Do I need vitamin B12 on a plant-based diet?

Vitamin B12, also known as cobalamin, is one the 8 essential B vitamins, meaning our body cannot make it. It is essential for metabolism, the production of red blood cells, making DNA and protecting our nerve cells. 

Vitamin B12 is not made by plants or animal, but by bacteria. As our hygiene practices have evolved, the amount of bacteria we consume has significantly reduced, making it more difficult to get enough vitamin B12. Cows and chickens get enough vitamin B12 as they eat off the ground where the bacteria can be found, and that is where meat eaters get it from. However, as our animal farming practices are becoming more hygienic too, the animals’ food often requires vitamin B12 fortification. 

Some bacteria in our gut also produce vitamin B12. However, as it is produced further down the gastrointestinal tract in the colon and is absorbed further up in the ilium, it is usually not immediately available for absorption.

On a whole food plant-based or vegan diet, vitamin B12 can be found in nutritional yeast, and some unhealthy, fortified vegan foods. However, if relying on nutritional yeast as a source of vitamin B12, you would need to consume 2 teaspoons, 3 times per day minimum. This is not very practical for most people, which is why it is recommended to obtain it from a supplement.

What happens if you don’t get enough?

For anyone following a whole food plant-based or vegan diet, it is absolutely necessary to supplement vitamin B12. Vitamin B12 deficiency is not to be messed around with, it can be very harmful. It can take years before someone is diagnosed with vitamin B12 deficiency as it can be stored in the liver for about 2 years. It can result in megaloblastic anaemia, a condition resulting in the production of abnormal, immature red blood cells. Symptoms include fatigue, muscle weakness and a swollen tongue. Deficiency can also result in irreversible nerve damage, leading to symptoms of strange sensations, numbness, tingling of hands, legs and feet, difficulty walking, cognitive difficulties and memory loss.

How much do I need and where can I get it on whole food, plant-based diet?

The recommended daily intake for adult men and women in Australia is 2.4 micrograms per day[1]. However, the absorption is quite complicated and therefore, in supplement form it is required in much greater quantities. It is recommended to take either one 50-100 microgram supplement per day or 2000 micrograms per week (e.g. 2 x 1000 microgram supplement tablets per week)[2].

Vitamin B12 supplements come in many forms; cyanocobalamin, methycobalamin, hydroxycobalamin and adenosylcobalamin. It is recommended to take it in the form of cyanocobalamin, as it is less prone to being destroyed when exposed to light and there is more research into its efficacy. Vitamin B12 from a multivitamin is not recommended as various vitamins and minerals mixed into the pill can destroy vitamin B12, therefore it is less effective[3].

Ideally, obtain vitamin B12 in sublingual, chewable tablet or liquid form rather than a pill you swallow as it is more effective when it has been exposed to saliva.

Summary

-Vitamin B12 supplementation is essential to anyone avoiding animal products

-Vitamin B12 deficiency can take years to develop, and it can be very harmful 

-Recommendations for supplement: either 50 micrograms per day or 2000 micrograms per week in the form of cyanocobalamin, ideally in chewable, sublingual or liquid form.

[1] National Health and Medical Research Council. (2018). Vitamin B12. https://www.nrv.gov.au/nutrients/vitamin-b12

[2] Rizzo, G., Laganà, A. S., Rapisarda, A. M. C., Ferrera, L., Grazia, G. M., Buscema, M., ... & Vitale, S. G. (2016). Vitamin B12 among vegetarians: status, assessment and supplementation. Nutrients, 8(12), 767.

[3] Obeid, R., Fedosov, S. N., & Nexo, E. (2015). Cobalamin coenzyme forms are not likely to be superior to cyano‐and hydroxyl‐cobalamin in prevention or treatment of cobalamin deficiency. Molecular nutrition & food research, 59(7), 1364-1372.