May 16, 2022
JERUSALEM WEATHER

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It seems to be true that you are what you eat. Researchers at Ben-Gurion University (BGU) of the Negev in Beersheba have found that a green Mediterranean diet, high in polyphenols – micronutrients found naturally in fruits, vegetables, nuts, teas, and certain spices and low in red and processed meat, seems to slow age-related brain atrophy. 

The DIRECT PLUS 18-month-long, randomized and controlled trial, which included 300 participants, is one of the longest and largest brain MRI (magnetic resonance instrument) trials in the world.

Prof. Iris Shai
Photo Credit: Dani Machlis/for Ben-Gurion University

Their findings were just published in The American Journal of Clinical Nutrition under the title “The effect of a high-polyphenol Mediterranean diet (GREEN-MED) combined with physical activity on age-related brain atrophy: the DIRECT PLUS randomized controlled trial.” The effect of diet on age-related brain atrophy has been largely unproven until now. 

Participants underwent 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, a fully automatically tool approved by the US Food and Drug Administration (FDA). 

A total of 284 men and women (88% men) aged 31 to 82 were randomly divided into three groups – a healthy dietary guidelines group, a Mediterranean diet group and a green Mediterranean diet. In the Mediterranean diet group, the participants were further provided walnuts rich in polyphenols. In the green-Mediterranean group, the participants were further provided high polyphenol green components – three or four 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. In addition, all three groups participated in physical activity programs based on aerobic exercise, including free gym memberships. 

Mankai is a new high-protein aquatic plant strain of duckweed, with significant potential as a superfood and provides glycemic control after carbohydrate consumption. Mankai boasts a well-rounded nutritional profile and is rich in minerals including iron, magnesium and zinc; vitamins such as vitamin A, E, B12 (which is rarely found in plants) and folic acid; omega-3 fatty acids, polyphenols and phytosterols, all packed in its very compact leaves. Its protein profile, which consists of about 45% of its dry matter, is extremely close to that of an egg, the nutritional gold standard for protein.

The trial was performed by Dr. Alon Kaplan and BGU Prof. Iris Shai, who is also an adjunct professor at Harvard University, together with several international teams of brain experts. 

The researchers were surprised to identify dramatic changes in MRI-related brain atrophy within 18 to 24 months, whereas the rate of brain atrophy markers (hippocampal occupancy decline and lateral ventricle volume expansion) was significantly accelerated from the age of 50 years and up. 

The researchers discovered a significant attenuation in brain atrophy over the 18 months in those who adhered to both Mediterranean diets; with greater magnitude in the green-MED group, specifically among participants over age 50. In addition, the researchers noticed that an improvement in insulin sensitivity was independently associated with attenuated brain atrophy. 

Greater consumption of Mankai, green tea, and walnuts consumption and less red and processed meat consumption were significantly associated with lower hippocampal occupancy decline. Participants were initially chosen based on waist size or high levels of “bad cholesterol” and other fats in the blood. They were all employees at a remote workplace in Israel (the Nuclear Research Center in Dimona) where they did not leave the premises during the workday, and the lunch provided was monitored. 

“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,” said Shai, the lead author. “Polyphenols can cross the blood-brain barrier (BBB), reduce neuroinflammation, and induce cell proliferation and adult-onset neurogenesis in the hippocampus.”

“Our findings might suggest a simple, safe, and promising avenue to slow age-related neurodegeneration by adhering to a green-Mediterranean diet,” added Kaplan.