Including unhealthy foods can lessen the positive effects of a healthy diet

Eating a healthy diet, like the Mediterranean diet, has a positive impact on health, but little is known about the effects of including unhealthy foods in a healthy diet. Now, researchers at Rush University Medical Center have reported diminished benefits of a Mediterranean diet among those with a high frequency of eating unhealthy foods. The results of his study were published in Alzheimer’s and dementia: The Journal of the Alzheimer’s Association on January 7th.

“Eating a diet that emphasizes vegetables, fruits, fish and whole grains can positively affect a person’s health,” said Puja Agarwal, Ph.D., nutritional epidemiologist and assistant professor in the Department of Internal Medicine at Rush Medical College. “But when it is combined with fried foods, sweets, refined grains, red meats and processed meats, we see that the benefits of eating the Mediterranean part of the diet seem to diminish.”

A Mediterranean diet is associated with slower rates of cognitive decline in older adults.

The observational study included 5,001 elderly Chicago residents who were part of the Chicago Health and Aging Project, an assessment of cognitive health in adults over 65 conducted from 1993 to 2012. Every three years, study participants completed a cognitive assessment questionnaire that tested basic information processing and memory skills, and completed a questionnaire on the frequency with which they consumed 144 food items.

The researchers analyzed the degree of adherence of each of the study participants to the Mediterranean diet, which includes daily consumption of fruits, vegetables, vegetables, olive oil, fish, potatoes and unrefined cereals, in addition to moderate consumption of wine. They also assessed how much each participant followed a Western diet, which included fried foods, refined grains, sweets, red and processed meats, whole dairy products and pizza. They assigned scores from zero to five for each food item to compile a total Mediterranean diet score for each participant over a range of zero to 55.

The researchers then examined the association between Mediterranean diet scores and changes in participants’ overall cognitive function, episodic memory and perceptual speed. Participants with slower cognitive decline over the years of follow-up were those who adhered more to the Mediterranean diet, along with limiting foods that are part of the Western diet, while participants who ate more of the Western diet had no beneficial effect of healthy food components. in reducing cognitive decline.

There was no significant interaction between age, sex, race or education and the association with cognitive decline at high or low levels of Western diet foods. The study also included models for smoking, body mass index and other potential variables, such as cardiovascular conditions and the results remained the same.

“Western diets can adversely affect cognitive health,” said Agarwal. “Individuals who scored high on the Mediterranean diet compared to those who scored lowest were equivalent to being 5.8 years younger in cognitive age.”

Agarwal said the results complement other studies that show that a Mediterranean diet reduces the risk of heart disease, certain types of cancer and diabetes and also supports previous studies on Mediterranean diet and cognition. The study also notes that most dietary patterns that showed improvement in cognitive function among older adults, including the Mediterranean, MIND and DASH diets, have a unique scoring matrix based on the amount of servings consumed for each component of the diet.

“The more we can incorporate green leafy vegetables, other vegetables, berries, olive oil and fish into our diets, the better it will be for our aging brains and bodies. Other studies show that red and processed meat, fried foods and low-content whole grains ingestion is associated with greater inflammation and faster cognitive decline at older ages, “said Agarwal. “To benefit from diets like the Mediterranean diet, or the MIND diet, we would have to limit our consumption of processed foods and other unhealthy foods, such as fried and sweet foods.”

The study and its results cannot be generalized easily. Future longitudinal studies on diet and cognition among the middle-aged population are needed to extend these findings.