Fish, leafy greens and nuts help prevent dementia, research says

Nuts benefit cognitive function. Blueberries can strengthen memory. Fish oil supplements may reduce the risk of Alzheimer’s.

You may have seen these encouraging phrases about “foods that boost the brain” sprinkled throughout health articles and social media feeds. But can certain foods or diets actually prevent or delay dementia?

Experts say it’s not easy to conduct studies on nutrition, but a persuasive and ever-growing body of research suggests that certain foods and eating plans may actually have real benefits for the brains of older people. We spoke with more than 20 scientists and examined research to come up with a clearer view of the links between diet and dementia.

Four Pillars of a “Brain Boost” Diet

Scientists are still unaware of the causes of Alzheimer’s disease, the most common form of dementia. And there is currently no drug that can reverse the disease, said Dr. Uma Naidoo, director of nutritional and metabolic psychiatry at Massachusetts General Hospital in the United States and author of “This Is Your Brain on Food”.

“But we can modify our diet,” she said.

Research reveals that people who have certain conditions such as heart disease, hypertension, obesity and diabetes are more likely than people without these conditions to experience age-related cognitive decline. And the risk of developing these conditions can be compounded by a poor diet and lack of exercise. For Naidoo, this suggests that there are things we can do to reduce our chances of developing dementia.

Scientific studies show that two diets in particular, the Mediterranean diet and MIND, offer strong protection against cognitive decline. Both encourage the consumption of vegetables, fruits, legumes, nuts, fish, whole grains and olive oil.

A study published in 2017 analyzed the diets and cognitive performance of more than 5,900 older adults in the US. The researchers found that those who adhered the most to the Mediterranean diet or the MIND diet had a 30% to 35% lower risk of cognitive impairment, compared to those who adhered the least.

“Pretty much anything that helps keep arteries healthy will reduce the risk of dementia,” said Dr. Walter Willett, professor of epidemiology and nutrition at the Harvard T.H. Chan School of Public Health. The Doctor. Ronald Petersen, a neurologist and director of the Alzheimer’s Research Center at the Mayo Clinic, agreed: “What’s good for the heart is good for the brain.”

Green leaves

For Naidoo, an important change you can make to your diet is to “consume more plants”. Leafy greens are loaded with nutrients and fiber, and some solid evidence links them to slower age-related cognitive decline.

For example, in a randomized controlled trial conducted in Israel and published this year, researchers took brain scans of more than 200 people who had been divided into three groups, defined by their diets.

They found that after 18 months, people who ate a “green” Mediterranean diet — rich in mankai (a nutrient-dense green plant), green tea and nuts — had the slowest rate of age-related brain atrophy.

They were closely followed by people who consumed a traditional Mediterranean diet. People who followed traditional healthy eating guidelines — less plant-based and allowing more processed and red meat than the other two diets — had a greater decline in brain volume.

These neuroprotective effects were especially pronounced in people over 50 years of age.

Colorful fruits and vegetables

The more colorful the vegetables on your plate, the more the food will benefit your brain, according to several experts.

In a 2021 observational study, researchers monitored more than 77,000 people for about 20 years. They found that people whose diet was rich in flavonoids — natural substances found in colorful fruits and vegetables, chocolate and wine — were much less likely to complain of signs of cognitive aging than people who consumed fewer flavonoids.

The MIND diet specifically points to berries, good sources of fiber and antioxidants, as foods that promote cognitive benefits. A study published in 2012 followed more than 16,000 people aged 70 and over for more than 12 years. It concluded that the cognitive decline of older women who ate the most blueberries and strawberries was delayed by possibly up to 2.5 years.

“I don’t believe there are any miracle foods, but it’s clear that eating fruits and vegetables is really good,” said Dr. Allison Reiss, a member of the Alzheimer’s Foundation of America’s medical, scientific and memory advisory board.

Fishes

Many types of seafood, particularly fatty fish, are good sources of omega-3 fatty acids, which have been associated for years with better brain health and a reduced risk of age-related dementia or cognitive decline.

“Fish is a brain-boosting food,” commented Dr. Mitchel Kling, director of the memory assessment program at the New Jersey Institute for Successful Aging at the Rowman University School of Osteopathic Medicine.

A specific omega-3 fatty acid — docosahexaenoic acid, or DHA — found in fatty cold-water fish like salmon is “the most prevalent brain fat,” said Lisa Mosconi, director of Weill’s Alzheimer’s Prevention Program. Cornell Medicine.

Our bodies cannot produce enough DHA on their own, Mosconi said. “We need to get it from our diet. That’s a strong argument in favor of eating fish.”

According to Willett, two or three servings of fish a week are enough.

Nuts, chestnuts, whole grains, pulses and olive oil

Nuts and seeds have been repeatedly linked to slowing cognitive decline.

In a 2021 review of 22 studies of nut consumption involving nearly 44,000 people, researchers found that people at high risk of cognitive decline tended to do better when they ate more nuts, specifically nuts. But the authors acknowledged inconsistencies between the studies, as well as some inconclusive evidence.

Another study, this one published in 2014, followed between 1995 and 2001 about 16,000 women aged 70 and over. The researchers found that women who said they consumed at least five servings of walnuts a week had better cognitive scores than those who did not have walnuts as part of their regular diet.

Whole grains, in addition to legumes such as lentils and soy, also appear to benefit heart health and cognitive function. In a 2017 study of more than 200 people aged 65 and over in Italy, researchers identified a link between eating three servings of legumes a week and better cognitive performance.

And olive oil, a major component of the Mediterranean and MIND diets, has strong links to healthy cognitive aging. A 2022 study of more than 92,000 American adults found that higher consumption of olive oil is linked to a 29% lower risk of death from neurodegenerative disease, as well as an 8% to 34% lower overall mortality risk compared to 2022. with people who rarely or never consumed olive oil.

Food supplements may have little effect

According to the experts we consulted, there is little or no evidence that dietary supplements — including fatty acid, vitamin B, or vitamin E supplements — can reduce cognitive decline or dementia.

“Supplements are not a substitute for a healthy diet,” said Dr. Mosconi.

For example, a major study of 3,500 older adults concluded that taking omega-3 supplements, often marketed as products that benefit brain health, does not reduce cognitive decline.

For Willett, there’s no need to gorge on supplements like fish oil. Peterson of the Mayo Clinic recalled the following witty saying: “If it comes from a plant, eat it. [fábrica]avoid.”

Translation by Clara Allain