Researchers link vegetarian diets and depression


In the last five years, I’ve significantly reduced the amount of meat I make. The vast majority of meals I cook at home are vegan or vegetarian and I like to try vegetarian dishes when I am eating out. But I haven’t given meat up completely - because I'm not convinced that going vegan is the best option. The science is far from conclusive. 

I'm a big fan of Dr. Drew Ramsey and his work in nutritional psychiatry. Dr. Ramsey is one of psychiatry’s leading proponents of using nutritional interventions. His New York clinic offers evidence based nutritional interventions and integrative psychiatric treatments to treat depression, anxiety, and emotional wellness concerns.

Dr. Ramsey was a vegetarian for around a decade but began eating meat again after he started researching nutrition and it’s impact on our mental and physical health. There are certain nutrients that we need for our brains and nervous systems to operate optimally and some of those nutrients are hard, or even impossible to get when eating a vegetarian diet (I know I am going to catch some heat from veggies on this one but I am talking about a vegetarian/vegan diet without supplementation).

I recently came across a research paper titled ‘Vegetarian diets and depressive symptoms among men’. The study involved more than 9600 men in Australia who provided self-reported data. Vegetarian diets are associated with decreased risk of cardiovascular death, obesity and diabetes, but little is known about how it impacts mental health - so the study aimed to explore a potential connection. 

Results showed that vegetarians (a category that they included vegans in) had higher depression scores on average than non-vegetarians and a greater risk for symptoms of depression. These results are similar to other studies that have been done:

  • Vegetarian women had a 22% rate of elevated depression symptoms, compared to 15% for non-vegetarians
  • A study with Australian men showed that lower red meat consumption was associated with nearly double the risk for major depressive and anxiety disorders.
  • In a study with Norweigan students, nearly twice as many men and one third more women with low meat consumption reported having been depressed


What's missing in a vegetarian diet?


Note that not all ‘vegetarian’ diets are the same. Some vegetarian diets include fish (Pesco-Vegetarian), eggs and dairy (Lacto-ovo Vegetarian), or include no animal products at all (vegan). In a small study of Seventh Day Adventist adults found no increased risk of depression or anxiety among vegetarians who excluded fish. A diet that includes fish, eggs, or dairy will provide some of nutrients essential for brain functioning that a vegan diet will not. 

Omega 3 fatty acids, specifically docosahexaenoic acid (DHA), are found in fish, oysters, mussels, fish oils, and specialty egg and dairy products. DHA is found in high levels in the spaces between nerve cells and is essential for nerves to function properly. Several studies have shown that omega-3 fats are effective in treating significant depressive symptoms.

Vitamin B12 can be made by bacteria (often not in sufficient amounts) and is found mainly in meat, egg, and dairy products but there is no significant plant source. B12 is essential for maintenance of a healthy nervous system, and since the brain is essentially just a collection of neurons constantly communicating with each other, it’s important for a healthy brain and thus, mood. The study also notes that deficits in zinc and iron may also play a role as a risk factor for depression for vegetarians.  

So, vegetarians are known to have lower intakes of omega-3 fatty acids, vitamin B12, and folate - all essential for brain health. But in addition to potential diet deficiencies, vegetarians tend to eat more nuts high in omega-6 fatty acids, which may be linked to higher rates of depression. People who eat a vegetarian diet also have high levels of phytoestrogens and metabolites of pesticides in their blood, which can contribute to brain functioning.


So what gives?

There are many, many benefits to adopting a plant-based diet. It’s better for the environment (in fact, going vegan reduces your carbon footprint by 0.8 tonnes per year — a bigger difference than replacing your gasoline-powered car with a hybrid), it could be considered more ethical than a diet that includes animals raised in feedlots or ‘factory farms’, and it can be cheaper and more convenient (no having to use a separate cutting board or thawing meat beforehand). As mentioned earlier, a vegetarian diet also promotes a healthy heart and cardiovascular system and can reduce your risk for obesity and diabetes.

I think that there is a middle ground here. According to the research, the best approach to a diet that supports physical and mental health is to:

  • Eat mostly plants – focus on eating a variety of vegetables (including leafy greens and a variety of colourful veggies), fruit, nuts and seeds, whole grains
  • Eat seafood and/or fish 2 – 3 times per week
  • Include red meat or poultry occasionally (opt for grass-fed, organic meat if it’s an option)
  • Include fermented foods in your diet to help maintain healthy gut bacteria. Fermented foods include yoghurt, sauerkraut, kim chi, kombucha, kefir
  • Limit or avoid processed and fast food

If you do decide to eat meat, I strongly urge you to be intentional about where your meat and meat products come from. If it’s an option for you, seek farmers at Farmer’s Markets or who sell at local grocery stores that you can trust. Animals that are grass-fed have healthier types and levels of fat in their meat, and by choosing organic, free-range meat, you are decreasing your exposure to chemicals, pesticides and herbicides, and hormones. 

As a last note, I would like to remind you that research should always be taken with a grain of salt. There are limitations to this study. The study was conducted with only men. There is also the possibility that the increased risk for depression found is not related to any dietary differences, but
is due to natural differences in the personality or psychology of vegetarians and vegans. 

I am not saying that a vegetarian diet is bad, or that an omnivorous diet is good. I think that a vegetarian diet can be healthy if done properly . I present this study simply as food for thought.