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Most of us have heard about the heart-healthy Mediterranean and blood-pressure-lowering DASH diets that may also guard against dementia.

According to a study, a hybrid of these two eating plans – called the MIND diet – is associated with a significantly lower risk of developing Alzheimer's disease. That's true even if you don't follow the diet strictly.

The newly created MIND diet (Mediterranean-DASH Intervention for Neurodegenerative Delay), developed by researchers from Rush University Medical Center in Chicago, was shown to reduce the likelihood of developing Alzheimer's by 53 per cent in people who followed it rigorously and by 35 per cent in those who adhered to it only modestly.

Alzheimer's disease, the most common cause of dementia, damages and kills brain cells, causing a steady deterioration in memory and thinking ability. It's not a normal part of aging, but your risk for the irreversible disease increases greatly after 65.

Along with elements from the Mediterranean and DASH diets, the MIND diet includes specific foods and nutrients found in past studies to be linked to optimal brain health. The diet's 10 "brain-healthy food groups" include green leafy vegetables, other vegetables, berries, nuts, beans, whole grains, fish, poultry, olive oil and wine.

The plan also advises that five unhealthy food groups – red meat, butter and stick margarine, cheese (because of its high saturated-fat content), pastries and sweets, and fried or fast food – be limited.

For the study, published last month in Alzheimer's & Dementia: The Journal of the Alzheimer's Association, the researchers analyzed the food intake of 923 community-dwelling Chicago residents, ages 58 to 98. Participants were scored on how closely their food intake matched the MIND diet, the Mediterranean diet or the DASH diet. (DASH stands for Dietary Approaches to Stop Hypertension.)

During a follow-up period of 4 1/2 years, 144 participants developed Alzheimer's disease.

All three diets, when closely followed, offered significant protection against Alzheimer's. The Mediterranean diet lowered Alzheimer's risk by 54 per cent, the MIND diet by 53 per cent and the DASH diet by 39 per cent.

Only the MIND diet, however, was shown to guard against Alzheimer's when not followed strictly. Participants who followed the plan moderately well were 35-per-cent less likely to develop the disease compared with those with the lowest adherence scores.

The findings also hinted that the longer a person follows the MIND diet, the greater the protection from Alzheimer's disease.

While this observational study shows promise for reducing the risk of Alzheimer's, it doesn't prove cause and effect. The results need to be confirmed by randomized controlled trials, the gold-standard evidence for a cause-and-effect relationship.

These new findings add to a growing body of evidence that strongly suggests your overall dietary pattern matters more than single nutrients when it comes to Alzheimer's prevention.

Eating a combination of healthful foods that deliver a wide range of protective nutrients while, at the same time, minimizing your intake of foods that may harm brain cells is what counts.

The MIND diet for optimal brain health

While we wait for other studies to confirm the protective link between the MIND diet and Alzheimer's risk, there's no reason to delay adopting this brain-friendly eating pattern. Follow the food guide below to earn the highest MIND diet score.

Leafy green vegetables: At least 6 servings/week

One serving: ½ cup cooked or 1 cup raw (e.g., salad greens)

Eating plenty of vegetables has been linked to a slower rate of cognitive decline in older adults, but leafy greens (e.g., spinach, kale, Swiss chard, beet greens, collards, rapini, broccoli, arugula, Romaine lettuce, leaf lettuce) seem to offer the greatest protection. Leafy greens are excellent sources of vitamin K, folate, beta-carotene and lutein, nutrients thought to help preserve brain functioning. (You'll get more beta-carotene and lutein if you eat your greens cooked rather than raw.)

Other vegetables: At least 1 serving/day

One serving: ½ cup cooked or raw vegetables

In addition to salad greens and green leafy vegetables, include other green vegetables (e.g., asparagus, green beans, green peppers), orange (e.g., carrots, sweet potato, butternut squash), yellow (e.g., yellow peppers), red (e.g., red peppers, tomato, beets), purple (e.g. eggplant, purple cabbage) and white/tan (e.g., onions, garlic, cauliflower, mushrooms) to consume a wide range of protective phytochemicals.

Berries: At least 2 servings/week

One serving: ½ cup

Berries are rich in polyphenols, phytochemicals that protect brain cells by fighting free-radical damage, reducing inflammation and removing toxic proteins that accumulate with age. Blueberries and strawberries appear to be most potent in terms of brain health.

Nuts: At least 5 servings/week

One serving: 1 ounce, about ¼ cup

Nuts (all types) help lower elevated blood pressure and LDL (bad) cholesterol and guard against Type 2 diabetes, factors that contribute to memory loss and Alzheimer's disease. Nuts are a good source of vitamin E; higher vitamin E levels are linked to less cognitive decline as we age.

Walnuts may be the king of nuts when it comes to brain health. Research suggests eating more walnuts can help improve memory, concentration and the speed at which your brain processes information. Walnuts deliver polyphenols (like berries) and an omega-3 fatty acid called alpha linolenic acid.

Legumes: At least 4 servings/week

One serving: ½ cup cooked

Lentils and beans (e.g., kidney beans, black beans, chickpeas), packed with low glycemic carbohydrates, provide a steady stream of fuel (glucose) to the brain. Plus, adding beans to your diet can help lower blood pressure and cholesterol.

Whole grains: At least 3 servings/day

One serving: 1 slice 100-per-cent whole-grain bread, ½ cup cooked brown rice, quinoa, whole-grain pasta, oatmeal, 1 cup 100-per-cent whole-grain, ready-to-eat breakfast cereal

Foods that promote a healthy cardiovascular system, such as whole grains, are also good for your brain. That's because your heart and blood vessels supply nutrient- and oxygen-rich blood to the brain. If your brain doesn't get the blood flow it needs, it can impair your memory and thinking abilities.

Fish: At least 1 serving/week

One serving: 3 ounces cooked

Oily fish such as salmon, trout, sardines and herring are plentiful in DHA, an omega-3 fatty acid essential for brain function. A higher intake of DHA is thought to slow brain aging and improve memory and thinking skills. It may also help prevent the build-up of an Alzheimer's-related protein called beta amyloid.

Poultry: At least 2 servings/week

One serving: 3 ounces cooked

As part of a healthy eating pattern, eating more poultry – and less red meat – is associated with a lower risk of Alzheimer's disease.

Olive oil: Use as your primary cooking oil

Olive oil is a rich source of monounsaturated fat, the type that helps reduce inflammation and prevents blood-vessel dysfunction. Extra-virgin olive oil also contains oleocanthal, a phytochemical that may boost production of two key enzymes believed to be critical in removing beta-amyloid from the brain.

Wine: One serving/day

One serving: 5 ounces

Studies suggest that one glass of wine per day helps preserve memory and reduces Alzheimer's risk. Low levels of alcohol are thought to have anti-inflammatory effects in the brain. Too much alcohol, however, can damage the brain.

Limit 'brain-unfriendly foods'

To get a top MIND diet score you must also limit butter/margarine to less than 1 tablespoon/day, fast or fried food less than once/week, red meat fewer than four times/week, cheese less than once/week and pastries and sweets less than five times/week.

Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto. She is a regular contributor to CTV News Channel;