Top Diets for Brain Health: Keto? Carnivore? Vegan?

From vegan to carnivore: What actually helps the brain?

By Austin Perlmutter, MD

Brain Food!

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Diet plays a crucial role in brain structure, function and our overall brain health. From physically becoming our brain cells to altering neurotransmitters, brain immunity, metabolism and neuroplasticity, every bite of food can be a vote for or against our current and future brain wellness. But diet conversations are also fraught with sensationalism, conflicts of interest and unhelpful complexity. Today, we’re exploring four of the most popular diets to unpack their specific impact on brain health. From carnivore to keto to veganism and more, there’s lots to unpack, and to be clear, this is a brain-focused conversation, so we will center on what we know specifically about the potential for these diets to influence things like dementia, mood and cognition in general.

1.    Vegan Diet

A vegan diet eliminates all animal products, focusing instead on plant foods that include fruits, vegetables, grains, nuts, and seeds. Like many more restrictive diets, veganism has a vocal following who advocate for its compelling benefits to human health. Vegans will also often emphasize the benefit to animal welfare that can be an added (or central) value proposition to this dietary pattern.

Pros: A vegan diet can emphasize a diversity of nutrients associated with better brain health. Plant-based foods are the top sources of brain-boosting molecules like polyphenol to fiber. Consuming certain polyphenols and more fiber have been associated with lower risk for developing dementia, better cognition and lower risk for certain mental health issues. Both nutrients help beneficially modulate the gut microbiome which is believed to be key to protecting brain health. A vegan diet is also proposed to help decrease systemic inflammation, a key switch for brain protection.

Cons: Compared to an omnivorous diet, a vegan diet is lower in key brain-active nutrients like the omega-3 fatty acids EPA and DHA, vitamin D as well as B12 and others. There is some concern that a more exclusive consumption of plant-based foods could lead to nutrient absorption issues due to the present of “antinutrients” like phytates, lectins, oxalates, and tannins (although this concern is often likely to be overstated). Finally, many “vegan” foods are ultra-processed junk that are rich in added sugar and other unhealthy ingredients for the brain.

2.    Ketogenic (Keto) Diet

The keto diet is characterized by low consumption of carbohydrates (usually 5-10% of daily calories). Its name stems from the idea that a low carbohydrate diet promotes production of “ketone bodies” which can be used by various organs as an alternate fuel source to glucose. The keto diet has been used medicinally for the treatment of epilepsy since the 1920s. More recently, it’s gained popularity as a diet for weight loss, treatment of metabolic dysfunction and as a potential strategy for dementia prevention and treatment, as well as general brain health promotion.

Pros: A keto diet has already been proven to beneficially affect the brain in adults and children with epilepsy in terms of reducing seizure number. In addition, it’s perhaps the best tool available to reverse and decrease medication dependence in type 2 diabetes, as indicated by recent research. Mechanistically, there are indications that increasing ketones in the bloodstream (a result of a strict ketogenic diet) may have value in brain health, although this has yet to be borne out in consistent human data. Other, albeit limited data suggest benefit in Alzheimer’s Disease. Many who adopt a keto diet will simultaneously decrease consumption of unhealthy processed foods and begin paying more attention to their dietary quality. Lastly, a ketogenic diet may help decrease inflammation, especially in those who are obese.

Cons: Because of its low carb makeup, the keto diet and its variants tend to be lower in fiber. This means higher risk for constipation, along with all the other concerns tethered to a lower fiber intake. Certain people may experience negative effects to their cholesterol panel as a result of following the ketogenic diet, especially those who tend to have more trouble with saturated fat. To this end, a ketogenic diet that prioritizes more unsaturated fat (e.g., olive oil instead of butter) may help mitigate some downside risk.

3.    Carnivore diet

A “carnivore” diet emphasizes the exact opposite of veganism, with a focus on consuming animal-based products as much as possible. Meat, poultry, seafood, eggs and dairy are mainstays. The carnivore diet is a form of a ketogenic (keto) diet due to its low carbohydrate intake, and has been heavily popularized by health influencers over the last five years.

Pros: For many, a decision to consume a carnivore diet is also a decision to decrease consumption of ultra-processed foods (UPFs) and added sugar. As the correlation between UPFs and added sugar and brain issues continues to be demonstrated in the medical literature, there’s certainly a benefit to this aspect of the carnivore diet. As in other instances of keto, those with preexisting metabolic dysfunction may benefit from the decreased consumption of refined carbohydrates, and given the strong links between metabolic issues and brain health problems, this should be considered as a potential value.

Cons: Compared to the other diets described there’s a relative dearth of research supporting the health benefits or risks of the carnivore diet in humans. Two of the biggest liabilities, however, concern the restrictive nature of the diet and the high consumption of animal fat and protein. First, by virtue of excluding plant foods, the carnivore diet is low in fiber and polyphenols that appear to be brain protective and support a healthier gut-brain connection. Diets rich in animal products, especially red meat, are also much higher in saturated fat. The debate over the nuances of saturated fat is still ongoing. However, the research to date indicates that compared to polyunsaturated fats found in fatty fish and whole plant foods like nuts, seeds, avocados and especially olive oil, saturated fats appear inferior for brain health. Lastly, as a relatively extreme diet, sustainability and nutrient deficiency concerns are significant considerations as well.

4.    The Mediterranean diet

The Mediterranean diet variability defined, but at its core is an emphasis on minimally processed food rich in healthy fats, proteins, fiber and plants, and minerals like vitamin D, Vitamin C, and vitamin E. In practice, this means more vegetables, fruits, fish, olive oil, as well as some whole grains and poultry, and an allowance for a bit of wine. In many ways, the Mediterranean diet and its variants (e.g., the MIND (Mediterranean-DASH Intervention for Neurodegenerative Delay)) diet combine the best of other diets to produce an optimal, sustainable brain health eating plan.

Pros: The Mediterranean diet is currently the best-studied diet as it relates to brain benefits. These extend from mood disorders to Alzheimer’s prevention to better brain metabolism to stroke prevention. This diet is linked to lower inflammation and lower risk for systemic metabolic disease, two of the major drivers of brain health. Additionally, because the Mediterranean diet is less restrictive than other diets, it’s likely more sustainable in the long run. Simply put, there is no diet with better evidence for brain health.

Cons: Because the Mediterranean diet is less explicitly defined, it can be misinterpreted to the detriment of brain health. For example, the diet usually allows for a bit of wine. This is very different from justifying consumption of multiple sweetened mixed alcohol drinks in an evening under the pretense of promoting health. The Mediterranean diet can also be seen as expensive (for example, premium olive oil can be quite pricey).

Conclusions:

When it comes to brain health, the Mediterranean diet is the best option for most people. A lower-carbohydrate option like a ketogenic diet may make sense for those needing to acutely improve metabolic function but should be approached cautiously because of issues with long-term adherence and potential loss of key nutrients. A vegan diet, when consumed in the context of a whole-food, minimally processed diet, can be a good option for brain health, but will likely benefit from lab monitoring and supplementation of nutrient insufficiencies (e.g., omega-3 fats and vitamin B12). A carnivore diet may provide benefits to certain subsets of the population but is unlikely to represent an optimal long-term option for brain health for most people.

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