Can a vegan diet have a negative impact on your mental health?

Can a vegan diet have a negative impact on your mental health?

If done improperly, yes!

Reduced meat diets may be somewhat on trend, but the practice is actually pretty old. There are several cultures that eat plant based diets – India being the most well-known with 40% of the population being vegetarian.  Veganism takes things to another level by eliminating all animal products from the diet.

While no culture eats a strictly vegan diet, there are certainly benefits to giving up meat and animal products.  Animal fats are known to raise cholesterol and have been linked to heart disease, high blood pressure and even certain cancers, so better heart health and lower risk of obesity, cancer and other diseases certainly top the list. However, given that certain nutrients are only available in animal products, if done improperly, a vegan diet can result in nutritional deficiencies that can have a negative impact on one’s mental health. (It is important to note, however, that a vegan diet does not cause mental illness as there can be other factors at play. For instance, the decision to go vegan can actually be a consequence of a mental disorder such as hypochondria.)

Replacing key nutrients

Nutrients linked to mental health that are available solely in animal products are naturally lacking in a strictly plant based diet so you must substitute them in order to remain healthy. These are vitamin B-12, folate, Omega-3 fatty acids and amino acids. Deficiencies in these nutrients have been linked to depression, poor mood regulation, poor metabolism, low energy, as well as memory and attention span difficulties.

Vitamin B-12

Anxiety, depression and mood disorders can be caused by numerous factors (stress, hormones) but B-12 is responsible for regulating mood controlling chemicals like serotonin. Insufficient B-12 reduces the production of these chemicals, which can lead to a mood disorder. Low B-12 can also cause severe forgetfulness and confusion. To ensure optimum levels, vegans need to consume B-12-fortified plant foods, such as fortified soy, seaweed, cereals and nutritional yeast.


There are several metabolic processes in the body that are dependent on folate. Moreover, depressive symptoms are a common symptom of folate deficiency, with depressed patients having folate levels that are on average 25% lower than healthy patients. Sources of folate include dark leafy greens, asparagus, citrus and avocado.

Omega-3 fatty acids

Your body needs omega-3 fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) for normal brain function. Found in fish oil, their job is to maintain cell membrane health and facilitate communication between brain cells. The absence of omega-3 fatty acids leads to a decrease in DHA in the brain, which can result in learning and memory deficits. While you cannot get EPA directly from a vegan diet, the body can actually make EPA and DHA out of ALA (alpha-linoleic acid) which can be found in ground flaxseed, walnuts, canola oil, soy products and hemp beverages.

Amino acids

Protein is made up of amino acids, as are many of the neurotransmitters in the brain. Your protein intake can have a significant impact on your brain functioning and mental health. For instance, the neurotransmitter dopamine is made from the amino acid tyrosine and serotonin is made from the amino acid known as tryptophan. A shortage in either of these amino acids can result in low mood and aggression. Proteins and amino acids are best found in meats and dairy products but vegans can substitute with plant proteins such as beans, peas and grains.

Don’t forget your calories

Following a strictly plant based diet can result in a significant reduction in calories. You may even drop a few pounds. But if that reduction in calories leads to a reduction in key nutrients and carbohydrates, you may find yourself feeling a little “hangry” (i.e., irritable as a result of hunger) during the day. Be sure to supplement your calories adequately.

It works if you do it right

While a well-balanced vegan diet does not cause mental illness per se, nutritional deficiencies can give rise to mental health problems. One great thing about a well-balanced vegan diet is that it is full of “superfoods” like berries and nuts that are known to be beneficial for mental functioning. But the operative word here is “well-balanced.” Eliminating animal products from your diet and replacing them with junk food and other low nutrient choices will undoubtedly lead to deficiencies that will have a negative impact on your mental and emotional state. Do your homework and make the right choices.



McGill Centre for the Convergence of Health and Economics (MCCHE)

Desautels Faculty of Management

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