Is there really such a thing as brain food?

It seems not a week goes by that there isn’t a new study suggesting that eating or drinking one thing or another may help protect against neurodegenerative disease. There have been studies suggesting things as varied as beneficial effects of walnuts on cognition and brain health https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071526/ , speculating that salmon and sardines can help prevent Alzheimer’s disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7071526/ , and positing that blueberry supplementation improves memory in older adults https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2850944/ .

So can certain foods really stave off dementia? The first thing to stipulate when looking at any of these studies finding a link, like eating more blueberries leads to a better memory, is that just because there is an association between two things, it does not mean one thing caused the other to happen. These types of observational studies examine associations; they cannot provide evidence of cause and effect. In order to demonstrate cause and effect in humans, the study design must involve a randomized, placebo controlled trial.

So should we just dismiss all of it and head to the nearest fast food outlet for lunch? No, not at all! Here’s what we know for sure: an unhealthy diet leads to an increased risk of heart disease, high blood pressure, obesity, and type 2 diabetes, all of which are risk factors for dementia. Eating a diet focused on lots of fruits and vegetables, whole grains, lean proteins and good fats from things like olive oil is the way to go because it turns out, what’s good for the heart is good for the brain. As Dr. Walter Willet of the Harvard School of Public Health put it, “Pretty much anything that will help keep arteries healthy will reduce the risk of dementia.”

Research shows there are four pillars of the healthy diet for your heart AND your brain.

The first pillar is leafy greens. In one of the longest and largest brain MRI trials ever done, https://pubmed.ncbi.nlm.nih.gov/35021194/ scientists showed that a green Mediterranean diet, consisting of foods rich in polyphenols and low in red and processed meats, slows down age-related brain atrophy. The most dramatic improvement came in people over 50.

The second pillar is colorful fruits and vegetables. Researchers followed the diets of more than 77,000 men and women in the United States for 20 years and published their findings in the journal Neurology last year. https://pubmed.ncbi.nlm.nih.gov/34321362/ They found that those with diets high in flavonoids – natural substances found in colorful fruits and vegetables – were less likely to report signs of cognitive decline.

The third pillar is fish. Omega-3 fatty acids have been associated with reduced risk of age-related dementia. This is all about docosahexaenoic acid, or DHA, a type of Omega-3 fatty acid found in cold water fish like salmon. Our bodies can’t make enough DHA on their own and it must be provided through the diet. Nutritionists believe 2-3 servings per week will provide the maximum benefit.

And, finally, the fourth pillar is nuts, whole grains, legumes and olive oil. A Harvard study, published in January of this year https://pubmed.ncbi.nlm.nih.gov/35027106/ followed 92,000 people from 1990 to 2018. It found that those who consumed olive oil daily reduced their risk of death from neurodegenerative disorders, such as Alzheimer’s and Parkinson’s disease, by 29%. Olive oil is packed with healthy fats, nutrients and antioxidants, so it’s best to skip the mayo, butter, and margarine.

Wouldn’t it be great if we just skip this and take a supplement? Surely there are thousands of them to choose from, many touting benefits. Here’s the fishy truth about fish oil. In one of the largest studies of its kind, researchers at the National Institutes of Health followed 4000 people over 5 years, finding that Omega-3 supplements did not slow cognitive decline in older adults. https://jamanetwork.com/journals/jama/fullarticle/2429713 With so much confusing dietary information, here’s a bottom line rule that will never fail you, courtesy of food journalist Michael Pollan: “If it comes from a plant, eat it. If it's made in a plant, don’t.”