The DIRECT PLUS 18-month-long randomized control trial included 284 participants, who were divided into three groups according to diet: a healthy dietary guidelines group, a Mediterranean diet group, and a green Mediterranean diet group. In the green Mediterranean diet group, participants were provided 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 and processed meat. All three groups participated in physical activity programs based on aerobic exercise.
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 researchers identified “dramatic” changes in MRI-related brain atrophy, according to a press release. Those who adhered to either Mediterranean diet had less brain atrophy, with a greater effect in those who adhered to the green Mediterranean diet. Less brain atrophy was also associated with an improvement in insulin sensitivity.
The study was performed by Dr. Alon Kaplan and Iris Shai, Professor at Ben-Gurion University, Israel, and Adjunct Professor at Harvard University.
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"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,” explained Professor Shai in the press release. “Polyphenols can cross the blood-brain barrier (BBB), reduce neuroinflammation, and induce cell proliferation and adult-onset neurogenesis in the hippocampus.”Dr. Kaplan added: "Our findings might suggest a simple, safe, and promising avenue to slow age-related neurodegeneration by adhering to a green-Mediterranean diet.”
