Brain health: food’s next frontier

Canada’s Food Guide is the federal government’s go-to resource on what Canadians should and should not eat.

Health Canada spends years researching and consulting with experts before it publishes an update of the guide. That’s because, as noted on the food guide website, it can help Canadians choose foods that improve health, meet nutritional needs and help them reduce the risk of cancer and heart disease.

In the future, it might be a good idea for the next food guide to pay more attention to how food influences diseases of the brain, like Alzheimer’s and dementia.

Richard Bazinet, associate professor in nutritional sciences at the University of Toronto, recently conducted a word search in the 2019 food guide.

The words “heart” and “cardio” appeared 124 times, but a search of “brain” and “neuro” produced zero results.

“The next big wave of things we need to treat are the brain disorders…. The brain is the next cardio-vascular disease, the next cancer,” said Bazinet.

“A lot of people are (now) interested in looking at nutrition (for the) prevention of neurological disorders.”

Bazinet is a Canada research chair in something called brain lipid metabolism. He studies dietary fats, like vegetable oil and fish oil, and how those foods may affect brain functioning.

He shared some of his research and findings during a presentation at Canola Week, a Canola Council of Canada virtual event held in early December.

Bazinet and other researchers are interested in dietary fats, likely because the brain is mostly made of fat.

“Did you know up to 70 percent of our brain is made of fat?” says Liz Weinandy, a registered dietician with Ohio State University. “Fat is very important for proper brain function, but it needs to be the right kind of fat. We need to get enough omega-3 fatty acids because these are the essential building blocks of our brain and they’re important for learning and memory.”

Omega-3 fatty acids can be found in flaxseed oil, canola oil, salmon and tuna. Eating those foods may improve brain health, but the relationship between omega-3 fatty acids and preventing brain diseases isn’t clear.

There is some evidence, but the link isn’t a scientific certainty.

Researchers have studied people who develop brain diseases and those who don’t, then tracked their diets to look for common themes.

“We can see that things like omega-3 consumption are associated with lower risk of getting these brain disorders (like Alzheimer’s),” said Bazinet.

But the problem with such studies is it’s difficult to pinpoint a particular food and then separate it from other factors. Someone who eats a lot of fish and flax may also exercise more than other people. The exercise could be preventing Alzheimer’s, not the flax.

“So, we’re not sure that the relationship is true,” Bazinet said in an interview from his office in Toronto.

There isn’t absolute proof but researchers like Bazinet are making progress on the science of nutrition and brain health.

A few years ago, he learned that there are four grams of DHA (an omega-3 fatty acid) in the average brain. The brain needs omega-3 fatty acids, like DHA, to perform certain functions, such as “regulating mood, sleep, blood flow and inflammation of the brain,” the Canada Research Chair website states.

If a child is deficient in DHA, it could be a cause of certain neurological disorders.

“Several researchers have observed that kids with ADHD have lower levels of omega-3s, including DHA, in their cells and bloodstream,” Scientific American said in 2012.

Of the four grams in an adult’s brain, only four mg of DHA per day are needed to replace what is lost. That isn’t much, but the tricky bit is getting the DHA from the stomach to the brain.

Canadians could eat more fish to get their daily dose of omega-3 DHA because fish oil contains DHA, which is the substance that brains need.

But there are only so many fish in the world. Consuming more fish and fish oil to maintain brain health may not be sustainable for the planet or fish.

That’s where canola and flax come into the picture.

Canola oil and flax oil contain ALA (alpha linoleic acid), which must be converted to DHA in the human body.

The conversion rate is low, yet a portion of the flax or canola oil does become DHA.

“When we see those numbers, the role of Canadian crops… starts to jump out as being a little more plausible. Because four mg isn’t a ton. It’s not a super-high number,” Bazinet said.

There is some evidence that canola oil and flaxseed oil can help with brain health, but Canadians shouldn’t start drinking a litre of canola oil every day.

Scientists first need to answer a few questions.

For one, they don’t fully understand if DHA is needed to protect brain health and what it might be doing in the human brain to ward off diseases like Alzheimer’s.

There have been studies on mice showing that higher omega-3 levels will help control brain inflammation.

“We think brain inflammation is a risk factor for things like Alzheimer’s,” Bazinet said.

“Those studies give us a proof of concept…. (But) extrapolating from the mouse… to a human is a big jump.”

There’s also the question of how much omega-3 is needed at different stages of life.

Does someone in their 50s or 60s need a higher intake of fish oil or canola oil to deliver more DHA to their brain? Does the requirement change with age?

“(We need) a better understanding of those variables… to get the brain the right amount of DHA,” Bazinet said. “Understanding how much the brain uses is a (way)… to get an idea of how much (of a certain food) we need.”

The good news is that foods that lower cholesterol levels and control cardio-vascular disease, like flax oil, may also benefit the brain.

So, flax oil and canola oil may or may not prevent dementia, but there isn’t much to lose by adding them to the diet.

“It’s a fairly low risk public health approach… It fits into our general nutritional (guidelines),” said Bazinet, who is frequently asked to speak about brain health at events like Canola Week.

“We’re seeing a growing interest in these areas (of research)… as people start to realize that the brain can be affected by nutrition.”