You are what you eat is such a common refrain that it has almost lost its punch. But be careful about letting that established wisdom pass you by. From heart disease to diabetes, from obesity to osteoporosis, we know that diet plays a role in the genesis of many diseases. More recently, research has been showing that diet influences mental health issues, including depression, insomnia, and ADHD. What’s more, there’s some preliminary research showing that diet can impact your dementia or Alzheimer’s risk.


The most worrisome diet is the contemporary Western diet, as it has been proven to lead to negative health outcomes. It’s a diet comprised mostly of refined grains, refined sugars, refined vegetable oils, red meat, milk, and alcohol; at the same time it is low on the healthier foods like vegetables, nuts, and seeds. According to an article published in The American Journal of Clinical Nutrition in 2005, more than 72 percent of food consumed in the United States was made up by food in the “Western diet” category. It is a diet borne of industrialization, when food processing seriously altered the “norms” of eating. Newer research out of Leger Marketing, and completed with celebrity chef Ricardo Larrivée, looked at the eating habits of Canadians and found that only one out of every ten people feel like they are reaching their goal of eating a healthy diet. This is even though Canadians are definitely more conscious about healthy eating than before – more than 55 per cent of Canadians buy something organic every week at the grocery store and the purchase of local veggies grown through smaller-scale community-supported agriculture is gaining traction.


Does it really matter if you replace that fast-food joint’s burger and fries or sugary, packaged cereal for fruit, veggies, healthy meats, essentials fats, and the like? It really does – the quality of your diet impacts not only your physical health but also your brain. And here’s why: “Our brains require a huge number of vitamins and minerals every minute that our heart is beating; in other worlds, every minute we’re alive,” says Bonnie Kaplan PhD, Professor Emeritus, Cumming School of Medicine at the University of Calgary. “Approximately a litre of blood perfuses your little two-and-a-half to three pound brain every 60 seconds that your heart is beating. What is it doing? Of course, it’s bringing oxygen and taking away waste products – but it’s also bringing all the vitamins and minerals into your brain that you’ve eaten in the last few hours – and that’s every minute of every day, 24/7.” The vitamins and minerals we take in through food – and for some people, supplementation, if you are not getting enough through food (though always check your symptoms with your family doctor before starting supplementing) – “are used in every metabolic step in our brains,” says Kaplan. Most of us know serotonin, as just one example, which is a hormone and a brain neurotransmitter that makes us feel happy. But what many don’t know is that the majority of serotonin is made through our digestive tract and not directly in the brain. “We don’t eat serotonin. What we eat are the precursors to serotonin,” says Kaplan. It’s not only serotonin: enzymes, vitamins, and minerals are needed at each step of the process “for every chemical in your brain.” When you think about it that way, a picture of how important nutrition is for the brain becomes clearer.


Likewise, the brain is two-thirds fat and our bodies don’t produce the fats we need – “the good fat, the omega 3 fatty acids that are very important for building and maintaining the cell walls of our brain cells,” says Dr. Kaplan. We need to eat these fats. Good food sources of essential fatty acids include seafood, such as sardines and salmon, as well as flax seeds, other nuts and seeds, as just a few examples. “You should never eat a low-fat diet. Every cell in your body is made up of fat. You might want to do a no-bad-fat diet but not a low-fat diet,” says Dr. Eva Selhub, Adjunct Scientist in the Neuroscience Laboratory at the Jean Mayer USDA Human Nutrition Center on Aging At Tufts University, and author of Your Brain on Nature. It has been established in the medical literature that traditional diets, such as those found in Japan (high in fish and low in saturated fats) and the Mediterranean (high in the heart-healthy olive oil, vegetables, legumes), ones that are naturally higher in the good kinds of fat, have been proven to lower the risk of certain diseases, especially cardiovascular disease. Now, interesting research is being published that shows that traditional diets can help protect against brain diseases. Work published in The Journal of Alzheimer’s Disease studied changing dietary trends in Japan ­– where the traditional diet is slowly changing due to an influx of Western foods and an increase in obesity and alcohol consumption – and found that Alzheimer’s rates have “risen rapidly in recent years.”


High carb and high sugar diets are also being established as being worse for your brain. Research out of the Mayo Clinic found that elderly people whose diets “with relatively high caloric intake from carbohydrates and low caloric intake from fat and proteins may increase the risk of (mild cognitive impairment) or dementia,” according to the paper. And research published in The New England Journal of Medicine found a correlation between high glucose levels and getting dementia, whether people had diabetes or not. In fact, the study says that their “data suggest that higher levels of glucose may have deleterious effects on the aging brain.” The Western diet is high in sugar and less-healthy carbs that get converted to sugar more quickly – instead of complex carbohydrates like vegetables or legumes. But it could also come down to having a good balance because the traditional Japanese diet tends to be higher in carbs, too, but they eat a variety of healthier foods – like fish, eggs, meat, soy, and a variety of veggies.


The Western diet has even been recently connected to having a smaller hippocampus, according to research published in the journal BMC Med. The hippocampus, according to the study, “is a brain structure associated with both learning and memory, as well as mood regulation, and is specifically implicated in depression.” This work builds on the growing volume of research that shows a connection between a healthier diet and improving mental health, which is absolutely “a function of the brain,” says Kaplan, something “a lot of people don’t believe. In general when you’re eating, you’re feeding your brain. Your brain needs those nutrients more than any other organ in the body, expect the heart, which comes close in terms of metabolic demand. You’re not going to get optimal nutrient content from processed foods.”


Feeding your brain the best food is crucial at all ages, but as we get older it becomes all the more important because it is more difficult for our bodies to absorb the nutrients we take in, even though at the same time our bodies need better nutrition to perform well, according to the National Institutes of Health in the U.S. Think of it this way: “Your brain is not a Chevy. It’s a Lamborghini,” says Selhub. “It needs to be fuelled with really good, clean, healthy, strong, positive fuel. If you don’t feed it that way it will lose itself. If people want to live as long as we’re living and still have their brain intact they’re going to need to cut out the processed food and the sugar from their diet.” Food for thought indeed.