Micronutrients

Vitamin B12 for vegans

from Mag. Margit Weichselbraun
on 16.06.2024
Vegan with a good vitamin B12 status Vegan with a good vitamin B12 status

Vitamin B12, also known as cobalamin, should be used by people with a lacto-vegetarian or vegan diet. As a vegan or vegetarian with low milk and egg consumption, there is an increased risk of developing a deficiency. What are the sources of plant-based vitamin B12? Do I have to supplement in addition to a balanced plant-based diet? What is my need for vitamin B12? Find out all about the water-soluble vitamin here.

Vegan diet: Balanced and well planned

The key to a balanced vegan diet is diversity. The well-planned consumption of fresh vegetables, fruit, whole grain products, legumes, nuts, oilseeds and high-quality oils not only allows you to provide yourself with sufficient protein, vitamins and minerals, but also means you benefit from the numerous health-promoting fibres and phytonutrients.

However, special attention should be paid to the supply of vitamin B12. As this vitamin is found mainly in foods of animal origin, it is recommended that vegans use targeted supplements or fortified foods to avoid a deficiency. With careful planning and proper supplementation, a vegan diet can be varied, nutritious and health-boosting.

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Good cobalamin sources for vegans and vegetarians

While ovo-lacto vegetarians can specifically nourish their vitamin B12 balance with animal products, as they consume eggs and dairy products, vegans, lacto vegetarians and raw food eaters in particular should pay attention to a sufficiently high vitamin B12 intake. In addition to enriched foods, special vitamin B12 preparations containing the vitamin in usable forms can support daily absorption.

Vitamin B12 in plant-based foods

If you’re looking for plant-based sources, you’ll find it in chlorella. Unlike other algae, chlorella contains predominantly usable vitamin B12. However, due to their very low B12 content, chlorella algae are not recommended as the sole source of B12 in a purely plant-based diet. Other plant-based foods, commonly referred to as sources of vitamin B12, contain only inactive vitamin B12 analogues . Apart from that, only bacterially fermented plant-based foods – such as sauerkraut – or shiitake mushrooms contain traces of vitamin B12.

Vitamin B12 products for vegan nutrition

Preparations that contain natural, usable forms are ideal for filling up with vitamin B12. These include methylcobalamin and adenosylcobalamin – but also hydroxycobalamin, which can be stored very well by the body. Once you start looking more closely at the plethera of food supplements, you will notice that these products are available in very different dosages on the market.

While the absorption is active with small amounts of vitamin B12 and passive diffusion hardly plays a role in healthy persons, absorption is almost exclusively passive at higher doses of vitamin B12 – whereby only a fraction of the amount ingested is passively absorbed into the body (~ 1-4% of the amount of vitamin B12 ingested).

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Should vitamin B12 be supplemented if you are a vegan?

While most micronutrients are abundant in vegan diets, a vitamin deserves special attention – vitamin B12 (cobalamin), which practically does not occur in plant-based foods and only occurs in small amounts. In order to still achieve an appropriate vitamin B12 intake, vegans are encouraged to use vitamin B12 supplements or fortified foods.

Vegan and still well supplied? To date, experts around the world continue to argue about this. However, in-depth nutritional knowledge is undoubtedly an important prerequisite for a well-planned and needs-based vegan diet. The basis of a vegan diet should be a varied selection of fruit and vegetables, grain and soya products, legumes, nuts and seeds. In addition, a reliable vitamin B12 preparation should be used and it should be ensured whether the need for iodine, calcium, vitamin D, iron, omega 3 fatty acids and protein is met through food. 

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Determination of vitamin B12 supply

A regular check of the vitamin B12 status is recommended for vegans and vegetarians in order to detect a deficiency early. Here, the standard vitamin B12 value in the blood serum alone is not sufficient, since it is a relatively late and non-specific marker. Instead, further diagnostic values should be used, which in combination provide a more reliable picture.

  • Holotranscobalamin (Holo-TC): An important parameter is the active form holotranscobalamin II (Holo-TC). Holo-TC represents the active fraction of the vitamin and, as the earliest biomarker, it may indicate an imminent vitamin B12 deficiency. If this value drops below 35 pmol/l, this is a warning sign. Current studies confirm that the Holo-TC measurement correlates better with the symptoms of undersupply than the vitamin B12 serum values and should therefore be established as the most important biomarker.
  • Methylmalonic acid (MMA): The marker methylmalonic acid (MMA) increases in the blood and urine when the vitamin B12 levels are exhausted. Accordingly, MMA is a functional marker that provides information about the availability of vitamin B12  Values above 271 nmol/l indicate a manifest deficiency.

A combined analysis of these parameters provides reliable information about the vitamin B12 supply. For vegans, it is therefore recommended that a detailed blood test should be carried out at least every 2-3 years in order to be able to take timely action if the supply is not optimal.

Supplementation recommendation for vegans and vegetarians

For vegans, it is important to target their vitamin B12 needs with supplements or fortified foods. The German Nutrition Society (DGE) recommends a daily intake of 4 micrograms (μg) vitamin B12 for adults.

This value is based on the assumption that the vitamin is absorbed several times a day in small amounts via food. The active absorption of vitamin B12 from a single dose is limited to approximately 1.5-2 μg per meal. The remaining portion that is not actively absorbed is only absorbed 1-4% via passive diffusion.

Adequate vitamin B12 intake is essential for vegans and vegetarians to prevent deficiencies. However, when supplemented once daily due to plant-based diets, the body uses the passive absorption pathway for the vitamin and therefore higher doses are necessary because this passive diffusion is less efficient. This should be taken into account when planning B12 supplementation in plant-based diets.

Vitamin B12 deficiency in vegan or vegetarian diets

It is estimated that around 75 million people around the world have opted for a vegetarian diet. In addition, there are around 1.45 billion people who have to live as de facto vegetarians because of a lack of alternatives. A strictly vegetarian (vegan) diet that completely avoids foods of animal origin provides a maximum of 0.5 micrograms of vitamin B12 per day. This makes this form of diet one of the main risk factors for vitamin B12  deficiency. However, even vegetarians who consume dairy products and eggs often experience subclinical deficiencies, which manifest as elevated levels of methylmalonic acid or homocysteine in the blood. Children of vegan or strictly vegetarian mothers can also be affected by a vitamin B12 deficit. Therefore, it is advisable for vegetarians of all forms to have a regular test for a possible vitamin B12 deficiency.

To the blog post: Vitamin B12 deficiency

Further reading:

Rizzo G et al. 2016. Vitamin B12 Among Vegetarians: Status, Assessment and Supplementation. Nutrients. 2016 Nov 29;8(12):767.

Schüpbach R et al. Micronutrient Status and Intake in Omnivores, Vegetarians and Vegans in Switzerland. Eur J Nutr. 2017 Feb;56(1):283-293.

Gallego-Narbón A et al. Vitamin B 12 and Folate Status in Spanish Lacto-Ovo Vegetarians and Vegans. J Nutr Sci. 2019 Feb 26;8:e7.

Selinger E et al. Vitamin B12 Deficiency Is Prevalent Among Czech Vegans Who Do Not Use Vitamin B12 Supplements. Nutrients. 2019 Dec 10;11(12):3019.

Obersby, D. et al. 2013. Plasma total homocysteine status of vegetarians compared with omnivores: a systematic review and meta-analysis. Br J Nutr. 109(5):785–94.

Deutsche Gesellschaft für Ernährung. 2018. Vitamin B12 (Cobalamine).

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