Green-Mediterranean diet reduces non-alcoholic fatty liver disease

A green Mediterranean diet reduces intrahepatic fat more than other healthy diets and cuts non-alcoholic fatty liver disease (NAFLD) in half, according to a new study by Ben-Gurion University (BGU) of the Negev researchers and a team of international colleagues, published in the journal Gut.

The MRI-nutritional clinical trial, called Direct-Plus, conducted by an international research team is the first to develop and test a new green Mediterranean diet. This modified Mediterranean diet is rich in vegetables, includes daily intake of 28 grams of walnuts, and less processed and red meat. It is enriched with green components, high in polyphenols, including three to four cups of green tea per day and 100 grams frozen cubes per day of a Mankai green shake. Mankai, an aquatic green plant also known as duckweed, is high in bioavailable protein, iron, B12, vitamins, minerals, and polyphenols, according to the study.

This 18-month trial began in 2017 at the Nuclear Research Center Negev in Dimona, Israel, when 294 workers in their fifties with abdominal obesity were randomly divided into three groups: healthy dietary regimen, Mediterranean diet, and green Mediterranean diet. In addition to the diet, all the participants were given a physical exercise regimen with a free gym membership. The participants underwent MRI scans to quantify the exact proportion of excess intrahepatic fat before and after the trial.

The results showed that every diet led to liver fat reduction. However, the green MED diet resulted in the greatest reduction of hepatic fat, down 39 percent, as compared to the traditional Mediterranean diet, down 20 percent, and the healthy dietary guidelines, down 12 percent. The results were significant after adjusting for weight loss, the researchers said.

Overall, the green MED diet produced dramatic reductions in fatty liver. NAFLD prevalence dropped from 62 percent at baseline to 31.5 percent in the green Mediterranean group, down to 47.9 percent in the Mediterranean group and 54.8 percent in the healthy dietary regimen group. Specifically, greater Mankai and walnut intake and less red and processed meat intake were significantly associated with the extent of intrahepatic fat (IHF) loss, after controlling for other variables. Both Mediterranean diet groups had significantly higher total plasma polyphenol levels. More specific polyphenols, found in walnuts and Mankai, were detected in the green Mediterranean diet group. The researchers said they hypothesize the effect of polyphenols and the reduction in red meat play a role in liver fat reduction.

NAFLD affects 25 percent to 30 percent of people in the United States and Europe. While some fat is normal in the liver, excessive fat of 5 percent or higher leads to insulin resistance, type 2 diabetes, and cardiovascular risk, as well as decreased gut microbiome diversity and microbial imbalance. Since no drug is currently available to treat fatty liver, the only intervention is weight loss and curtailing of alcohol consumption, the researchers said.

"Our research team and other groups over the past 20 years have proven through rigorous randomized long-term trials that the Mediterranean diet is the healthiest," says Iris Shai, PhD, lead researcher an epidemiologist in the BGU School of Public Health who is also an adjunct professor at the Harvard T.H. Chan School of Public Health, in a statement. "Now, we have refined that diet and discovered elements that can make dramatic changes to hepatic fat and other key health factors."