Health  |  Nutrition  |  Vegan

Mythbusting: “How A Vegan Diet Could Affect Your Intelligence”

March 26, 2020  |  By: Whitney E. RD

A recent article published by the BBC claims that vegan diets can be detrimental to brain health – so naturally, there has been a lot of speculation on this topic. What’s the truth when it comes to vegan brain health? Today I’m answering this question and explaining the science behind it.

Recently, the BBC posted an article on their website titled, “How a Vegan Diet Could Affect Your Intelligence”. I’m here to set the facts straight and debunk the sensationalized, biased and blatantly false claims laid out in this article.

This is one of several opinion pieces written by the BBC in the past year not-so-subtly attacking a plant-based diet. Typically, I would prefer not to call attention to articles that are pure nonsense, like this one, but in this case, I felt it was important to address the claims and falsities as I know many people have questions about them.

I also want to demonstrate the importance of using a critical eye when reading news articles. This is an example of how a seemingly reputable outlet can publish an astonishingly inaccurate opinion piece under the guise of journalism by cherry-picking studies and lying by omission.

The piece is biased, poorly researched, and in some cases, flat out factually inaccurate. Let’s start with what the author got completely wrong.

VITAMIN B6

The article claims that to get the daily minimum required amount of vitamin B6 – a micronutrient important for cognitive development and immune function – vegans would have to eat about 5 cups of potatoes a day.

The RDA for B6 is 1.3 mg a day for adults. According to the USDA national nutrient database, one large russet potato contains over 1 mg of vitamin B6. Since a large potato equates to about 2 cups chopped, you’d have to eat about 2 cups of potatoes to meet the RDA – not 5 cups. 

However, you don’t have to eat any potatoes if you don’t like them. B6 is widespread in a plant-based diet – good sources include pistachios, fortified cereal, and chickpeas. If your family is eating a balanced plant-based diet, you’re easily meeting your B6 needs.  

IRON

Next, the article claims the typical vegan diet is “scarce” in iron. They reference a study that found that participating vegans were consuming 40% less iron than the recommended daily amount. This cherry-picked study is easily refutable, as the bulk of research shows there is no significant difference in iron intake between plant-based eaters and omnivores. In fact, some studies have shown that plant-based dieters often consume more iron than omnivores.

While it is true that plant-based, non-heme iron is less bioavailable than the heme iron found in animals, the reduced absorption can be overcome by pairing high iron foods with vitamin C rich foods. Vitamin C has shown to increase the absorption of plant-based iron as much as 3 to 6 times for every 50 mg of vitamin C added to a meal.

Finally, though vegans and vegetarians generally have lower iron stores, research has not shown that plant-based adults have a higher incidence of iron deficiency. Iron is the number one nutrient deficiency for adults and children of all dietary patterns. 

Therefore, it’s important that everyone focuses on incorporating iron-rich foods in their diet, and plant-based dieters should employ strategies to maximize iron absorption. This isn’t hard though. Most plant-based dieters naturally pair iron and vitamin C-rich foods together like oatmeal and strawberries, beans and bell peppers, or leafy greens and grains. 

Folate

Another false claim in the article is that folate is a nutrient of concern for vegans. This is incorrect and shows the author’s blatant lack of nutritional knowledge. Plants are the top sources of folate in the diet. 

In fact, one study showed folate concentrations were highest among vegans, intermediate among vegetarians, and lowest among omnivores.

Choline

The last glaring inaccuracy I want to point out here is about choline. The article states that soy does not contain choline.

It’s actually one of the best dietary sources of choline with ½ cup of soybeans providing 117 mg of choline. Eggs, one of the best animal sources of choline, only have about 30 mg more per egg.

Vegan diets and brain health

Now let’s talk about the arguments the author uses to make the case that a vegan diet is bad for brain health. First, they cite a study of Kenyan school children that aimed to compare the cognitive effect of adding a serving of meat, milk, vegetable oil, or nothing (the control group) to the children’s daily diet. 

Results showed the children in the meat group performed the best, followed by the control group, then the oil group, and then the milk group. The BBC author attempted to equate this study to a comparison of omnivorous, vegetarian, or vegan diets. There are just so many issues with this study and the author’s attempt to extrapolate the results to vegan diets.

The biggest issue is that meat, milk, and oil are incredibly nutritionally different. It’s like comparing apples to orangutans. Meat is an excellent source of iron, an important nutrient for brain health (though remember as we just talked about – plants contain plenty of iron too).

Milk, on the other hand, is a very poor source of iron. Not only is it extremely low in iron, the calcium in milk actually inhibits iron absorption and kids who drink too much milk are more likely to be iron deficient. Oil contains zero iron. However, it does not inhibit iron absorption.

See the common denominator here? It’s iron. The children eating meat likely did the best because they received additional iron in their diet, not because they received meat. The milk group, despite receiving more protein than the oil and both more calories and more protein than the control group, likely did worse because milk inhibits iron absorption.

A smart study would have used an isocaloric amount of soy instead of oil for comparison as it contains protein, fat, and iron and is more nutritionally equivalent to meat.

Finally, many of the Kenyan children in this study had stunted growth and ranged from moderately to severely underweight. It’s simply not appropriate to compare a population of malnourished children to those consuming a well-planned plant-based diet.

The BBC author should have found a study that looked at adding meat to a nutritionally adequate diet, alas no such study exists.

Next, the author points out a few nutrients that are absent or low in vegan diets.

B12 and brain health

First up, B12.

The article emphasizes the health-risks of B12 deficiency and the commonality of B12 deficiency among the plant-based population.

They are absolutely correct that B12 deficiency can cause serious, irreversible damage to the brain but what they gloss over is the fact that B12 deficiency is easily prevented with supplementation.

Let me make this clear – all plant-based dieters, vegan, vegetarian or otherwise – should supplement with b12. Supplementing with B12 is a simple, affordable way to avoid deficiency, and anyone following a properly-planned vegan diet already does this, which negates the author’s argument. 

Choline and brain health 

Next up, choline.

I’ve already pointed out the author’s error in stating that soy doesn’t contain choline – but let’s explore this claim further. The author argues that a vegan diet is low in choline and therefore harmful to brain health.

She cites a study showing that high choline supplementation during pregnancy improved infants’ reaction times. First, this study was not conducted on plant-based dieters and second, it’s unclear if a well-planned vegan diet actually has less choline than an omnivorous diet.

While it is true that choline during pregnancy is important, the truth is that the majority of people do not eat enough choline – both vegans and omnivores. The results of the study on choline during pregnancy highlight the importance of maternal choline intake, which is why many prenatal multivitamins now include it.

We recommend that all adults and children ensure proper choline intake one of two ways: by regularly eating eggs and or soy foods or by supplementing, especially during pregnancy and lactation. 

For more information on choline, check out my post Choline on a Plant-Based Diet!

CREATINE AND BRAIN HEALTH

Creatine is another nutrient of concern the author lists.

Creatine is a chemical naturally found in our muscles and brain, and it is one of the body’s sources of energy for muscle contraction. The thing is – our bodies have the ability to make creatine. While it is generally accepted that vegans and vegetarians have lower amounts of creatine in their skeletal muscle, the same is not true for the brain.

One study, linked directly by the author, shows that dietary creatine intake does not change how much creatine is in the brain because the brain relies on its own synthesis of creatine. This makes me think the author didn’t even read the study before drawing her erroneous conclusion.

TAURINE AND BRAIN HEALTH

Lastly, the author makes the claim that taurine is another nutrient of concern in a vegan diet.

Taurine is a non-essential amino acid that is involved in a variety of biological and physiological functions such as bile salt formation, retinal development, and electrolyte balance. The author states that because taurine is low in plant-based diets, this could have a negative effect on brain health and cognitive ability. 

However, our bodies make taurine, and while studies show that vegans do have a lower plasma content, there is substantial evidence that renal taurine excretion adapts to dietary taurine intake. Meaning if you eat less, you store more.

Taurine is only considered an essential amino acid for preterm infants, who typically receive dietary taurine through breast milk or infant formula. While studies show vegan mothers have a lower amount of taurine in their breast milk, there is no research showing signs of taurine deficiency in babies breastfed by vegan mothers.

There is also currently no conclusive evidence that a lack of taurine in the diet has any clinical manifestations for vegans. I will note that there is some evidence that taurine supplementation may be beneficial for people with cardiovascular disease, but more research is needed to make any recommendations.

BENEFITS OF A VEGAN DIET

And that’s that – as you see, the author is quick to make false, unfounded, or exaggerated claims about vegan diets and brain health. Additionally, the author fails to mention the plethora of proven health benefits that come with a plant-based eating pattern.

Properly planned plant-based diets have been shown to reduce all-cause mortality and the risk of cardiovascular disease, diabetes, and obesity. Studies show that vegan and vegetarian diets may also decrease cancer risk.

In fact, plant-based diets may actually have positive effects on brain health. Studies show plant-based diets are associated with lower blood pressure. Recent studies have linked persistent hypertension to mild cognitive impairment, which is a major risk factor for the development of dementia. 

Plant-based diets have also been shown to decrease incidence of atherosclerosis, the fatty plaque that can build up in your arteries, which is also a risk factor for the development of vascular dementia. Finally, several studies suggest diabetes is a contributing risk factor for the development of Alzheimer’s disease, and plant-based diets lower the risk of diabetes.

It’s scary that an organization like BBC would allow an article riddled with factual inaccuracies to even be published, but I hope this round-up has eased any fears you may have about a plant-based diet and brain health and provided you with some tools to use the next time you encounter a sensationalized article like this one.

Always aim to get your information from credible, qualified nutrition professions – and remember, if an article sounds biased, it probably is.

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Weigh-in: Have you heard other outlandish claims about plant-based diets? Do you feel better prepared to determine the credibility and biases of a source?