On vegan diets and brain nutrients—some unsettling research reports in a (surprisingly) still murky research area

Meat and Eggs, by Felix Vallotton, 1918 (via Wikiart).

The vegan diet is low in—or, in some cases, entirely devoid of—several important brain nutrients. Could these shortcomings be affecting vegan’s ability to think?

‘. . . The idea that avoiding meat is bad for our brains makes some intuitive sense; anthropologists have been arguing about what our ancestors ate for decades, but many scientists think that there was a lot of bone-crunching and brain-slurping on the road to evolving these remarkable 1.4kg (3lb) organs. Some have even gone so far as to say that meat made us human.

‘One reason is that intelligence is expensive—the brain devours about 20% of our daily calories, though it accounts for just 2% of our body weight—and what better way to find the enormous array of fats, amino acids, vitamins and minerals these fastidious organs require, than by feasting on animals which have already painstakingly collected or made them.

‘But though it’s hard to imagine our ancestors choosing turnips over tuna, today it’s a different story. According to the latest statistics, there are around 375 million vegetarians on the planet. In the West, veganism has ditched the hippie stigma to become one of the fastest-growing millennial trends; in the United States, it grew by 600% between 2014 and 2017. Meanwhile in India, meat-free diets have been mainstream since the 6th Century BCE.

‘On the one hand, recent concern about the nutritional gaps in plant-based diets has led to a number of alarming headlines, including a warning that they can stunt brain development and cause irreversible damage to a person’s nervous system. Back in 2016, the German Society for Nutrition went so far as to categorically state that—for children, pregnant or nursing women, and adolescents—vegan diets are not recommended, which has been backed up by a 2018 review of the research. In Belgium, forcing a vegan diet on your offspring could land you a spell in prison.

But on the other, if abstaining from meat had any real impact on our brains, you would think that we would already have noticed. So is it really damaging our intellects, or is this all just fear of the unknown?

‘. . . [A study of Kenyan schoolchildren that suggested that meat consumption gives children a cognitive edge] does raise intriguing questions about whether veganism could be holding some people back.

‘In fact, there are several important brain nutrients that simply do not exist in plants or fungi. Creatine, carnosine, taurine, omega-3, haem iron and vitamins B12 and D3 generally only occur naturally in foods derived from animal products, though they can be synthesised in the lab or extracted from non-animal sources such as algae, bacteria or lichen, and added to supplements.

‘Others are found in vegan foods, but only in meagre amounts; to get the minimum amount of vitamin B6 required each day (1.3 mg) from one of the richest plant sources, potatoes, you’d have to eat about five cups’ worth (equivalent to roughly 750g or 1.6lb). . . .

‘For all of the nutrients listed above, vegetarians and vegans have been shown to have lower quantities in their bodies. In some cases, deficiency isn’t the exception—it’s completely normal.

For now, the impact these shortcomings are having on the lives of vegans is largely a mystery. But a trickle of recent studies have provided some clues—and they make for unsettling reading.

‘. . . One of the most well-known challenges for vegans is getting enough vitamin B12, which is only found in animal products like eggs and meat. Other species acquire it from bacteria which live in their digestive tracts or faeces . . . .

‘In children, the consequences of B12 deficiency can be life-altering. “There are some tragic cases of children whose brains failed to develop because of their parents being ill-informed vegans,” says Benton. In one example, the child was unable to sit or smile. In another, they slipped into a coma.

‘Later in life, the amount of B12 in a person’s blood has been directly correlated with their IQ. In the elderly, one study found that the brains of those with lower B12 were six times more likely to be shrinking.

‘Even so, low B12 is widespread in vegans. One British study found that half of the vegans in their sample were deficient. In some parts of India, the problem is endemic—possibly as a consequence of the popularity of meat-free diets.

‘Another nutrient that’s scarce in the typical vegan diet is iron. Though we often associate it with blood, iron also plays prominent role in brain development, and is essential for keeping the organ healthy throughout our lives. For example, one 2007 study found that giving young women iron supplements led to significant intellectual gains. In those whose blood iron levels increased over the course of the study, their performance on a cognitive test improved between five- and seven-fold, while participants whose haemoglobin levels went up experienced gains in their processing speed.

‘Up to two billion people are thought to have a shortage of [iron] worldwide, making it the most common nutritional inadequacy. Vegans are particularly prone, because the form that’s most readily absorbed by the body is “haem iron”, which is only found in animal proteins. One German study found that 40% of the vegans they looked at were consuming less than the recommended daily amount.

‘Other common deficiencies among vegans include D3, omega-3, selenium, folate and iodine. . . . Of course, some of these things can easily be acquired from supplements. But others are so obscure, vegans are unlikely to have even heard of them—let alone realise they could be missing out. . . .

In fact, the holes in our current understanding of what the brain needs to be healthy could potentially be a major problem for vegans, since it’s hard to artificially add a nutrient to your diet, if scientists haven’t discovered its worth yet.

‘. . . Take choline: in the brain, it’s used to make acetylcholine, which is involved in a number of tasks, including relaying messages between nerve cells. It’s fundamental to our ability to think—even insects have it in their tiny brains—and the body can’t produce enough of it on its own.

‘And yet: “It’s a very understudied nutrient,” says Wallace. “I believe we’ve only considered it essential [something you have to get from your diet] since the late 1990s.”

‘There are small amounts of choline in lots of vegan staples, but among the richest sources are eggs, beef and seafood. . . . Wallace points to a 2018 study, which found that the babies of women who consumed twice the amount considered “adequate”—around 930mg each day—in the last third of pregnancy enjoyed a lasting cognitive edge. For comparison, the average vegetarian gets roughly a fifth of that amount.

‘In other cases, our understanding is even murkier. . . .’

Read the whole article by Zaria Gorvett at the BBC, How a vegan diet could affect your intelligence, 28 Jan 2020.

Related ILRI research on the role of meat, milk and egg consumption in the first 1,000 days of life is reported on here:

Journal article

Alonso, S., Dominguez-Salas, P. and Grace, D. 2019. The role of livestock products for nutrition in the first 1,000 days of life. Animal Frontiers 9(4): 24–31.

ILRI slide presentations

Grace, D., Dominguez-Salas, P. and Alonso, S. 2017.

The influence of livestock-derived foods on the nutrition of mothers and infants in developing countries during the first 1,000 days. Presented at a Land O’Lakes/ILRI workshop on animal source foods for nutrition impact, Nairobi, Kenya, 4 May 2017. Nairobi, Kenya: ILRI.

Alonso, S., Lannerstad, M., Dominguez-Salas, P. and Grace, D. 2018.

The influence of livestock-derived foods on nutrition in the first 1,000 days of life: Research report launch. Presented at the Agriculture Nutrition and Health Academy Week, Accra, Ghana, 26 June 2018. Nairobi, Kenya: ILRI.

ILRI brief

Grace, D., Dominguez-Salas, P., Alonso, S., Lannerstad, M., Muunda, E., Ngwili, N., Omar, A., Khan, M. and Otobo, E. 2018.

The influence of livestock-derived foods on nutrition during the first 1,000 days of life. ILRI Policy Brief 25. Nairobi, Kenya: ILRI.

ILRI-Chatham report

Grace, D., Dominguez-Salas, P., Alonso, S., Lannerstad, M., Muunda, E., Ngwili, N., Omar, A., Khan, M. and Otobo, E. 2018.

The influence of livestock-derived foods on nutrition during the first 1,000 days of life. ILRI Research Report 44. Nairobi, Kenya: ILRI.

See also

Lora Iannotti on livestock and animal-source foods at Berlin’s Global Forum for Food and Agriculture, ILRI News blog, 6 Mar 2018.