NUTRITION HOTLINE
By Reed Mangels, PhD, RD
QUESTION: Do vegans have to take vitamin B12 supplements?
ANSWER: Vegans, just like other vegetarians and nonvegetarians, need to have reliable sources of vitamin B12. Reliable sources for vegans are foods fortified with vitamin B12 and vitamin B12 supplements. Fortified foods — foods that have vitamin B12 added to them — include some brands of plant milks, some vegan meats, some breakfast cereals, some energy bars, some tofu, some nutritional yeast, and various other foods. Most multi-vitamins contain vitamin B12 and it is available as a stand-alone supplement also. To find out if a food is fortified with vitamin B12, check the nutrition label — added vitamin B12 will be indicated. If vegans’ vitamin B12 intake from food sources is adequate, supplements are not needed, although it is important to be sure that fortified food sources are reliable, adequate, and used daily.
The table below shows the amount of vitamin B12 in some foods.
Clearly, a person drinking 2 cups of fortified soymilk (2 x 1.2 = 2.4 mcg) or choosing other fortified foods could achieve the levels of vitamin B12 recommended by the Dietary Reference Intakes (2.4 mcg/day is the Recommended Daily Allowance (RDA) for an adult). The low amounts of vitamin B12 added to fortified foods helps with absorption; 60% of low dose (less than 5 mcg) of vitamin B12 is absorbed.1
If supplements are used, be aware that the amount absorbed is reduced, the higher the dose of the supplement. About 5% of the vitamin B12 in a supplement containing 25 mcg of vitamin B12 is absorbed.2-4 A lesser amount, 1% or less, of the vitamin B12 in a supplement containing more than 100 micrograms of vitamin B12, is absorbed.1,3 Vegan registered dietitians Jack Norris, RD and Virginia Messina, MPH, RD recommend that if vitamin B12 supplements are used, you should take either a 25-100 microgram supplement once a day or a 1000 microgram supplement three times a week.5
For more about vitamin B12, refer to Jack Norris, RD's excellent webpage: Vitamin B12 - Are You Getting It? http://veganhealth.org/articles/vitaminb12
| Food | Vitamin B12 (micrograms per serving) |
|---|---|
| Veggie "meat analogs," fortified, 1 oz | 1.0 - 3.0 |
| Soymilk, fortified, 1 cup | 1.2 - 2.9 |
| Protein bar, fortified, 1 bar | 1.0 - 2.0 |
| Nutritional yeast, Vegetarian Support Formula, 1 Tbsp | 4.0 |
| Marmite yeast extract, 1 tsp | 0.9 |
References
1. Institute of Medicine, Food and Nutrition Board: Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B-6, Folate, Vitamin B-12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academy Press, 1998.
2. Heyssel RM, Bozian RC, Darby WJ, Bell MC. Vitamin B12 turnover in man: the assimilation of vitamin B12 from natural foodstuff by man and estimates of minimal daily dietary requirements. Am J Clin Nutr. 1966;18:176–84.
3. Berlin H, Berlin R, Brante G. Oral treatment of pernicious anemia with high doses of vitamin B12 without intrinsic factor. Acta Med Scand. 1968;184:247–58.
4. Adams JF, Ross SK, Mervyn L, Boddy K, King P. Absorption of cyanocobalamin, coenzyme B 12, methylcobalamin, and hydroxocobalamin at different dose levels. Scand J Gastroenterol. 1971;6:249–52.
5. Norris J, Messina V. Vegan for Life. DaCapo Press, 2011.
