Why is Vitamin B12 so Important to our Health?
Vitamin B12 (or cobalamin) is a vitamin that is essential to human health. Its function is to act as a cofactor for enzymes, meaning that vitamin B12 must be present for these enzymes to be active. In this capacity, vitamin B12 is needed for the following:
- Formation of red blood cells in the bone marrow
- Synthesis of DNA
- Metabolism of fatty acids and amino acids
- Neurological function (synthesis of myelin sheaths)
Because vitamin B12 is required for all of these processes, a B12 deficiency can cause dysfunctional red blood cells and neurological symptoms.
Vitamin B12 is found in animal products like meat, fish, eggs and dairy, but not naturally found in any plant sources. Vitamin B12 is only created by microbes that are present in the soil or aquatic environments. These B12-producing microbes are transferred to grazing animals like cows or are taken into plankton and accumulate in fish. Some foods are fortified with this vitamin.
Absorbing Vitamin B12 from Food and Supplements
Vitamin B12 that is naturally found in food is bound to protein. In the stomach, the acidic environment releases the vitamin from food and it is transferred to binding proteins. Supplements and fortified foods with added B12 contain free vitamin B12 that does not need to be digested by stomach acids. The B12-binding protein complexes are recognised by a section of the small intestine and absorbed. Upon absorption, B12 enters the bloodstream bound to the transcobalamin transport protein. It takes between 3-4 hours from the time B12 foods are ingestion until it is in the bloodstream.
The body can absorb approximately half of a 1 µg dose of B12 at once. The total amount of B12 absorbed increases with higher doses, but the percentage absorbed decreases as the dose increases. This capacity to absorb B12 is replenished approximately every 4-6 hours. Excess B12 is stored in the liver which can store enough this vitamin for up to a few years. A vitamin deficiency occurs when these stores are depleted, and new B12 is not being absorbed.
Measuring Vitamin Status with Blood Tests
Direct measurement of vitamin B12 is the most common single biomarker to test for B12 deficiency. Low serum B12 levels are a good indicator of deficiency, and high levels indicate that there is sufficient B12 in circulation. Results in the intermediate range, as seen on laboratory results report, mean that there is uncertainty in determining your nutritional status. Dietary interventions are recommended to improve serum B12 levels in the intermediate or low zones. Holo-transcobalamin (TC) is another marker of B12 status, however, studies that have investigated the use of holo-TC show similar specificity and sensitivity to vitamin B12.
Frequency of Low Vitamin B12
At Lykon, approximately 4% of our users are deficient for vitamin B12 (<145 pmol/L). This means they are not getting enough B12 for their body to function optimally and may lead to symptoms in the future. An additional 20% of Lykon users have insufficient (or intermediate) B12 levels, where it is possible that their body is already not getting enough B12 or they are on their way to a deficiency. Overall, almost 1 in 4 users should take measures to improve the B12 content in their diets!
There are many reasons for vitamin B12 levels to decrease. The next article in this series discusses the symptoms and causes of vitamin B12.
Part 2: Vitamin B12 Deficiency
… or check out our biomarker test kits to measure your B12 levels!
Vitamin B12 in Health and Disease. Nutrients. 2010 Mar; 2(3): 299–316.
Cobalamin and folate evaluation: measurement of methylmalonic acid and homocysteine vs vitamin B(12) and folate. Clin Chem. 2000 Aug;46(8 Pt 2):1277-83.
Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Institute of Medicine (US) Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline. Washington (DC): National Academies Press (US); 1998.
Yamada K. (2013) Cobalt: Its Role in Health and Disease. In: Sigel A., Sigel H., Sigel R. (eds) Interrelations between Essential Metal Ions and Human Diseases. Metal Ions in Life Sciences, vol 13. Springer, Dordrecht
Vitamin B12 Deficiency (Cobalamin). Treasure Island (FL): StatPearls Publishing; 2019 Jan-.
Vitamin B12 sources and microbial interaction. Exp Biol Med (Maywood). 2018 Jan; 243(2): 148–158.
Measurement of total vitamin B12 and holotranscobalamin, singly and in combination, in screening for metabolic vitamin B12 deficiency. Clin Chem. 2006 Feb;52(2):278-85.