Does the Mediterranean Diet Really Decrease Your Risk of Dementia?

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A new study suggests that a Mediterranean diet may not protect against cognitive decline and dementia, despite what other research has shown. Selim Aksan/Getty Images
  • New research suggests that the Mediterranean diet and adherence to related dietary recommendations showed no significant association with a reduced risk of dementia.
  • Previous studies have shown mixed results on the effects of the Mediterranean diet and dementia risk.
  • While there are many health benefits of following a Mediterranean eating pattern, it is not the only factor to take into consideration when it comes to reducing your risk for dementia.

The Mediterranean diet is a healthy, mostly plant-based eating style, which includes vegetables, fruits, whole grains, and healthy fats, such as fish and olive oil. The U.S. World and News Report has ranked the Mediterranean diet as the best diet in the world for 5 consecutive years.

Previous studies have shown that people who follow healthful eating patterns such as the Mediterranean diet may have a reduced risk of dementia.

But a new study suggests that the Mediterranean diet may not be linked to a reduced risk of dementia after all.

The research, published today in the online issue of the journal Neurology, examined 28,000 participants from Sweden over a 20-year period.

Participants had an average age of 58 and did not have dementia at the start of the study. They filled out a weekly food diary, and a food frequency questionnaire, and participated in an interview. At the conclusion of the study, 1,943 people, or nearly 7%, were diagnosed with dementia, which included Alzheimer’s disease (AD) and vascular dementia.

“While our study does not rule out a possible association between diet and dementia, we did not find a link in our study, which had a long follow-up period, included younger participants than some other studies, and did not require people to remember what foods they had eaten regularly years before,” study author Dr. Isabelle Glans, research and doctoral student at Lund University in Sweden, said in a news release.

Despite the new findings, however, study authors noted that further research is still needed.

Prior studies have yielded mixed results on the effects of the Mediterranean diet and dementia risk.

For instance, a 2018 study indicates there may be as much as a 3.5-year delay in the progression of Alzheimer’s disease among those who follow a Mediterranean diet for several years compared to a traditional Western diet.

In addition, a 2015 study suggests that a Mediterranean diet is associated with an improvement in brain function among older people.

Still, another large-scale study from 2015 examined long-term adherence to the Mediterranean diet and cognitive function in women and shows only moderate improvements in cognition. The findings do not show a consistent association with reducing cognitive decline and are not associated with a reduced risk for dementia.

There are many factors contributing to dementia and cognitive decline, with lifestyle, genetics, and diet all playing a role.

Dana Ellis Hunnes, PhD, MPH, RD, clinical dietitian at UCLA Medical Center, adjunct professor at UCLA’s Fielding School of Public Health, and author of “Recipe For Survival,” said the Mediterranean diet may possibly reduce dementia risk due to its high levels of antioxidants and anti-inflammatory compounds that are naturally occurring in plant-based foods, healthy monounsaturated fats, whole grains, nuts, and seeds.

But most evidence on the effectiveness of the Mediterranean diet on brain health is derived from observational studies, said nutrition expert Keith-Thomas Ayoob, EdD, RD, associate clinical professor emeritus of pediatrics at the Albert Einstein College of Medicine in New York City.

“There are clinical trials, like the PREDIMED study, that actually give people extra virgin olive oil and nuts to eat daily (to take and eat at home) that show benefits for cardiovascular health and reduced risk of other conditions, such as type 2 diabetes and hypertension,” Ayoob told Healthline.

“It’s hard to do this type of clinical study though for dementia, as it takes so long and measuring compliance in free-living populations is always iffy.”

The Mediterranean diet encourages the consumption of nutrient-rich whole foods including fruits and vegetables, whole grains, fatty fish, and lower amounts of foods high in saturated fat.

The MIND diet (Mediterranean-DASH Diet Intervention for Neurodegenerative Delay) is a combination of the Mediterranean diet and the DASH diet (Dietary Approaches to Stop Hypertension). It focuses more on the weekly consumption of foods like beans, berries, nuts, whole grains, leafy veggies, etc., and recommends low-fat and fat-free dairy foods.

Both Mediterranean and MIND diets encourage physical activity and support heart health and the prevention of hypertension.

The eating patterns are also high in antioxidants and anti-inflammatory. Ayoob said that both diets protect against oxidative damage to blood vessels, which may help reduce the risk of dementia.

But research favors the MIND diet for improved brain health in older adults, Ayoob noted. Of course, nothing in research is absolute, so not all studies may support this claim.

While the Mediterranean diet and the MIND diet may offer reduced risk for cognitive decline, Ayoob said that neither diet offers guaranteed protection against dementia or any other chronic condition.

Contrary to prior studies showing that the Mediterranean diet may help lower dementia risk, new research suggests otherwise.

Be that as it may, the study authors noted that further, more vigorous studies are still needed.

While nutritionists agree there are many health benefits to following a Mediterranean diet, other factors, such as genetics and lifestyle, may play a role in cognitive decline and the development of dementia. A person’s diet may not always be enough on its own to offer a protective effect.

If you’re an older adult at risk for cognitive decline and are interested in how food, lifestyle, and genetics may factor in, you may wish to speak with your doctor about what you can do to preserve and potentially boost your brain health.

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