Mediterranean diet may lower brain age and improve cognitive health, study finds

06 Jun 2023 --- Following a green Mediterranean diet, which is higher in dietary polyphenols and lower in red and processed meats, could reduce the risk of neurological conditions by lowering weight and brain age. The lifestyle intervention also decreased liver fat and enzymes that have been found to affect brain health in Alzheimer’s disease.

In an 18-month clinical trial conducted by a team of Israel-based researchers, participants followed an adapted Mediterranean diet. Researchers scanned participants’ brains at the start and end of the program and tested liver biomarkers.

“A 1% reduction in body weight led to the participants’ brains appearing nearly nine months younger than expected after 18 months,” Gidon Levakov, Ph.D. at Ben Gurion University of the Negev, Israel, tells NutritionInsight. 

The green Mediterranean diet used in the study has been shown to have several health benefits. Levakov adds, “We don’t think that just any diet would have the same effect on brain health.”  

“Our analysis of food consumption reports completed by participants indicated that reduced consumption of processed food, sweets and beverages was linked to attenuated brain aging.”

The authors note further research is critical to understand why and to validate these findings in more extensive and diverse populations. 

Obesity has been linked with the brain aging faster than normally expected.Reducing risk factors 
Obesity has been linked with the brain aging faster than normally expected. The direct benefits of having a younger brain would reduce risk factors for various conditions, explains Levakov. 

“Increased brain age relative to the chronological age was shown to be linked to several neurological conditions such as mild cognitive impairment, Alzheimer’s disease, schizophrenia and depression and is associated with an increase in mortality rate.” 

“It is important for people to realize that what they eat is reflected not only in their body weight or appearance but has strong implications for their brain health.” 

The researchers note the extent of the observed effect was more significant than expected. 

“At the clinical level, the study provides a very positive outcome as it implies that the trajectory of brain health could be modified and so it may give a strong incentive for people to modify their nutrition and lifestyle,” adds Levakov. 

“At the theoretical level, it paves the way to our understanding of the neural basis of brain aging in relation to nutrition.” 

Obesity and the brain
The researchers developed a model based on MRI brain scans to predict the brain age of 102 overweight study participants in the Dietary Intervention Randomized Control Trial Polyphenols Unprocessed Study (DIRECT-PLUS) trial. 

Participants received dietary guidance combined with physical activity. They were divided into one of three food intervention groups, following either a Mediterranean diet, a green Mediterranean diet or healthy dietary guidelines in the control group. 

Both Mediterranean diet groups consumed a diet rich in vegetables, replacing beef and lamb with poultry and fish and consuming 28 g per day of walnuts. The green Mediterranean diet group drank three to four cups of green tea daily and a green shake with Wolffia globosa. Known as duckweed, this plant is high in iron, vitamin B12, different polyphenols – plant compounds with several health benefits – and protein. 

“In the current study, we found a beneficial effect of weight loss on brain age attenuation in all intervention groups,” explains Levakov. 

Participants following a green Mediterranean diet consumed green tea per day and a green shake with Wolffia globosa.At the same time, the Mediterranean diet has been linked to a reduction of Alzheimer’s disease-related biomarkers and lower dementia risk in earlier research. 

“The specific [green-Mediterranean] diet chosen has been shown in many other studies to have important health benefits for other physiological systems as well as for the brain. It induces changes that go far beyond just weight loss,” highlights Levakov.  

Benefits to non-obese people  
As the current study, published in eLife, was conducted with overweight and obese individuals, the researchers would like to examine whether the diet may have similar implications to individuals with average weight, explains Levakov. 

“We expect that a healthy diet would also benefit people who are not obese, given the widespread physiological benefits of the green Mediterranean diet that were documented in other sub-studies of the DIRECT-PLUS intervention.”

“In the future, we would certainly like to examine further aspects such as gender differences which we could not assess in the current sample.” 

Levakov adds that the researchers would like to understand the variability within the sample better to determine why a specific intervention is beneficial for some individuals rather than others. “We also need to understand the cognitive benefits of the intervention and the resultant improvement in brain age.” 

“These lines of research would help us to better tailor personalized lifestyle and dietary interventions in the future that would lead to maximal impact on brain and cognitive health,” concludes Levakov. 

By Jolanda van Hal