By Reed Mangels, PhD, RD

A new study (1) reminds us that vegans should either regularly take a vitamin B12 supplement or eat foods fortified with vitamin B12 daily. This study combined data from 19 smaller studies that examined vitamin B12 status in a total of 930 vegans, 1,019 vegetarians, and 1,166 nonvegetarian adults.

Several indicators of vitamin B12 status were significantly different in vegans compared to nonvegetarians. Vegans had lower serum vitamin B12 concentrations and elevated total homocysteine. Elevated homocysteine indicates that vitamin B12 deficiency is having a negative effect on the function of some body systems that require vitamin B12.

This study also examined 4 smaller studies which compared vegans who used vitamin B12 supplements to vegans who did not use vitamin B12 supplements. Vegans who used vitamin B12 supplements had a better vitamin B12 status than did vegans who did not use vitamin B12 supplements.

These results strongly support the importance of taking a vitamin B12 supplement or eating foods fortified with vitamin B12 if you are following a vegan or a near-vegan diet. The study’s authors recommend that all vegetarians meet their needs for vitamin B12 through fortified foods and supplements.

Vitamin B12 deficiency can lead to lasting damage to the nervous system and to cognitive impairments. In pregnancy and lactation, vitamin B12 deficiency is associated with an increased risk of having a preterm infant, neural tube defects such as spina bifida, developmental delay, and poor growth (2).

Foods that are commonly fortified with vitamin B12 include some plant milks, some breakfast cereals, and some brands of nutritional yeast. Not every brand or every product within a brand may be fortified with vitamin B12. A study published in 2021 found that only 47% of the plant milks that were surveyed in the US were fortified with vitamin B12 (3). It’s important to read labels regularly since fortification practices can change.

Unfortified foods that may be mentioned on websites or in popular literature as containing vitamin B12 such as tempeh, shiitake mushrooms, miso, sourdough bread, and so on, are not reliable sources.

This new study provides a good reminder – don’t forget to take vitamin B12!

References:

1. Niklewicz A, Hannibal L, Warren M, et al. A systematic review and meta-analysis of functional vitamin B12 status among adult vegans. Nutr Bull. Published online October 7, 2024.
2. Obeid R, Murphy M, Solé-Navais P, et al. Cobalamin status from pregnancy to early childhood: Lessons from global experience. Adv Nutr. 2017;8:971-979.
3. Craig WJ, Fresán U. International analysis of the nutritional content and a review of health benefits of non-dairy plant-based beverages. Nutrients. 2021;13:842.

To read more about vitamin B12 see:

Vitamin B12 in the vegan diet

Does the form of vitamin B12 matter?

Is duckweed a reliable source of vitamin B12?