Food and Behaviour Research

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Nutrient deficiency risks associated with veganism, study finds: ‘Vitamin B12 is well supplemented, iodine is a matter of concern’

Katy Askew

vegan diet

People who follow strict vegan diets – excluding intake of all animal-based foods - have an increased risk of iodine deficiency, BfR researchers have found.


For the related research article please see:

Previous studies have shown iodine intakes to be insufficent in many people. The richest dietary sources of iodine are fish, seafood (including some seaweeds) and milk or other dairy products - so not only vegan diets, but ANY diet low in these foods raises risks for deficiency.

Iodine is essential to make thyroid hormones, so deficiencies can seriously impair physical and mental health at any age.

But iodine deficiency in pregnancy is particularly serious, as this can permanently impair brain development and function in the unborn child.  In fact, according to UNICEF, the W.H.O and other international organisations:

  • 'Iodine deficiency is the world's most prevalent, yet easily preventable, cause of brain damage'

For a list of other recent news items on Iodine and its importance, see:

And for further information on the topic of 'plant-based diets' (which can have some health benefits, but MUST be properly planned and supplemented to provide all essential nutrients if NO animal foods are included) please see:
11/11/2020 - Nutraingredients

A study carried out by the German Federal Institute for Risk Assessment (BfR) has examined the differences between vegan and mixed diets, concluding ‘Vitamin B12 is well supplemented, iodine is a matter of concern’.

People who follow strict vegan diets – excluding intake of all animal-based foods - have an increased risk of iodine deficiency, BfR researchers have found.

The research project, ‘Risks and benefits of a vegan diet’, saw a BfR research team investigate the nutrient supply in 36 people following a vegan diet and 36 people with a mixed diet. The BfR research team analysed blood and urine samples and evaluated lifestyle questionnaires and dietary protocols.

"This study makes it possible to compare a vegan diet with a mixed diet with regard to a variety vitamins and trace elements," explained BfR President Professor Andreas Hensel.

They detected ‘no significant difference’ with regard to vitamin B12, a nutrient often cited as a concern for vegans because it occurs naturally in meat, dairy and eggs. BfR found B12 was present at approximately the levels in blood samples taken those following vegan and mixed diets.

BfR stipulated that an awareness of possible B12 deficiency allowed vegans to compensate through supplementation. Since B12 is taken up almost exclusively by animal food, the supply of participants following a vegan diet could be due to the intake via dietary supplements,” the official risk assessment body suggested.

Indeed, according to the BfR’s assessment of lifestyle questionnaires, vegans are more active in their use of nutraceuticals to ensure a balanced diet. Of those participating, almost all those following a vegan diet and one third following a mixed diet took different food supplements.

But while vegans were found to compensate for an anticipated lack of B12 in their diet, lower levels of iodine were a cause for concern. Professor Hensel elaborated: "Both diets investigated revealed a lack of iodine. However, the shortage is clearly more distinct in the vegan variant."

The majority of the participants were found to have an iodine deficiency – and the deficiency was ‘significantly more pronounced’ among vegans.

In one third of the vegans who participated, the iodine level was below 20 micrograms per litre (μg/L), the limit defined by the World Health Organization (WHO). Anything below this represents a serious shortage, BfR noted.

A vegan diet has, however, also shown health benefits, such as a higher fibre intake and lower cholesterol levels, BfR stressed.