Can Certain Foods Cause or Help Prevent Dementia?

We’re getting older. Life expectancy is set to breach 90 for the first time in history—women born in South Korea in 15 years’ time will have an average life expectancy of 90.8 years. With an older population, the aging brain becomes increasingly important: how can we keep our minds functioning better for longer?

It seems the answer is partly in what we’re eating. There is a growing body of evidence behind claims that eating certain foods can prevent—or cause—dementia. But don’t worry, it’s not all bad news. Experts say pouring yourself a glass of red wine could help stave off mental decline.

The Western diet: killing us cognitively?

The single biggest risk factor for dementia is age: the older you are, the higher your risk of cognitive decline. Since the global population is aging, this means we’re seeing an all-time high in cases of dementia and Alzheimer’s disease; according to Alzheimer’s Disease International, more than 46 million people have dementia today, and this will increase to over 131 million by 2050.

But Alzheimer’s disease and dementia are not a necessary part of aging, according to Neal Barnard of the George Washington University School of Medicine: “By staying active and moving plant-based foods to the center of our plates, we have a fair shot at rewriting our genetic code for this heart-wrenching, and costly, disease,” he said.

Three decades of research have revealed that a diet high in saturated fat and refined carbohydrates—the “Western diet”—can damage the networks in the brain, leading to memory loss, dementia and Alzheimer’s disease. A 2013 article published in the journal Appetite reviewed the research carried out in animals to date, concluding that eating a junk-filled Western diet really can slow our brains down.

As compelling as the result is, it looks backwards at studies carried out in the past, mostly using animals, not humans. If we want to truly understand the impact diet has on our brains, we need to follow groups of people eating different foods for a long period of time—an intervention trial. This is what a study launched in January this year aims to do.

Led by Martha Clare Morris, a nutritional epidemiologist at Rush University Medical Center, the study will include 600 people aged 65 to 84, who show no signs of decline in their brain function but who are obese and have “sub-optimal” diets. The participants will be put on one of two calorie-restricted diets and followed for three years to see if it keeps their minds sharp.

“While we know that there is a strong link between diet and health, intervention trials to examine whether a change in diet will help prevent Alzheimer's disease and other dementias have been largely neglected,” Morris said. “The results of this study should help us to improve brain health by developing new dietary guidelines for clinical use and for public health education.”

The mind-altering magic of the Mediterranean diet

One of the diets on trial is Morris’ own MIND diet, short for Mediterranean-DASH Intervention for Neurodegenerative Delay. It’s a mashup of two different diets: Mediterranean and DASH (Dietary Approach to Systolic Hypertension), which have both been shown to protect the brain.

The MIND diet sets out 10 foods to eat daily—green leafy vegetables, other vegetables, nuts, berries, beans, whole grains, fish, poultry, olive oil and wine—and five foods to avoid—red meats, butter and stick margarine, cheese, pastries and sweets, and fried or fast food.

When Morris studied 960 people over a decade to find out if the MIND diet worked, she found it slowed cognitive decline significantly: eating MIND foods kept people’s brains 7.5 years younger. So what’s the secret? Here’s the science behind the foods to put on your menu—and the ones to avoid—if you want to stay sharp.

Olive oil

Assessing the brain function, attention and memory of people aged 65-84 in Italy revealed that the more monounsaturated fatty acids like olive oil people consumed, the lower their cognitive decline. The researchers say this could be because fatty acids are needed to strengthen the membranes of our brain cells, keeping them strong. “It seems that, in the aging process, there is an increasing demand of unsaturated fatty acids,” the researchers commented.

Leafy greens

Research has shown that people who eat leafy greens regularly have the cognitive abilities of people 11 years younger. Antioxidants are good for neutralizing dangerous atoms called free radicals, which can damage cells and are thought to contribute to aging. Antioxidants called polyphenols are found naturally in plants and are abundant in leafy greens, helping reduce inflammation and the effects of free radicals on the brain.


Red wine also has a beneficial antioxidant ingredient: resveratrol has been shown to reduce the amount of beta-amyloid protein, the molecule that builds up in brain in Alzheimer’s disease.

It’s found in grapes, berries and peanuts but the researchers who studied its effects in mice are now trying to develop a stronger version: “Resveratrol in grapes may never reach the concentrations required to obtain the effect observed in our studies,” said Philippe Marambaud of the Litwin-Zucker Research Center for the Study of Alzheimer's Disease and Memory Disorders in New York.


In another study, berries—specifically blueberries and strawberries—delayed cognitive decline in older women by 2.5 years. The researchers attribute the effect to the high level of anthocyanidins, an antioxidant flavonoid, found in the berries.

“You can’t go wrong if a food has the word ‘berry’ in the name,” said Dr. Nussbaum, a member of scientific advisory board for the Alzheimer’s Foundation of America. “Strawberries, blueberries, cranberries— they’re all good for your brain.”


The MIND Diet recommends eating fish once a week, to add a healthy dose of omega-3 fatty acids. There is a link between consuming more omega-3 fatty acids and better brain functioning, and even a physically bigger brain.

Conversely, if you don’t have enough in your diet you could have a higher risk of developing Alzheimer’s disease. But as Dana Hunnes, senior dietician at Ronald Reagan UCLA Medical Center, told Live Science, it’s best to avoid the toxins that can build up in fish: “if you eat fish, it's a good idea to aim low in the food chain and look for sustainably fished (line and pole caught) products.”

So if we want to stave off dementia and Alzheimer’s disease as we age, changing our diets could be the best thing we can do. If you’re inspired and want some ideas about what to put on your brain-boosting menu, check out The Alzheimer's Prevention Cookbook: 100 Recipes to Boost Brain Health.

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