The green Mediterranean diet, a twist on the standard Mediterranean diet with an enrichment in polyphenols and low in red and processed meat, proved to have the strongest ties to markers of brain health in an 18-month controlled feeding study conducted by researchers at Ben-Gurion University.
 
In the study, 284 participants between the ages of 31 and 82 were divided into three groups according to diet, and whole brain MRI measurements were taken before, and after the trial. Hippocampal-occupancy (HOC) and lateral-ventricle-volume (LVV) were measured as indicators of brain atrophy and predictors of future dementia. Brain MRI-derived data were quantified and segmented using NeuroQuant, an FDA-authorized fully automated tool. 
 
The participants consumed a diet matching either the healthy dietary guidelines, the Mediterranean diet, or the green Mediterranean diet, a version of the former dietary pattern which included enrichment with high-polyphenol green components – 3-4 daily cups of green tea and a daily green shake of Mankai duckweed as a substitute for dinner, with minimal consumption of red and processed meat.
 
All three groups participated in aerobic exercise, and were given free gym memberships. The researchers identified dramatic changes in MRI-related brain atrophy markers within 18-24 months, where the rates of brain atrophy markers were significantly accelerated from the ages of 50 and up. However, the green-MED group, especially participants over the age of 50, saw a significant magnitude of attenuation of the brain atrophy markers. Improved insulin sensitivity was also independently associated with attenuated brain atrophy.
 
Greater Mankai, green tea, and walnut consumption, along with reductions in red and processed meat, were significantly associated with lower hippocampal occupancy decline, the authors concluded.
 
“The beneficial association between the green Mediterranean diet and age-related neurodegeneration might be partially explained by the abundance of polyphenols in plant-based food sources which have antioxidant and anti-inflammatory metabolites. Polyphenols can cross the blood-brain barrier (BBB), reduce neuroinflammation, and induce cell proliferation and adult-onset neurogenesis in the hippocampus,” Iris Shai, co-lead author of the study, said.
 
“Our findings might suggest a simple, safe, and promising avenue to slow age-related neurodegeneration by adhering to a green Mediterranean diet,” Dr. Alon Kaplan, co-lead author of the study, concluded.