What you eat could be key to improving your mental health, scientists say

The Dose24:21What does my mental health have to do with the health of my gut?

Maintaining good mental health can sometimes feel challenging, but it turns out one piece of the puzzle is deceptively simple — what’s on your plate. 

“Nutrition and mental health is this connection that people have actually been writing about for centuries,” Dr. Mary Scourboutakos, who goes by Dr. Sco., told Dr. Brian Goldman, host of CBC’s The Dose

“But only now are we getting this evidence to accumulate to support this connection,” said Scourboutakos, a family doctor who also has a PhD in nutrition.

Research shows that the types of microbes found in our gut, or gastrointestinal tract, could have a direct impact on our mood

And experts say that changing your diet is one of the best ways to influence those microbes, which could in turn help people suffering from mental illness. 

“It’s a question of augmenting a tool that we’re already using, which is very encouraging,” said Scourboutakos. 

In one Canadian study, researchers were able to show that when 10- and 11-year-olds met recommendations for diet, as well as sleep, physical activity and screen time, they were less likely to need mental health interventions as adolescents. 

“That’s very, very powerful,” said Dr. Bonnie Kaplan, a psychologist and professor emeritus at the University of Calgary’s Cumming School of Medicine. 

“The children who are eating real food have fewer reports of anxiety and depression,” said Kaplan. 

The study, which used self-reported data, found that a nutrient-rich diet was among other lifestyle recommendations that accounted for fewer mental health visits.

Conversely, a study published this month by JAMA Network Open found that participants who had diets high in ultra-processed foods had the highest risk of depression. 

How does our gut talk to our brain? 

Our gut — or gastrointestinal system — is connected to the brain, which is how diet can directly affect mood. 

Inside the gut is our microbiome, made up of trillions of swirling bacteria — some good and some bad.  

“They help us digest our food. They help inform and strengthen the lining of the gut wall. They outcompete bad bacteria. And they’re basically like the thermostat that controls the level of inflammation in our body,” said Scourboutakos. 

Every time we eat, we’re feeding those bacteria, she said, both the good and the bad. 

When we eat foods that are rich in dietary fibre, for example, we’re feeding the good bacteria. 

A 3D illustration of enterobacter bacteria, part of normal microbiome of the intestines. The healthy microbes in our bodies strengthen the lining of the gut wall and outcompete bad bacteria. (Kateryna Kon/Shutterstock)

“They share their excitement about this by sending signals to your immune cells that live right next door. Those immune cells then respond and release their own signals that travel throughout the bloodstream and eventually reach our brain, where they can then influence our mood and our anxiety levels,” Scourboutakos said. 

Another way to think of the process is to compare it to taking oral medication, said Carolina Tropini, an assistant professor in the Department of Microbiology and Immunology at the University of British Columbia. 

The microbes in our gut make compounds that enter our bloodstream, said Tropini, “the same way that when you take a pill by mouth, it makes it through your blood system.” 

Those compounds from our gut microbes are small enough to cross the blood-brain barrier and enter the brain, just like medications, she said. 

What foods help the brain? 

Studies have shown that following what’s known as the Mediterranean diet can prevent and reduce symptoms of depression and anxiety. 

This type of diet looks a lot like Canada’s Food Guide, said Scourboutakos — eating vegetables and fruits, whole grains, beans, nuts, and fish and small amounts of dairy, meat, and eggs. 

Experts say one of the common denominators of this type of diet is fibre, the parts of plant foods that the body can’t absorb — but are nonetheless essential to our health.   

“What our grandmas told us still stands. Eat your fibre, is basically the bottom line,” said Tropini. 

Scourboutakos. advises choosing these specific foods more often to boost the fibre in your diet: 

  • Broccoli, cabbage, cauliflower, brussels sprouts, green peas, artichokes, pumpkin
  • Berries, apples, pears, avocados, mangos
  • Beans, legumes, lentils, chickpeas
  • Nuts, especially almonds and pistachios 
  • Whole oats, barley, bulgur, corn
  • Certain breakfast cereals (read the nutrition label to check) 

How microbiomes evolve 

Although changing our diet can have a big impact on our microbiome, some of our bacteria are established from birth — literally. 

“Babies that are born by C-section start with a very different microbiome than babies who are born vaginally,” said Scourboutakos. That’s because babies encounter a greater variety of beneficial microbes on their way through the birth canal than they do through a surgical birth. 

Whether a baby is fed breast milk or formula also fundamentally influences the microbiome. 

One of the benefits of breast milk, said Tropini, is the components in the milk that a baby can’t digest that go straight to the microbiome. 

“We really have evolved to be in contact with these microbes, and making sure that they stick with us from the get-go seems to be really, really critical for our health.”

A woman stands in front of a market stall loaded with fresh vegetables.
Eating a variety of vegetables and fruits in as close to their natural state as possible, and reducing highly processed foods, is correlated with better mental health. (CBC/Radio-Canada)

Not a magical cure 

Mental illness is often caused by a complex range of factors and changing your diet won’t necessarily be a magical cure, experts say. 

“There are a lot of causes of mental disorders and you can’t go back and remove the history of abuse without intensive psychotherapy,” said Kaplan. 

But diet is a relatively easy way to make changes and see how you feel, said Scourboutakos. 

“Even for those who are already on antidepressants, the evidence shows it can have additional benefits above and beyond the medication,” she said. 

The challenge is to translate the research into better understanding and policy.

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“How do we motivate people to eat in this manner? How do we make it feasible for them? How do we make it interesting for them?” said Scourboutakos. 

One way could be promoting the cost-saving benefits.

A study in Australia showed that moving to a modified Mediterranean diet centred on eating whole foods as opposed to processed ones saves money, said Kaplan. 

Food costs have risen exponentially recently, and it takes time and skill to transform whole foods into delicious meals. 

But if you’re struggling with your mental health, it may be worth that effort. 

“It’s one of the easiest ways in which we can change things in our body,” said Tropini.

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