Evidence-Based Nutrient Recommendations

Facts about Supplemental B12


B12 in Supplements is Produced by Bacteria

The vitamin B12 component in B12 supplements and fortified foods is made by bacteria and sourced from bacteria cultures; it’s not taken from animal products. However, some companies might put gelatin in their B12 supplements, though this appears to be uncommon. It’s easy to find vegan B12 supplements on the Internet or in grocery stores in developed countries.

There are some live food supplement companies that rely on spirulina or other algae, rather than bacteria cultures, as a source of B12. You shouldn’t rely on such products for your B12 as testing has indicated it’s not a reliable source of active B12 (more information).

According to Dudko et al. (2022), “Several bacterial species are known for their ability to synthesize vitamin B12 but biotechnological vitamin B12 production today is restricted to Pseudomonas denitrificans and Propionibacterium freudenreichii.” P. freudenreichii has been experimented with to produce B12 in fermented grain products (Xie, 2020).

Streptomyces griseus, a bacterium once thought to be a yeast, was the commercial source of B12 for many years (Linnell, 1984; Code of Federal Regulations, 2001). The bacteria Propionibacterium shermanii has also been used (De Baets, 2000). Rhone Poulenc Biochimie of France reported using a genetically engineered microorganism to produce B12 (private correspondence between Rhone Poulenc Biochimie and Red Star Yeast, 1997).

Avoid Exposing B12 to Light

Prolonged light can damage cyanocobalamin (Schneider, 1987; Linnell, 1984); keep B12 supplements and fortified foods in dark, cold locations.

Brewer’s and Nutritional Yeasts Must be Fortified

Brewer’s and nutritional yeasts don’t contain B12 unless they’re fortified. Since B12 is light-sensitive and nutritional yeast is fairly light-permeable, be sure to keep it in a dark place, preferably refrigerated.

Chew B12-Only Supplements

Crane et al. (1994) noted that tablets of one vitamin company dissolved slowly in water and acid. They conducted a study to see if vegan patients who hadn’t previously responded to swallowing B12 tablets whole could improve their B12 levels by chewing the tablets.

Of 16 participants, 7 chewed tablets of 100 µg once a week for 6 weeks; their average serum B12 levels increased from 86 to 216 pmol/l. Of the 9 who didn’t chew, their serum B12 increased from 91 to only 103 pmol/l. However, a 100 µg dose once a week isn’t much; the more surprising result of this experiment was the large increase in the serum B12 of the 7 people who chewed.

Of the 9 who originally didn’t chew, 7 of them then chewed 500 µg/day for 10 days and their levels rose to normal with a final average of 388 ± 174 pmol/l. Three participants couldn’t raise their levels orally and required B12 injections to maintain serum B12 above 222 pmol/l.

A 2003 study compared 500 µg per day via the sublingual (under the tongue) and oral routes. Sublingual fared no better than oral B12 at raising B12 levels or improving B12 activity (as measured by homocysteine and methylmalonic acid levels). Both routes effectively increased B12 levels (Sharabi, 2003).

B12-Fortified Toothpaste is Reliable

B12-Fortified Toothpaste in Vegans

A 2017 randomized, double-blind, placebo-controlled trial was the first to test the efficacy of B12-fortified toothpaste in raising blood markers of B12 status (Siebert, 2017). The trial was conducted in Germany and included 66 vegans. 22 participants in the placebo group and 31 in the intervention group were taking B12 supplements; they were asked to continue their supplementation behavior throughout the study.

Participants were instructed to use the study-issued toothpaste twice a day, brushing for two minutes each time. The treatment toothpaste contained 100 µg B12/g toothpaste. Researchers estimated participants received 130-290 µg B12 per day via the toothpaste, but were not able to calculate or measure how much B12 the participants absorbed.

At the end of 12 weeks, compared to their baseline values, participants in the intervention group experienced significantly increased B12 (from 197±137 to 279 ± 134 pmol/L; p=0.001) and holotranscobalamin (from 35 ± 35 to 64 ± 34 pmol/L; p<0.001), significantly decreased methylmalonic acid (from 0.303 ± 0.361 to 0.212 ± 0.123 µmol/L; p=0.001), and not-quite-significantly decreased total homocysteine (from 10.6 ± 6.2 to 9.7 ± 6.4 µmol/L; p=0.058). These changes are associated with improved B12 status. Participants in the placebo group did not experience significant changes in their B12 markers between baseline and the end of the intervention.

Based on this study, it appears that B12-fortified toothpaste is a viable source of B12.

B12 Toothpaste in Older Adults

A 2019 randomized, double-blind, placebo-controlled trial assessed the efficacy of B12-fortified toothpaste in a sample of 92 older adults (Zant, 2019). After 3 months, those receiving the treatment toothpaste, containing 100 µg of B12/g of toothpaste, experienced significantly greater B12 levels compared with the placebo group (368 vs. 295 pmol/L; p = 0.005). Researchers concluded that B12-fortified toothpaste may be used to help prevent B12 depletion in older people.

Avoid Cooking all Your B12

Tucker et al. (2000, USA, Tucker, 2000) found that B12 from fortified breakfast cereals and dairy products was associated with better B12 status than was B12 intake from red meat, poultry, and fish, leading the researchers to suspect that the B12 from meat might be damaged by cooking.

The B12 in animal foods tends not to be cyanocobalamin, the form used in fortified foods, that is more stable during cooking. For example, in an acid medium (pH 4-7), cyanocobalamin can withstand boiling at 120° C (Watanabe, 2002). However, we don’t have enough evidence to rely solely on fortified foods that are cooked.

Last Updated October 2021


Crane MG, Sample C, Patchett S, Register UD. “Vitamin B12 studies in total vegetarians (vegans). Journal of Nutritional Medicine. 1994;4:419-430.

Code of Federal Regulations. U.S. Government Printing Office. Vitamin B12. Title 21, Volume 3. Revised. April 1, 2001. CITE: 21CFR184.1945 p. 550.

De Baets S, Vandedrinck S, Vandamme EJ. Vitamins and Related Biofactors, Microbial Production. In: Lederberg J, ed. Encyclopedia of Microbiology, Vol 4, 2nd Ed. New York: Academic Press; 2000:837-853.

Dudko D, Holtmann D, Buchhaupt M. Methylotrophic bacteria with cobalamin-dependent mutases in primary metabolism as potential strains for vitamin B12 production. Antonie Van Leeuwenhoek. 2022 Nov 17. Abstract.

Linnell JC, Matthews DM. Cobalamin metabolism and its clinical aspects. Clin Sci (Lond). 1984 Feb;66(2):113-21.

Schneider Z, Stroinski A. Comprehensive B12. New York: Walter de Gruyter, 1987.

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.

Siebert AK, Obeid R, Weder S, Awwad HM, Sputtek A, Geisel J, Keller M. Vitamin B-12-fortified toothpaste improves vitamin status in vegans: a 12-wk randomized placebo-controlled study. Am J Clin Nutr. 2017 Mar;105(3):618-625.

Tucker KL, Rich S, Rosenberg I, Jacques P, Dallal G, Wilson PW, Selhub J. Plasma vitamin B-12 concentrations relate to intake source in the Framingham Offspring study. Am J Clin Nutr. 2000 Feb;71(2):514-22.

Watanabe, F. Women’s University, Department of Health Science, 5-15 Eikokuji-cho Kochi 780-8515 Japan. Personal communication, March 6-7, 2002.

Xie C. In situ fortification of vitamin B12 in grain materials by fermentation with Propionibacterium freudenreichii. Department of Food and Nutrition. Faculty of Agriculture and Forestry. University of Helsinki Finland. EKT-Series 1950. Doctoral dissertation. August 2020.

Zant A, Awwad HM, Geisel J, Keller M, Obeid R. Vitamin B12-fortified toothpaste improves vitamin status in elderly people: a randomized, double-blind, placebo-controlled study. Aging Clin Exp Res. 2019 Dec;31(12):1817-1825.

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