Vitamin B-12 protects the nervous system. Without it, permanent damage can result (blindness, deafness, dementia). Fatigue, and tingling in the hands or feet, can be early signs of deficiency.
Meat-eaters acquire B12 through micro-organisms living in the animal flesh they eat. Vegetarians can obtain adequate vitamin B-12 from dairy foods, eggs, or fortified foods and supplements, if regularly consumed. For vegans, vitamin B-12 must be obtained from vitamin B12-fortified foods, such as fortified soy and rice beverages, some breakfast cereals and veggie ‘meats’, or fortified nutritional yeast (check the label – fortified brands include Kal, Bob’s Red Mill, Braggs and Red Star Vegetarian Support Formula.) If these foods are not eaten on a regular basis, a daily or weekly vitamin B-12 supplement is needed. In the past, some non-animal items such as spirulina, tempeh, miso, and soil were considered as possible sources, but these have proven to be unreliable.
Vegans should do one of the following:
- Eat fortified foods two or three times – aim for at least 3 mcg (or µg) of B-12 a day – or
- Take a daily B-12 supplement with at least 10 mcg – or
- Take a weekly B-12 supplement providing at least 2000 mcg.
The less frequently you obtain B12 the more B-12 you will need. B-12 is best absorbed in small amounts. The recommendations above this into account. There is no harm in exceeding the recommended amounts or combining more than one option.
In the absence of any apparent dietary supply, deficiency symptoms usually take five years or more to develop in adults, though some people experience problems within a year. Long term studies of vegans have detected a very low rate of B-12 deficiency. Some people (including meat-eaters) have problems absorbing B-12. It’s especially important for women to ensure B12 intake when pregnant or breastfeeding.
It is easy for vegans in Western societies to ensure an adequate B-12 intake. Vegans who supplement with B-12 can have superior B12 status to non-vegetarians who do not supplement. In fact, the United States Food and Nutrition Board says that all people over age 50 (not just vegans) should “meet their RDA mainly by consuming foods fortified with B12 or a B12-containing supplement.” This is due to the fact that those over age 50 have a decreased ability to absorb B-12.
If you have concerns about a nutrient deficiency, you can always have your blood tested. Note: some blood tests are unreliable. The most specific test for B12 status is methylmalonic acid (MMA) testing.
- See B12 section of the American Dietetic Association’s 2009 Vegetarian Position Paper.
- What Every Vegan Should Know about Vitamin B12, veganhealth.org
- Don’t Vegetarians Have Trouble Getting Enough Vitamin B12?, PCRM