Should you try the green Mediterranean diet?

A plant-based riff on Med-style eating is gaining buzz for its potential health advantages. Here’s how the science stacks up so far.
Published June 3, 2021

Some might argue that it’s tough to improve on the traditional Mediterranean diet. With its emphasis on fruits, veggies, whole grains, fish, healthy fats like olive oil and nuts; and its smaller amounts of dairy, eggs, poultry, and red and processed meats, this eating approach has long been a star in nutrition circles. Compared with diets that are higher in meat and refined carbs, Mediterranean-style eating has been linked to better long-term weight management, a lower risk of developing conditions such as cardiometabolic disease, certain cancers, type II diabetes, and Alzheimer’s disease; and lower all-cause mortality in general.

If it ain’t broke, don’t fix it—right? Not so fast, according to researchers who have tweaked the classic Mediterranean diet in hopes of creating an even healthier “green” version that pumps up the plant quotient and further reduces animal protein.

What exactly does the green Mediterranean diet entail—and do the benefits beat those of its predecessor? Keep reading for the lowdown so you can decide whether this plant-forward eating style is worth a try.

What is the green Mediterranean diet?

The green Mediterranean diet is a newish eating approach in the early stages of investigation, says Iris Shai, PhD, a professor in the nutrition departments at Harvard T.H. Chan School of Public Health and Ben-Gurion University of the Negev in Israel. The goal? To see whether it’s possible to “upgrade the traditional healthy Mediterranean diet by amplifying the polyphenol content and reducing meat,” Dr. Shai explains. Polyphenols are micronutrients found in plant foods.

Dr. Shai led a research team that followed a small sample of 294 adults who had abdominal obesity for 18 months. In a pair of studies published in the journals Heart and Gut in 2020 and 2021, volunteers were split into three groups:

  • Group 1: received general guidelines for healthy eating with no restrictions on calorie intake.
  • Group 2: followed a traditional Mediterranean diet, with calories capped at 1,200–1,800 per day. In keeping with the traditions of this eating approach, participants were advised to limit red meat and avoid processed meat altogether. Poultry and fish were permitted. Volunteers in this group also ate about ¼ cup of walnuts each day.
  • Group 3: followed a “green” version of the Mediterranean diet with similar calorie limits and a daily dose of walnuts. (The California Walnut Commission helped fund the research.) The differences were that volunteers in this group were told to avoid both red and processed meats, and to limit poultry. In addition, people in this group drank 3 or 4 cups of green tea every day, along with a plant-based protein shake we’ll describe in a sec.
What are the potential health benefits of the green Mediterranean diet?

After six months, both calorie-restricted versions of the Mediterranean diet were associated with similar magnitudes of weight loss—about 12 to 14 pounds on average. (Meanwhile, volunteers in the healthy-advice group lost about 3 pounds.) But those in the green Mediterranean diet group saw the greatest reductions in harmful LDL cholesterol, diastolic blood pressure, and markers of inflammation.

The researchers also found that participants following the green Mediterranean diet lost twice as much liver fat as those in the traditional Mediterranean diet group (and three times as much as those in the healthy-advice group). While this study wasn’t designed to measure long-term health outcomes, Dr. Shai notes that reductions in liver fat may reduce the risk of liver disease and cardiovascular disease.

Which foods can you eat on the green Mediterranean diet?

Whereas the traditional Mediterranean diet doesn’t preach avoidance of particular foods, the green Mediterranean version is more focused on making replacements, says Samantha Cochrane, a registered dietitian at the Ohio State University Wexner Medical Center who was not involved in the green Mediterranean studies. Here’s a bit more about the foods the research has focused on:

  • Duckweed: The study volunteers who skipped meat instead drank smoothies containing a commercial preparation of this edible, aquatic plant. Scientifically known as Wolffia globosa, duckweed is high in protein, as well as vitamin B12—a nutrient more commonly found in meat, dairy, and eggs. For those not familiar, Dr. Shai notes that “duckweed has been consumed for hundreds of years, mainly in Laos, Vietnam, and Thailand. It’s quite neutral in taste.”
  • Walnuts: These popular faves are a rich source of healthy fats and may have antioxidant and anti-inflammatory properties.
  • Green tea: Rich in multiple polyphenols, green tea may have contributed to some beneficial effect in reducing risks of heart disease, diabetes, and other conditions.
Do I need these exact foods to get the benefits?

It’s too soon to say for sure, but Cochrane doubts that the trio of duckweed, walnuts, and green tea form some unique silver bullet against disease. “Even though we might not be able to draw the conclusion that these specific plant-based foods are helpful for everybody, I think it can still tell us there’s some good nutrition to be had in increasing how much of the plant-based foods you’re including,” she says. “For me, [this research] just reinforces that there are lots of benefits from plant-based foods.”

In other words, if you can’t find duckweed products at your local supermarket—or if green tea and walnuts just aren’t your jam—other plant-based foods could conceivably provide similar benefits.

For plant-based proteins, Cochrane suggests nuts, legumes, seeds, and beans. Beyond plants, she’s also a fan of fatty fish, like salmon, which was included in the studies.

As for the polyphenol aspect, “Polyphenols are found in a good variety of plant-based foods,” Cochrane says. “Fruits, vegetables, things that come from plants—like cocoa and chocolate, seasonings, herbs … They all have different varieties of polyphenols.”

Is the green Mediterranean diet safe?

Not if you’re allergic to nuts! That aside, keep in mind that the green Mediterranean diet has only been studied in the context of calorie restriction, which might not jibe with your personal energy requirements.

“The calorie levels that were given were generalized, so following what was in the study might not be right for everybody,” Cochrane says. Beyond that, Cochrane says she doesn’t have any specific concerns regarding walnuts, green tea, or duckweed. Echoing advice from the WW science team, Cochrane recommends speaking with a qualified nutrition pro or your healthcare provider before making any major change to your diet.

Another point to remember: Unless the parameters of the green Mediterranean diet align with your actual food preferences, the regimen might be tough to keep up long-term.

“It’s not always attainable or sustainable to replace [animal] protein with a plant-based protein,” Cochrane says. “If we can incorporate more vegetables and plant-based proteins, that’s great. But to go strictly plant-based can be hard for some people.”

Bottom line: Should you try the green Mediterranean diet?

The green Mediterranean diet, an updated riff on classic Med-style eating, is in the early stages of study. Studies so far have roughly defined the green Mediterranean diet as an eating pattern that centers plant-based foods, with special emphasis on walnuts, green tea, and protein-rich duckweed. The green Mediterranean diet also nixes red meat and poultry. Compared with a traditional Mediterranean-style diet, which prioritizes plant-based foods while including some measure of meat, the green version has been associated with healthier measures of blood cholesterol, liver fat, and inflammation.

At the end of the day, it’s probably worth remembering that a healthy pattern of eating is not a contest between specific foods. Says Cochrane, “Increasing your variety of fruits, vegetables, grains, nuts, and plant-based proteins—that can definitely increase the nutrient profile of your overall diet and really encourage good health.”


Heeseung Kim is a freelance journalist and editor specializing in health, wellness, and sustainability topics.