A healthy diet may lower dementia risk — even if you start late

By Janet Lee – Washington Post

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Doing puzzles, playing memory-boosting games, taking classes and reading are activities that we often turn to for help keeping our brains sharp. But research is showing that what you eat, how often you exercise and the type of exercise you do can help lower your risk of dementia to a greater extent than previously thought.

Although more studies are needed, “there’s a lot of data that suggests exercise and diet are good for the brain and can prevent or help slow down” cognitive changes, says Jeffrey Burns, co-director of the University of Kansas Alzheimer’s Disease Research Center in Fairway.

And living a healthy lifestyle can produce brain benefits no matter what your age.

The big diet picture

If you’re already eating in a way that protects your heart — plenty of whole grains, vegetables, and fruit, and little saturated fat, sodium and ultra-processed “junk” foods — there’s good news: You’re also protecting your brain. A healthy cardiovascular system keeps blood vessels open, allowing good blood flow to the brain and reducing the risk of high blood pressure, stroke and dementia.

Research suggests that two specific dietary approaches — the Mediterranean diet and the MIND diet (the Mediterranean-DASH Intervention for Neurodegenerative Delay, essentially a combo of two heart-healthy eating plans) — may help stave off cognitive decline. Both diets rely on eating mostly plant foods (fruits, vegetables, whole grains, beans, nuts), olive oil, fish and poultry. The main difference between the two is that the MIND diet emphasizes specific fruits and vegetables, such as berries and leafy greens.

Studies show that people who most closely follow either diet have a reduced risk of dementia compared with those who don’t. For example, people eating the Mediterranean way had a 23 percent lower risk of dementia in a nine-year study of more than 60,000 men and women published this year in BMC Medicine.

The original MIND diet research, published in 2015 by researchers at Rush University in Chicago and still ongoing, found that older adults who adhered most closely to the diet had a 53 percent lower risk of developing Alzheimer’s disease. Even those who followed the MIND diet moderately well saw a 35 percent reduced risk.

Brain-boosting foods

“Simply focusing on one food won’t magically improve cognitive functioning,” says Puja Agarwal, an assistant professor at the Rush Alzheimer’s Disease Center. “We found that it’s a combination of foods that are associated more with overall brain health.” Still, within the context of a healthy diet, including the following on your plate regularly may give your brain some extra protection.

Healthy fats: The mono- and polyunsaturated fats found in foods such as avocados, olives, nuts, seeds and olive oil protect against heart disease and stroke, both risk factors for Alzheimer’s disease. Omega-3 fatty acids, a type of polyunsaturated fat found in seafood, as well as walnuts and chia and flax seeds, may slow brain aging.

“Some studies show consuming omega-3 fatty acids [in food] may help lower levels of beta-amyloid, a protein that forms damaging clumps in the brains of people with Alzheimer’s disease,” says Lauren J. Gleason, an assistant professor of medicine at the University of Chicago Medicine.

Berries: All berries contain flavonoids, which are powerful antioxidant compounds. A large 2021 study, published in Neurology, found that people who had the highest intake of flavonoids were 19 percent less likely to self-report a decline in cognitive function than those who ate fewer flavonoid-rich foods. Berries in particular appear to protect brain cells from damaging oxidative stress and help boost memory, Gleason says. (Tea and dark chocolate also have flavonoids.)

Beans: Legumes are rich in fiber. Per (cooked) cup, lentils have 16 grams, chickpeas about 13 grams and kidney beans 11 grams. (The daily value is 28 grams.) A 2022 study of older people in the American Journal of Medicine found that as fiber intake increased, so did scores on a brain function test that measured information processing, attention and memory. (Fruits, vegetables and whole grains are other good sources of fiber.) “Getting adequate fiber also helps you maintain a healthy weight, balances blood sugar levels, and improves heart health, all of which are linked with cognitive health,” Gleason says.

Fiber may help the brain in an unusual way. It supports a healthy microbiome, the collection of good bacteria that lives in your digestive system. Having enough of these good bacteria is crucial because their activity creates short-chain fatty acids that communicate with the rest of the body, including the brain. Some data shows that people with Alzheimer’s disease have a different microbiome makeup than those who don’t have it, Burns says. Researchers are looking into whether the balance of bacteria in the gut is a cause or a result of the disease. If it’s a cause, then changing your microbiome may be beneficial.

Eggs: The yolks are rich in choline, a nutrient that’s important for memory and other brain functions. In a 2019 study involving almost 500 men, published in the American Journal of Clinical Nutrition, every 50 milligram intake per day of a type of choline called phosphatidylcholine was linked to a 10 percent decrease in dementia risk. Eggs were the main source of phosphatidylcholine in the men’s diet. A large egg has 168 mg of choline, about 70 percent of which is phosphatidylcholine.

Foods that are bad for the brain

You also want to be sure to limit foods that have been shown to hinder cognitive health. One way to do this is to cut back on highly processed foods. These are foods that have ingredients such as high-fructose corn syrup, emulsifiers, colors, flavors and preservatives, or are high in added sugars or sodium. Soda, packaged bread and baked goods, sugary cereals, and deli meats are examples.

Getting just 20 percent of calories from highly processed foods was linked to a 28 percent faster rate of cognitive decline compared with eating less. That’s according to an eight-year study of more than 10,000 men and women ages 35 to 74, published in 2023 in JAMA Neurology.

Another study, published in the journal Neurology, found that people 55 and older who ate a highly processed diet were about 25 percent more likely to develop dementia than those who ate little of these foods.

But there was also good news: Those who reduced their intake of highly processed foods by 10 percent during the 10-year study were 19 percent less likely to get dementia.

How exercise helps

Regular physical activity may improve brain health in numerous ways, not least of which is reducing risk factors for dementia, such as diabetes and heart disease. A 2023 analysis of 21 studies, published in the International Journal of Environmental Research and Public Health, concluded that exercise (both aerobic and strength training) improved cognitive function in older adults regardless of their current cognitive status. Researchers speculate that physical activity helps by encouraging the growth of new neurons and blood vessels in the brain, fighting inflammation, and improving plasticity, the brain’s ability to change and adapt.

The World Health Organization recommends getting 150 to 300 minutes of aerobic exercise — such as walking, cycling or swimming — a week and two or more strength-training sessions.

“Activities that involve learning a specific sequence of movement may be particularly beneficial in slowing progression to dementia in someone who has mild cognitive impairment,” Gleason says. A small study of older adults with this condition, published in 2020 in the Journal of Alzheimer’s Disease, found that those who did choreographed aerobic dances (an hour twice weekly for 12 weeks) improved verbal recognition memory more than those who did physical therapy exercises. Activities such as dancing and tai chi also challenge balance, a skill that declines with aging and the onset of dementia.

Copyright 2023, Consumer Reports Inc.

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This article was originally published at Washington Post

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