Older adults who munched, crunched, and sipped the most flavonols—beneficial compounds in fruit, vegetables, tea, and wine—were 48 percent less likely to develop Alzheimer's disease than people who consumed the least, according to a January 2019 report in Neurology. "This observational study does not prove cause and effect, but it adds to the idea that food is very important for brain health," says the study's lead author, Thomas M. Holland, MD, a researcher at Rush University in Chicago.

Dr. Holland and colleagues tracked 921 women and men for three to nine years, using yearly cognitive and memory tests plus in-person medical exams to diagnose dementia likely caused by Alzheimer's. Participants—who had no signs of dementia at the start of the study—filled out annual food questionnaires, which the scientists used to estimate daily flavonol intake. Those who consumed at least 15.3 milligrams of flavonols—the amount in a small leafy green salad, one serving of cooked vegetables, or a half-cup of berries—per day had the lowest risk even after researchers adjusted for exercise levels, education, mentally stimulating activities, and the APOE4 gene, which increases the risk of developing Alzheimer's in late life.

"Flavonols have anti-inflammatory and antioxidant properties," Dr. Holland explains. "Antioxidants help destroy free radicals, which damage cells. Anti-inflammatories reduce inflammation, a natural process that can damage cells if it is overactive or sustained for too long." In animal studies, flavonols boosted memory and learning and decreased Alzheimer-like brain changes.

"The study strengthens the argument for a potentially beneficial role of fruits and vegetables in brain function and provides an additional reason to consume them," says Nikolaos Scarmeas, MD, associate professor of clinical neurology at Columbia University in New York City and the National and Kapodistrian University of Athens, Greece, who was not involved with Dr. Holland's study.

"Flavonols may hold promise for promoting brain health," says David Seres, MD, associate professor of medicine at the Institute of Human Nutrition at Columbia University in New York City. "But we need long-term, randomized, controlled studies involving thousands of people willing to follow a diet for several years to show that flavonols affect the human brain and that those benefits reduce the risk for Alzheimer's."

One such study is the US Pointer trial, which began earlier this year. During the two-year intervention, which involves 2,000 participants, researchers will investigate the effects of a healthy diet, exercise, brain-stimulating activities, socialization, and controlling cardiovascular conditions (such as high blood pressure) on Alzheimer's disease and dementia risk. It's based on the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability, known as FINGER, in which participants who changed their habits experienced significant improvement in their thinking and memory compared with a control group.

"We estimate results in six or seven years," says Dr. Holland, assistant trial director and medical advisor for the study's branch at Rush University.

Until then, experts agree that a healthy diet is important for preventing poor blood circulation in the brain, which increases the risk of stroke, subtly damages small blood vessels, and contributes to vascular dementia, the most common cause of dementia after Alzheimer's disease. (Often people have both vascular dementia and Alzheimer's.)

To keep your brain in good shape, the experts recommend these lifestyle shifts:

Adopt healthy habits. "Flavonols are just one component of a healthy diet, and a healthy diet is just one part of prevention," says Dr. Holland. An easy checklist to follow to lower the risk for cerebrovascular disease is the American Heart Association's "Simple 7": Eat healthy, exercise, quit smoking, maintain a healthy weight, prevent or treat high blood pressure, check for and treat high blood sugar, and avoid or treat high cholesterol. Also, remain socially engaged and participate in brain-stimulating activities. In a Mayo Clinic study published in Neurology in August 2019, older adults who played card games, did crossword puzzles, used a computer, or did crafts had a lower risk for developing mild cognitive impairment than those who didn't.

Modify your meals. A good diet includes more produce and whole grains and less added sugar and saturated fats. "Try having a salad containing raw leafy greens every day or every other day, plus another cooked vegetable you like and some berries every day," suggests Dr. Holland. "Choose colorful fruits and vegetables, so you get a wide range of vitamins, minerals, and other beneficial bioactives—components such as flavonols that influence physiological and cellular activity in the body." Cook with seasonings like fresh dill, oregano, parsley, and tarragon; they all have flavonols. Tea, olive oil, oranges, and red wine contain small amounts of flavonols, but they were among the foods that contributed most to participants' total intake in the study.

Forgo supplements. "Although supplements may be needed for certain medical conditions, they are not a stand-in for healthy foods, which also provide vitamins, minerals, fiber, and healthy fats," says Dr. Holland.

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Check out "A Flavonol-Filled Meal" for a suggested dinner menu loaded with flavonols.

Flavonol-Rich Foods

In their flavonol study, researchers at Rush University in Chicago found that people who consumed the most flavonols overall had a lower risk for an Alzheimer's disease diagnosis than those who consumed the least. You won't find flavonols listed on the nutrition panel of food packages, but according to the US Department of Agriculture, these foods contain them:

• Almonds
• Apples, dried
• Apricots, dried
• Arugula
• Asparagus
• Beet greens
• Black beans
• Blueberries
• Broccoli
• Brussels sprouts
• Chinese cabbage
• Collard greens
• Cowpeas
• Cranberries
• Endive
• Figs, dried
• Golden raisins
• Kale
• Kidney beans
• Kohlrabi
• Mustard greens
• Okra
• Onions
• Pears, dried
• Pink beans
• Pinto beans
• Radicchio
• Red cabbage
• Rutabaga
• Salsa
• Scallions
• Sour cherries
• Spinach
• Sun-dried tomatoes
• Swiss chard
• Tomato paste
• Watercress
• White beans
• Zante currants