Can eating certain nuts or berries reduce your risk of Alzheimer’s disease? And why do some researchers tout fatty fish and olive oil as preventing cognitive decline?

More than 6 million Americans live with Alzheimer’s disease and the toll is expected to be 13 million by 2050. The Alzheimer’s Association estimates that 1 in 3 seniors will die with Alzheimer’s or a different form of dementia. And it says that COVID-19 greatly contributed to an increase in cases in 2020. The impact of Alzheimer’s ripples out to family and others, as well. The association says there are more than 11 million Americans providing unpaid care to people with some form of dementia.

Since there’s no known cure, efforts focus on prevention.

Nutrition has increasingly been studied as a way to reduce forms of dementia, of which Alzheimer’s is the most common. And the list of helpful foods is fairly long.

A New York Times article points out research showing that folks who have heart disease, high blood pressure, obesity or diabetes are more likely than others to experience age-related cognitive decline. Those risks can be made worse by poor diet and exercise, Dr. Uma Naidoo, the director of nutritional and metabolic psychiatry at Massachusetts General Hospital and the author of “This Is Your Brain on Food,” told the Times’ Amelia Nierenberg.

It makes sense that eating well and exercising could be protective.

Studies show that the Mediterranean diet and the MIND diet — which are similar in their emphasis on fresh produce, seeds, nuts, fish, whole grain foods and olive oil — are seen in studies as offering protection against cognitive decline,

Walnuts protect against oxidative stress and inflammation, suggesting they could reduce the risk or progression of some brain disorders. A study in the journal Nutrients concludes that walnuts can help maintain brain functions and reduce the risk of developing, or at least delay the onset and progression of, dementia.

Rutgers University promotes eating berries as a way to improve brain function. “Berries improve the memory,” wrote Karen Ensle, a Rutgers health sciences educator. “A study conducted with young and old adult participants who ate blueberries showed an increase of blood flow to key areas of the brain, improvements in memory and attention to required tasks. Other tests with seniors eating strawberries and blueberries for several months showed improved memory as compared to those in a placebo group.”

Studies suggest a compound found in pomegranates that reduces inflammation in cases of rheumatoid arthritis and Parkinson’s disease could also reduce inflammation in the brain and help fight Alzheimer’s, according to Alzheimers.net. Researchers believe the pomegranate compound could reduce inflammation in brain cells that are called microglia. When they are inflamed, they destroy other brain cells, which makes symptoms worse for those with Alzheimer's. Over the years, Alzheimer’s experts have told the Deseret News about the brain-health benefits of pomegranate juice.

Christopher Ochner, Ph.D., is so convinced that food matters in preventing dementia that he co-wrote a book called “The Alzheimer’s Diet.” He has some dos and don’ts:

  • Avoid saturated and trans fats; eat unsaturated fats in moderation.
  • Eat foods known for their antioxidants, including beans, berries, kale, mushrooms, seeds, and fatty fish like wild salmon.
  • Select low-fat or no-fat dairy products

Other experts suggest that eating brightly colored fruits and vegetables, lots of leafy vegetables, fat fish at least a couple of times a week and reducing intake of sugary sweets, red meat and high-fat dairy products provide a good framework for brain health and health in general.

But as the New York Times article notes, “dietary supplements may have little effect.” Experts told the Times there’s “little to no evidence that dietary supplements — including fatty acids, vitamin B or vitamin E — will reduce cognitive decline or dementia.”