. It is, therefore needed for energy metabolism.

Vitamin B12 can have an impact on sports performance. It is considered to be an important nutrient for athletes as it helps support energy metabolism and is important for blood health. It also assists in the utilization of proteins, carbohydrates and fats. The research proposes that poor levels of vitamin B12 are correlated with a decreased ability to perform high-intensity exercises.

THE BEST FOOD SOURCES OF VITAMIN B12 (source: the Fineli database)
• Beef liver (110 mcg / 100 g)
• Reindeer liver (84 mcg / 100 g)
• Kidney (24 mcg / 100 g)
• Canned mussel (22 mcg / 100 g)
• Chicken liver (21 mcg / 100 g)
• Baltic herring fillet (14.9 mcg / 100 g)
• Warm smoked salmon (10 mcg / 100 g)
• Roe, average value (9.5 mcg / 100 g)
• Reindeer steak (7.1 mcg / 100 g)
• Pickled herring (7 mcg / 100 g)
• Elk and reindeer meat (6.3 mcg / 100 g)
• Trout and rainbow trout (5 mcg / 100 g)
• Warm smoked whitefish (4.8 mcg / 100 g)
• Organic egg, boiled (2.7 mcg / 100 g)
• Beef sirloin (2.3 mcg / 100 g)
• Pike perch, pike, roach, redfish (2 mcg / 100 g)
• Cheese, average value (1.8 mcg / 100 g)

Vitamin B12 occurs in dietary supplements, mainly as cyanocobalamin or methylcobalamin. Some products contain a slightly rarer form, adenosylcobalamin, which is the form vitamin B12 takes inside cells. Vitamin B12 injections, available by prescription, contain cyanocobalamin. Methylcobalamin on the other hand comes in a bioactive form—it is significantly more easily absorbed via the digestive tract compared to cyanocobalamin. Methylcobalamin also has a more comprehensive effect on the body compared to cyanocobalamin.

Biostarks reference ranges for active vitamin B12

  • Active Vitamin 12 (VitB12-S): 25.1-165 pmol/L.

Scientific references:

  • Nexo, E., & Hoffmann-Lücke, E. (2011). Holotranscobalamin, a marker of vitamin B-12 status: analytical aspects and clinical utility. The American journal of clinical nutrition, 94(1), 359S-365S.
  • Čabarkapa, V., Stošić, Z., Žeravica, R., Ilinčić, B., & Filipović, A. (2007). The importance of holotranscobalamin measurement. Journal of Medical Biochemistry, 26(3), 227-230.
  • Loikas, S. et al. (2007). Vitamin B12 deficiency in the aged: a population-based study. Age and Ageing 36 (2): 177–183.
  • O'Leary, F., & Samman, S. (2010). Vitamin B12 in health and disease. Nutrients, 2(3), 299–316.
  • Kozyraki, R., & Cases, O. (2013). Vitamin B12 absorption: mammalian physiology and acquired and inherited disorders. Biochimie, 95(5), 1002-1007.
  • Douaud, G., Refsum, H., de Jager, C. A., Jacoby, R., Nichols, T. E., Smith, S. M., & Smith, A. D. (2013). Preventing Alzheimer’s disease-related gray matter atrophy by B-vitamin treatment. Proceedings of the National Academy of Sciences, 110(23), 9523-9528.
  • Higdon, J. (2015). Vitamin B12. Linus Pauling Institute. Micronutrient Information Center.