Writing in the European Journal of Nutrition, researchers in Germany conducted a double-blind randomized controlled trial (RCT) to evaluate the nutrient status of vegans before and after four months of multinutrient supplementation. They determined that the supplement, containing 82 mg of vitamin B12 taken daily, positively impacted vitamin B12 blood biomarkers in healthy vegans. Comparatively, an average multivitamin has 5 to 25 mg of B12 per serving.
“As there are currently no standardized reference values for sufficient vitamin B12 intake via supplements, these results might help to establish vitamin B12 intake recommendations for vegans,” the researchers wrote. “In contrast, no clear positive impact of the multinutrient supplement on nutrient status could be demonstrated for all other examined vitamins and choline, leading to the assumption that the participants were already adequately supplied with these nutrients.”
They also explored the impact of other critical vitamins on the vegan population and concluded that vegans meeting most nutritional benchmarks may need additional supplementation for vitamins A and B2.
The research was conducted by scientists from the Institute of Nutritional Sciences (Justus-Liebig University), the Research Institute for Plant-Based Nutrition, MVZ Medical Laboratory (Bremen), Institute for Prevention and Cancer Epidemiology (IPE), and the Medical Center-University of Freiburg. The study was primarily funded by Watson Nutrition, a Berlin-based brand offering supplements tailored for vegan, vegetarian and plant-based diets.
The researchers wrote that a previous multinutrient intervention study with vegans was conducted in the 1960s and that to the best of their knowledge the current clinical study is the first of its kind targeting the population.
Critical supplements
Vegan diets are increasing in popularity. In Germany, approximately 3% of the population considers themselves vegan. Certain nutrients are critical for this group like vitamin D, vitamin B2, iron, zinc, iodine, selenium, calcium and choline and should be supplemented by vegans if not adequately found in their dietary practices, the researchers wrote. Moreover, conversion rates from α-linolenic acid to docosahexaenoic acid (DHA) are typically low in the population because there is lack of omega-3 fatty acid consumption.
When it comes to vitamin B12, which is found naturally in animal products, the researchers noted that it is a primarily accepted view that vitamins should be supplemented when “adhering to vegan or near-vegan diet unless an adequate intake of this vitamin is ensured via fortified food” and that a variety of nutrient supplements designed for vegans are on the market.
Vegans may also have lower levels of vitamin A, a nutrient found in animal products and in certain plants and non-animal foods, leading to hypercarotenaemia (caused by excessive ingestion of carotene-rich foods) in some individuals genetically predisposed to the condition.
Study details
Eighty-eight adults participated in the study, including some individuals who reported consuming meat, meat products or eggs no more than three times a month. The intervention group took one capsule a day of a multinutrient supplement (which contained vitamin B2, vitamin B12, vitamin D3, vitamin K2, calcium, iodine, iron, selenium and zinc), an omega-3 supplement also containing vitamin D3 and vitamin E (two capsules daily) and a choline supplement in powder form at each meal during the study.
The researchers asked the participants to maintain their typical dietary habits during the investigation and to keep a dietary record throughout it. Only a small percentage of participants took additional supplements, considered allowable within the study’s guidelines.
The scientists assessed what they deemed critical nutrients. This included testing for biomarkers for vitamin A, vitamin B2 and vitamin B12 to determine participant vitamin deficiencies.
“After four months of multinutrient supplementation, there were no significant changes in the relevant parameters of vitamin A status between the groups [experimental and control],” the researchers explained.
They also suggested that administering a multinutrient supplement with 743 mg of vitamin A could marginally maintain vitamin A levels, but it might not significantly improve the vitamin’s status within four months.
Participants’ generally poor vitamin A levels indicate that doses within a multinutrient should be higher. The researchers wrote that B2 status should be similarly considered. That vitamin is mostly found in meat, poultry, fish and dairy, though has some plant sources as well.
However, over 75% of participants appeared to have adequate status for most nutrients.
The researchers emphasized that a lack of improvement in vitamin A and B2 levels may be because of a decrease in bioavailability in the supplement and/or not enough of the nutrient. As for vitamin B12, the scientists wrote that it “is regarded as the most critical nutrient in vegan diets, so the observed change in vitamin B12 status with vitamin B12 supplementation compared to placebo was to be expected.”
Source: European Journal of Nutrition. Doi: 10.1007/s00394-025-03814-7 “Assessment of vitamin A, vitamin B2, vitamin B12, vitamin K, folate, and choline status following 4 months of multinutrient supplementation in healthy vegans: a randomised, double-blind, placebo-controlled trial”. Authors: Tim Zerback et al.
