Vitamin B12 for vegans

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.

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).

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.

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.

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.