Studies: Iron and vitamin B12 supplements help optimize the nutrient profile of a vegetarian diet

If your nutrient intake is not in line with your body's needs, this can lead to deficiencies – regardless of whether your diet is exclusively plant-based or includes meat. However, it is widely acknowledged that vegans should make a special effort to ensure they are getting enough of the water-soluble vitamin B₁₂. This comes down to the fact the vitamin is found almost exclusively in animal products.

In December 2019, the status of vitamin B₁₂ as a critical nutrient for vegans was confirmed by a study showing that vegans who did not take vitamin B₁₂ supplements were at greater risk of having low vitamin B₁₂ plasma levels than vegans who did. The researchers found that the risk of a vitamin B₁₂ deficiency was tied to a lack of B₁₂ supplementation rather than the length of time the subjects had been following a vegan diet.

It is vital to pay particular attention to ensuring a good supply of iron; in fact, low iron levels are the most common type of nutrient deficiency worldwide. Although vegetarians and vegans appear to ingest similar amounts of iron to non-vegetarians by eating wholegrain products and legumes, the body only absorbs 10% of the iron in plant-based foods at most. By contrast, 30% to 70% of the iron in meat is heme iron, which has an absorption rate of 15% to 30%. There are, however, some exceptions: iron from curry leaves and certain mushrooms is highly bioavailable.

In 2018, a systematic review yielded fresh insights into the effects of vegetarian diets on iron status. Generally speaking, we tend to attribute iron deficiency to women more than men, not least as a result of pregnancy and menstruation. Interestingly enough, however, a meta-analysis of the data showed that the differences in iron stores (ferritin levels) between male vegetarians and male non-vegetarians were more pronounced than those between female vegetarians and female non-vegetarians. This could be attributable to the fact that the iron stores of non-vegetarian men are generally higher than those of non-vegetarian women and therefore become depleted to a greater extent after the switch to a vegetarian diet. Despite this, women have a higher risk of iron deficiency and iron deficiency anemia and should therefore keep a close eye on their iron supplies.

A carefully planned vegetarian and vegan diet provides all the nutrients you need to keep your body healthy. Nevertheless, it does make it harder to secure sufficient supplies of certain nutrients, such as iron and vitamin B₁₂, vitamin D and omega-3 fatty acids. Vegans and vegetarians may benefit from special supplements to facilitate their daily nutrient intake.