This very common diet will rot your brain

If asked why they’ve decided to change their eating habits, most dieters will tell you they’re in pursuit of a slimmer appearance or overall healthier body. The findings of a new study, however, are making a strong case that we should all start eating better for our brains.

Researchers from the Rush University Medical Center report that a Western diet, characterized by red and processed meat, fried foods, pizza, refined grains, and full-fat dairy products, is linked to aggressive cognitive decline in adulthood and old age. Conversely, a Mediterranean diet, made up of fruit, vegetables, olive oil, legumes, potatoes, unrefined cereals, fish, and even the occasional glass of wine, appears to have a protective and beneficial effect on mental processes.

Western foods are so detrimental to brain health, study authors say that even people who mostly follow a Mediterranean diet won’t reap the cognitive benefits of all that healthy food if they regularly consume Western dishes as well. So, if you’ve decided to adopt a healthier diet in 2021, this study should serve as motivation not to fall back into bad habits. It doesn’t matter how many salads you eat if you’re also capping off every meal with some fried onion rings.

“Eating a diet that emphasizes vegetables, fruit, fish and whole grains may positively affects a person’s health,” says Puja Agarwal, Ph.D., a nutritional epidemiologist and assistant professor in the Department of Internal Medicine at Rush Medical College, in a release. “But when it is combined with fried food, sweets, refined grains, red meat and processed meat, we observed that the benefits of eating the Mediterranean part of the diet seems to be diminished.”

On the extreme ends of both spectrums, researchers say that the brain of an older adult who strictly follows a Mediterranean diet is likely close to six years younger from a cognitive functioning perspective in comparison to a daily Western diet eater.

“Western diets may adversely affect cognitive health,” Agarwal explains. “Individuals who had a high Mediterranean diet score compared to those who had the lowest score were equivalent to being 5.8 years younger in age cognitively.”

A massive dataset featuring 5,001 older adults (ages 65 and over) living in Chicago was used for this research. All of those people had been a part of the Chicago Health and Aging Project, a project focusing on cognitive health in older adults that spanned from 1993 to 2012. During that period, participants filled out cognitive assessments and surveys about their usual diets every three years.

Using all that long-term diet data, each participant was assigned a “total Mediterranean diet score” (0 to 55) indicating how healthy they were eating. Then, those scores were used to assess what impact individuals’ diets had on their cognitive scores (memory skills, perception speed, etc) over time.

Those showing the slowest rate of cognitive decline closely followed a Mediterranean diet. Meanwhile, people who ate lots of Western foods in conjunction with healthy foods didn’t appear to reap any of the cognitive benefits associated with a Mediterranean diet. 

Study authors also did a very thorough job of accounting for other potentially influential lifestyle factors, such as age, gender, education, and ethnicity, but say those calculations didn’t change anything. Across the board, people who ate a healthier diet had younger minds in old age. 

“The more we can incorporate green leafy vegetables, other vegetables, berries, olive oil, and fish into our diets, the better it is for our aging brains and bodies. Other studies show that red and processed meat, fried food and low whole grains intake are associated with higher inflammation and faster cognitive decline in older ages,” Agarwal concludes. “To benefit from diets such as the Mediterranean diet, or MIND diet, we would have to limit our consumption of processed foods and other unhealthy foods such as fried foods and sweets.”

Putting matters of the mind aside for a moment, a Mediterranean diet has also been shown to reduce the risk of cardiovascular disease, many forms of cancer, and diabetes. At this point, it’s hard to find a single reason why anyone shouldn’t switch from a Western diet to a Mediterranean approach to eating.

The full study can be found here, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association.