Thursday, March 25, 2010
People who convert to a vegan diet from one of consuming animal products are in no immediate danger of vitamin B12 deficiency (assuming they were healthy to begin with). Our body stores it fairly long term and only requires a small amount of intake to be okay. The problems are when there is low intake of B12, or some kind of absorption issue. The result of insufficent B12 is developing pernicious anemia, nerve damage (ie. dementia, blindness, deafness), and high homocysteine levels which could contribute to heart disease. The early signs of B12 problems are fatigue, tingling of the hands or feet, or digestive problems.
Because of our modern food sourcing, vegans should really supplement B12, and that can mean taking a vegan vitamin or consuming fortified cereals, soy products, and non-dairy milks. Because B12 comes from bacteria, there is no problem finding vegan vitamin sources. There is a nutritional yeast that also offers B12, but it's hard to consider it reliable for several reasons mostly having to do with storage. Other products such as seaweed, mushrooms, algae, and some fermented foods are reported to contain B12, but the levels are so minimal and unreliable that it is not recommended for vegans to rely solely on non-fortified foods. Most nutritionists say that since there doesn't appear to be a problem with taking excess B12, it is better to err on the side of caution, and supplement. Sublingual tablets or sprays, and even injections are not required to obtain adequate levels of B12. Any Vitamin B12 tablet or multivitamin with sufficient micrograms of B12 should suffice. I personally choose to take a supplement because it is easier than worrying about consuming enough fortified foods on a daily basis.
From Dr. Stephen Walsh at VegFamily:
"To get the full benefit of a vegan diet, vegans should do one of the following:
~Eat fortified foods two or three times a day to get at least three micrograms (mcg or g) of B12 a day or
~Take one B12 supplement daily providing at least 10 micrograms or
~Take a weekly B12 supplement providing at least 2000 micrograms.
If relying on fortified foods check the labels carefully to make sure you are getting enough B12. For example, if a fortified plant milk contains 1 microgram of B12 per serving then consuming three servings a day will provide adequate vitamin B12. Others may find the use of B12 supplements more convenient and economical."
If you are worried about your vitamin B12 levels due to low intake or absorption problems, or if you want to get a baseline for future checks, you may consider getting some tests done to measure your B12. Jack Norris, RD at Vegan Health reports the following:
A blood B12 level measurement is a very unreliable test for vegans, particularly for vegans using any form of algae. Algae and some other plant foods contain B12-analogues (false B12) that can imitate true B12 in blood tests while actually interfering with B12 metabolism. Blood counts are also unreliable as high folate intakes suppress the anemia symptoms of B12 deficiency that can be detected by blood counts. Blood homocysteine testing is more reliable, with levels less than 10 mmol/litre being desirable. The most specific test for B12 status is methylmalonic acid (MMA) testing. If this is in the normal range in blood (370 nmol/L) or urine (less than 4 mg /mg creatinine) then your body has enough B12. Many doctors still rely on blood B12 levels and blood counts. These are not adequate, especially in vegans.
More info on B12 testing, Vegan Health.
More Vitamin B12 Info
*Vegetarian and Vegan Foundation: B12 and the Vegan Diet
*Veg Family: What Every Vegan Should Know About Vitamin B12
*Vegan Health: Vitamin B12
*International Vegetarian Union: Nutrition- Vitamin B12