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Healthy dietary patterns, including the MIND and Mediterranean diets, have been associated with a slower rate of cognitive decline and protection against Alzheimer’s disease.

“MIND” is short for Mediterranean-DASH Diet Intervention for Neurodegenerative Delay. The eating pattern includes elements of the Mediterranean and blood-pressure-lowering DASH diet, as well as specific foods and nutrients linked to optimal brain function.

Now, a study from Rush University Medical Center in Chicago suggests that both dietary patterns can prevent the buildup of beta-amyloid plaques in the brain, a hallmark sign of Alzheimer’s disease.

The latest research

The study, published March 8 online in the journal Neurology, involved 581 people taking part in the Rush Memory and Aging Project, a continuing study of older adults initiated in 1997. Participants were dementia-free when enrolled into the study.

Participants in the current analysis, average age of 84 at the start of the study, had agreed to donate their brains at death to advance dementia research.

They underwent annual diet assessments during the years of follow-up before death. The researchers then computed scores to determine how closely their diets matched the MIND and Mediterranean diets.

The MIND diet score was calculated by assessing intake of brain-healthy food groups (e.g., leafy greens, berries, nuts, fish, olive oil) and brain-unhealthy food groups (e.g., red meat, butter, cheese, sweets, fried/fast food).

The Mediterranean diet score was determined by measuring consumption of 11 dietary components, including whole grains, fruits, vegetables, beans/lentils, olive oil, fish and potatoes.

A higher score indicated better adherence to these dietary patterns.

Brain autopsies were performed to evaluate amounts of beta-amyloid plaques and tau tangles, proteins that, when they accumulate, can disrupt brain cell function and slow a person’s ability to think and remember.

The findings

The participants died an average of seven years after the start of the study.

Overall, those with the highest MIND diet or Mediterranean diet scores had a lower buildup of beta-amyloid plaque and tau tangles in their brain; they were 40-per-cent less likely to be diagnosed with Alzheimer’s disease at autopsy.

The findings remained unchanged after accounting for other risk factors, including age at death, sex, education, daily calorie intake and whether participants had a gene linked to Alzheimer’s disease.

According to study author Puja Agarwal, assistant professor at the Rush University Medical Center, people who had the highest MIND diet scores had beta-amyloid and tau tangle amounts similar to being 12 years younger compared to participants who scored the lowest. Closely adhering to the Mediterranean diet was associated with plaque and tangles amounts corresponding to being 18 years younger.

The results also showed that having a MIND diet score one point higher – indicating improvement in just one food group such as eating more berries or eating less red meat – corresponded to a typical plaque buildup of being four years younger.

When the researchers looked at single diet components, they found that leafy greens – e.g., spinach, kale, Swiss chard, collards, rapini, arugula – provided the most benefit.

The MIND and Mediterranean diets are rich in plant foods which supply nutrients and phytochemicals that are crucial for brain functioning and also exert antioxidant and anti-inflammatory properties thought to protect brain cells.

Leafy greens are excellent sources of vitamin K, folate, beta-carotene and lutein, nutrients believed to help preserve brain functioning.

This study was observational and, as such, doesn’t definitively prove that following these dietary patterns delays the onset of Alzheimer’s disease.

Still, these new findings add to mounting evidence that making simple diet changes, such as adding leafy greens to your daily diet, can help protect your brain as you age.

A closer look at the MIND diet

Introduced in 2015 by researchers at Rush University Medical Center, the MIND diet provides advice for including nine specific brain-healthy food groups in your diet.

Leafy green vegetables are recommended daily (one half to one cup); as are other vegetables (one half-cup).

Three daily servings of whole grains should also be included; a serving is one half-cup of cooked grains or whole grain pasta or one slice of whole grain bread. Two tablespoons of extra virgin olive oil are recommended each day.

Food groups to eat weekly are berries (five half-cup servings), nuts (five ounces), beans, lentils and/or soy (three half-cup servings), fish (one three- to five-ounce serving) and poultry (two three- to five-ounce servings).

Five brain-unhealthy food groups to limit include red and processed meats (no more than three servings/week), butter and stick margarine (no more than a teaspoon daily), whole fat cheese (less than an ounce a week), pastries and sweets (no more than four servings a week) and fried/fast food (no more than one meal a week).

The good news: You don’t have to follow the plan perfectly. Even following the MIND diet moderately well has been tied to a lower risk of Alzheimer’s disease.

Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD

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