What is it?
Vitamin B12, also known as cobalamin is an essential vitamin and is produced by microorganisms in the soil as well as the gut of animals and humans. However, in humans, the location where the intestinal bacteria thrive in the colon is beyond the site of vitamin B12 absorption. This makes vitamin b12 an essential vitamin for humans, meaning that unlike other vitamins, our body cannot synthesise (create) it and therefore we must consume it from our diet.
What does it do?
Vitamin B12 is important in keeping a healthy nervous system, which includes helping the synthesis of DNA, involved in cell division and maintaining the myelin sheath that is wrapped around our nerve cells.
Where is it found?
Vitamin B12 is predominately found in animal products, this includes red meats, poultry, seafood, dairy products and eggs. Due to the restriction of these foods due to health, ethical and environmental reasons from a vegan or vegetarians diet, this becomes a particular nutrient of concern for individuals following these diets. There have been studies that have found small amounts of vitamin b12 found in white button mushrooms and Korean purple laver (nori) however these foods only contains an extremely small amounts of Vitamin B12 and therefore does not contribute largely to the daily requirement of this vitamin. There are also other plant foods such as spirulina, fermented soy, tempeh and miso which claim to be a source of vitamin B12 however, these foods contain the INACTIVE form of vitamin B12 which can be more detrimental to health as the body cannot utilise it this form, and it also interferes with the absorption of the active form.
There are a number of foods in Australia that have been fortified (have added) with vitamin B12. These include some soy milks, vegetarian faux meats, burgers and sausages.
Can I become deficient?
Yes, you can become deficient, however, our vitamin B12 levels are tightly regulated and it may take an extended period of time for deficiency to appear. It is important to note that unless symptoms are detected and treated early, symptoms can be irreversible. Deficiency in B12 can cause serious health consequences such as megaloblastic anaemia, demyelinisation of nerves, severe brain damage, memory loss and psychosis. It is especially important for pregnant or lactating women to ensure they are consuming enough Vitamin B12 to ensure they provide enough for their developing baby.
How much do I need?
Table 1 – Nutrient Reference Values of Vitamin B12
Table 1 indicates the Nutrient Reference Values (NRV) of Vitamin B12 for Australia and New Zealand. It is important that everyone, especially those following a vegan or vegetarian diet ensure that they consume an adequate and reliable source of vitamin B12 from supplementation and/or fortified foods to meet the RDI.
So How Can I Consume Enough Vitamin B12?
For people following a vegan diet, the only way to consume a reliable sourc
e of Vitamin B12 is through eating fortified food or using a supplement. Supplementation should be achieved through tablets taken daily that meet the RDI (refer to table 1). It is also important to note that the body is only able to absorb a small amount of Vitamin B12 at any one time and therefore it is recommended that small amounts and frequent daily doses are the most effective, in comparison to infrequent large doses including intramuscular injections. Consuming fortified foods in addition to supplementing is also beneficial. The type of Vitamin B12 found in these foods is easily absorbed by the body, often to a greater extent than the Vitamin B12 in meat, poultry and seafood. However, these meat analogues are often highly processed and therefore should not be considered as the sole source of Vitamin B12.
Zeuschner, C. L., Hokin, B. D., Marsh, K. A., Saunders, A. V., Reid, M. A., & Ramsay, M. R. (2013). Vitamin B₁₂ and vegetarian diets. The Medical Journal of Australia, 199(4 Suppl), S27-S32.
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Jndar Koyyalamudi, R. A. O., Jeong, S., Yip Cho, K. A. I., & Pang, G. (2009). Vitamin B12 is the active corrinoid produced in cultivated white button mushrooms (agaricus bisporus). Journal of Agricultural and Food Chemistry, 57(14), 6327-6333. doi:10.1021/jf9010966
Miyamoto, E., Yabuta, Y., Kwak, C. S., Enomoto, T., & Watanabe, F. (2009). Characterization of vitamin B12 compounds from korean purple laver (porphyra sp.) products. Journal of Agricultural and Food Chemistry, 57(7), 2793-2796. doi:10.1021/jf803755s
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