Why do we need B12?
Vitamin B12 is needed for cell division and blood formation. Although recommendations for it are very small, deficiency is a very serious problem leading ultimately to anemia and irreversible nerve damage. (Vegetarian Resource Group) Symptoms include excessive tiredness, breathlessness, listlessness, pallor, and poor resistance to infection. When deficiency occurs, it is more commonly linked to a failure to effectively absorb B12 from the intestine rather than a dietary deficiency. (Vegetarian Society)
How much B12 does one need?
The requirement for vitamin B12 is very low (about 2-3 micrograms per day), however it is especially important for pregnant and lactating women, infants, and children to have reliable sources of it in their diets. (Vegetarian Resource Group). You can get a test to check out your levels of B12.
Why is it hard for vegans to get B12?
Plant foods do not contain vitamin B12, thus vegans need to look to fortified foods or supplements to get it in their diet (Vegetarian Resource Group).
B12 comes from our soil. When a cow, for instance, chomps on grass she eats this enriched soil. There are also microorganisms located in the animal's intestine that produce Vitamin B12...Our food today is usually very clean by the time it makes it to our stores, and then we further clean it in our own kitchen. Goodbye Vitamin B12. (Vegan Coach)
Are there different types of B12?
Yes. There is "true" B12 and inactive analogues. Vegan Health has a great article on measuring B12.
There are also different forms of B12, the major types being: Methylcobalamin (the primary form found in the human body), Cyanocobalamin (most commonly found in vitamin supplements), Hydroxycobalamin and Adenosylcobalamin. You can read more about each of them on this Buzzle.com page.
Do vegans have to take supplements to get B12?
Not necessarily. You may be able to get it by eating nutritional yeast, fortified cereal, fortified soy milk, fortified meat analogues, seaweed, or algae. However, some analysis shows that the soy and algae may not have significant amounts. Instead they contain analogs of B12 that are not active and may actually block the absorption of true vitamin B12. Be wary of labels that say "excellent sources of B12", as that might just be marketing. Carefully read the labels and see if the product contains the daily amount needed. (Vegetarian Nutrition)
If you'd like to take a supplement make sure it does not contain animal products like gelatin. Check out DEVA tablets and JARROW, Methyl B-12. In order to meet your needs, you should take a daily vitamin B12 supplement of 5-10 micrograms or a weekly supplement of 2000 micrograms. (Vegetarian Resource Group) Some suggest that B12 supplements should be thoroughly chewed for better absorption. (Vegetarian Nutrition)
Jump to minute 9 of this video for more info:
Are spirulina and nutritional yeast good sources of B12?
- The B12 content of spirulina is not significant enough to count as a good source (Vegetarian Society). Studies have shown that spirulina (and some soy products) contain predominantly B12 analogues, which is not a true source of the vitamin. (Beyond Vegetarianism)
- One brand of nutritional yeast, Red Star T-6635+, has been tested and shown to contain active vitamin B12. About 2 rounded teaspoons of it provides the recommended amount of vitamin B12 for adults (Vegetarian Resource Group) **make sure it says that it is fortified with B12**