Researchers found that losing a modest amount of weight while eating a healthy diet and less processed foods may help make the brain younger.
In a sub-study based on the Dietary Intervention Randomized Controlled Trial Polyphenols Unprocessed Study (DIRECT-PLUS), researchers from Ben-Gurion University of the Negev examined the brain aging effects of weight loss following an 18-month dietary intervention.
The DIRECT-PLUS study was the first to introduce the idea of a green-Mediterranean, high polyphenols diet. This diet differs from the traditional Mediterranean diet because it contains more polyphenol-rich foods and less red and processed meat.
Participants on this diet ate 28 grams of walnuts, three to four cups of green tea, and one cup of Wolffia-globosa (Mankai) plant green shake of duckweed every day for over 18 months. According to the researchers, Mankai is an appropriate substitute for meat because it's high in iron, B12, protein, and 200 types of polyphenols.
In this sub-study, published in eLife, scientists identified 102 participants with obesity from the DIRECT-PLUS trial. Each participant received a brain scan at the study's onset and conclusion. In addition, the researchers tested multiple health factors, such as blood biomarkers, throughout the study's duration.
After 18 months of the diet intervention, the scientists found that participants' brain age was nearly nine months younger after a 1% loss of body weight.
Moreover, younger brain age was associated with decreased liver fat and enzymes.
The scientists also found a link between slower brain aging and lower consumption of processed food, sweets, and beverages. However, increased green tea and walnut consumption did not impact brain age.
In a news release, study author Prof. Galia Avidan of the Department of Psychology at Ben-Gurion University says, "we were encouraged to find that even a weight loss of 1% was sufficient to affect brain health and lead to a 9-month reduction in brain age."
"Our study highlights the importance of a healthy lifestyle, including lower consumption of processed food, sweets, and beverages, in maintaining brain health," adds corresponding author Gidon Levakov, a former graduate student at the Ben-Gurion's Department of Cognitive and Brain Sciences.
Still, the study had some limitations. For example, the participants were primarily female, and the researchers did not use a non-dietary intervention control group.
Nonetheless, the study's findings add more evidence that dietary changes for weight loss can positively impact brain aging and may help researchers identify lifestyle interventions that benefit people with obesity.