Vitamin B12 Recommendations

Step 1

If you have a regular source of B12, skip to Step 2. If you have not had a regular source of B12 for some time, buy a bottle of 1,000 µg (or greater) B12 tablets.

Chew 2,000 µg once a day, for 2 weeks. You can break the remaining tablets in half or quarters for Step #2. It's okay to take more than recommended. Then follow the advice under Step #2.

In rare case, someone might have an acne-like response to such large doses of vitamin B12. If that happens to you, skip to Step 2 and opt for one of the lower dose regimens.

Step 2


  • In foods, B12 is measured in micrograms (aka "µg" or "mcg"). 1,000 µg = 1 mg.
  • The DRI for vitamin B12 is 2.4 micrograms for adults.
  • Fortified foods: Amounts listed on a nutrition label are based on 6 µg/day. For example, 25% of the Daily Value = .25 * 6 µg = 1.5 µg.
  • Do not rely on any seaweed (e.g., algae, nori, spirulina), brewer's yeast, tempeh, or "living" vitamin supplement that uses plants as a source of B12. More info.
  • Do not rely solely on one type of fortified food such as Red Star Nutritional Yeast.
  • The sublingual route (i.e., dissolving the table under the tongue) of taking vitamin B12 is no more effective than just swallowing (4).
  • Vegan infants: The Institute of Medicine recommends that infants of vegan mothers be supplemented with B12 from birth because their stores at birth and their mother's milk supply may be low (3).
  • Exceptions: People with digestive or malabsorption diseases (such as pernicious anemia), chronic kidney failure, B12 metabolism defects, or cyanide metabolism defects should consult a bona fide health professional.
  • Cigarette smokers should consider a non-cyanocobalamin source of B12. Click here for more information.

Click here for an explanation of how these recommendations were formulated.


1. Lower limit based on minimum recommendations in What Every Vegan Should Know about Vitamin B12.

2. In a single dose, B12 absorption drops to 1-1.5% for the amounts above 5 µg.

3. Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academy Press; 2000.

4. Sharabi A, Cohen E, Sulkes J, Garty M. Replacement therapy for vitamin B12 deficiency: comparison between the sublingual and oral route. Br J Clin Pharmacol. 2003 Dec;56(6):635-8. | link