Vegans and those on a 100% plant-based diet need to make sure they have a regular supply of vitamin B12. However there is some controversy over how this should be obtained; whether from fortified foods or supplements – or both, which is the best form of B12 methylcobalamin or cyanocobalamin, how often to take it and at what dose etc.
How common is vitamin B-12 deficiency? Even if you consume animal products it may still be necessary to take a B12 supplement or eat fortified foods as there is no guarantee that you’re actually absorbing enough B12 to prevent deficiency and promote health. A significant proportion of people on the standard UK diet (SUK) and on the standard American diet (SAD) are deficient in B12 (and many other essential nutrients) and a much higher proportion are marginally depleted.
B12 absorption depends on a number of factors including age, the type of B12 consumed, B6 & folate status, gastric acid and intrinsic factor levels, and medications etc. Testing for B12 is notoriously unreliable therefore obtaining sufficient regular B12 from your diet is essential to prevent deficiency and maintain good health.
Vitamin B12 Facts
- Yes, B12 supplements may be necessary for some groups of people (more on this below) especially vegans and those on 100% plant-based diet who should obtain a regular supply of vitamin B12 from fortified foods or supplements, or both.
- Although vitamin B12 tests are unreliable, I still believe in combination, they provide enough information to help avoid serious deficiency. I’m having mine tested roughly once every eighteen months as a rough guide and for my own records.
- Vitamin B12 deficiency is extremely serious and can be disabling and life-threatening. It can take from 10 to 15 years for a serious continuous B12 deficiency to begin to show symptoms, a situation which should be avoided at all costs. If you have any symptoms of B12 deficiency and you believe your diet to be adequate in supplying your needs, then you should see a doctor and get tested for a condition known as pernicious anaemia.
- Methylcobalamin is more readily absorbed (in theory) than cyanocobalamin but is less stable as a product (methylcobalamin is light-sensitive). Cyanocobalamin is less easily absorbed (in theory) but is a very stable product and its the form that’s most often used in clinical trials. Which one to take? Until further research confirms which is the best form to supplement (or maybe yet another form), I take both :-)
- Vitamin B12 is thought to be a very safe supplement partly because it’s water-soluble and excess amounts are excreted in the urine, and also on the basis of many clinical trials showing no adverse reactions. However, recently some doubts have been raised regarding the safety of B12 as a supplement in relation to lung cancer risk largely due to this article: Cancer Incidence and Mortality After Treatment With Folic Acid and Vitamin B12. However, this study combined B12 with folic acid a known carcinogen and personally I think this is the reason why the study showed increased lung cancer risk.
- How much B12 should we take and how often in order to maintain and promote health and avoid deficiency? The RDA for B12 is often quoted as 2.4 µg per day. Orally, we would need to consume around 250 µg per day to stay comfortably above this amount (absorbing approximately 5 µg from 250 µg). Intrinsic factor secreted in the stomach has a limited B12 binding capacity such that higher doses lead to a reduced absorption percentage. Therefore at any given time, taking a dose higher than a few hundred micrograms will not lead to an increase in the amount of B12 absorbed. Taking a regular small dose would appear to be more effective than taking thousands of micrograms infrequently.
- Everyone should understand the importance of vitamin B12 but there are two groups (in addition to vegans and those on a 100% plant-based diet) for which it becomes more critical, these are lactating mothers and people over the age of fifty. For breastfeeding babies it’s essential that the mother has sufficient B12 reserves and a good supply of B12 in her diet to pass on to the baby. For those over the age of fifty regardless of diet it might be worth considering taking a regular low-dose supplement to maintain healthy B12 reserves. As we age B12 absorption declines and apparently past the age of fifty it becomes a greater concern due to declining production of hydrochloric acid in the stomach.
- Long-term vitamin B12 deficiency is a very serious business. Therefore, everyone should assess their vitamin B12 intake and make sure that it’s adequate, especially the two groups I mentioned in ‘7’ above as well as vegans and those on a 100% plant-based diet. Again, whether from animal foods, fortified plant-based foods or from supplements, make sure your regular vitamin B12 intake is sufficient to prevent deficiency and maintain good health.
I hope this brief discussion on vitamin B12 has helped to clarify its importance for health and the prevention of chronic disease and will prompt you to assess your own B12 intake and make sure it’s adequate for your requirements. Personally I take bi-weekly supplements of B12, 1000 µg of cyanocobalamin (sublingual) mid-week and 1000 µg of methylcobalamin at the weekend.
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