- A recent study looked at the health effects of a new version of the Mediterranean diet called the green Mediterranean diet.
- The green Mediterranean diet is more effective than the original at reducing the amount of visceral fat around internal organs.
- Visceral fat has been linked to early mortality and a host of other serious medical concerns.
- A key element of the new diet is the inclusion of walnuts, which are rich in polyphenols.
A new large-scale clinical intervention trial found that a modified Mediterranean diet — called the green Mediterranean diet — is more effective at reducing visceral fat that can surround and damage organs than the standard Mediterranean diet or a generally healthy diet.
All three diets resulted in a reduction of visceral fat, but the green Mediterranean diet doubled the benefit of the “traditional” Mediterranean diet.
The study was conducted by the DIRECT-PLUS trial research team. It was led by Prof. Iris Shai of Ben-Gurion University of the Negev, Israel, and Dr. Hila Zelicha, now at the University of California, Los Angeles, aided by colleagues from Italy, Germany, and the United States.
The study appears in
The green Mediterranean diet differs from the original Mediterranean diet in its emphasis on polyphenols.
Polyphenols are plant compounds that have been linked to protection from type 2 diabetes, some cancers, and heart disease. They also appear to support brain health and digestion.
Polyphenols are found in dark chocolate, berries, red wine, and tea, as well as some nuts, such as walnuts.
On the green Mediterranean diet, as envisaged in this study, a person consumes 28 grams of walnuts — about seven nuts — 3 to 4 cups of green tea, and 100 milligrams of the aquatic plant Wolffia globosa (Mankai) — also known as “duckweed” — in a smoothie or shake each day. All are rich in polyphenols.
Otherwise, the diet is the same as the original Mediterranean diet, but without the consumption of red and processed meats.
For the 18-month randomized controlled trial, researchers divided the 294 participants into three groups:
- one group followed a standard Mediterranean (MED) diet
- one followed a green Mediterranean (green-MED) diet
- a final group one strictly followed healthy dietary guidelines (HDG).
All groups were offered lifestyle educational sessions and physical activity recommendations, along with a free gym membership.
Researchers supplied the walnuts, tea, and Mankai, along with recipes for green smoothies.
“The clinical trial was conducted well, and these kinds of long-term diet interventions are very difficult to execute. The study has generated many hypotheses that can now be tested regarding the mechanism by which polyphenols affect VAT mass.”
“VAT” stands for “visceral adipose tissue,” which is another term for visceral fat. “Adipose” describes a body tissue that stores fat.
At the end of the trial, reductions in visceral fat were assessed via
Participants on the green Mediterranean diet reduced their visceral fat by over 14%. Those on the Mediterranean diet lost 6%, and the healthy diet group lost 4.2%.
While one’s overall weight and appearance are often the metrics by which people judge diets, visceral fat is a much more serious concern.
Dr. Zelicha told MNT that “in terms of the health risks associated with excess fat, visceral adipose tissue is much more dangerous than the extra ‘tire’ around your waist.”
“VAT,” said Dr. Zelicha, “has been linked to several health issues, such as
Visceral fat is deep in the body and found around internal organs, unlike the surface layer of fat that we can see.
“Most interventions currently available do not target deep adipose tissue specifically,” pointed out Dr. Cypess, “yet benefits of fat mass loss, in general, are still valuable.”
Since it cannot be seen, determining if one has VAT is not a simple endeavor. While Dr. Zelicha noted that waist circumference is a fairly good indicator of the presence of VAT, MRI and computer tomography (CT) scans are the gold standards for detection.
“However, CT involves ionizing radiation, and MRI has emerged as a powerful non-invasive prediction tool, but it is very expensive and time-consuming,” she cautioned.
There is still a need, Dr. Zelicha said, for a better, easily accessible, and validated tool for assessing VAT.
As of the time of writing, the green Mediterranean diet is the regimen that most significantly reduces visceral fat, according to the recent research.
As Dr. Cypess noted: “Most diets lead to a reduction in the adipose tissue around organs. Even in this study, the HDG control arm led to visceral fat loss, just not as much as the [green Mediterranean] diet.”
Since effective diets will typically deliver at least some reduction in VAT, Dr. Cypess asserted, “the best diet and exercise plan is the one that the person can adhere to for months and years into the future.”
Dr. Zelicha said that aerobic exercises such as running or cycling have “been shown to be a powerful strategy for visceral adipose tissue reduction.“
In Prof. Shai’s earlier research, such exercise along with walnut consumption amplified the effect of the standard Mediterranean diet in reducing VAT, said Dr. Zelicha.
“Eating more plant-based fats,” suggested Dr. Zelicha, “such as olive oil, avocados, nuts, and seeds, and avoiding simple carbohydrates and trans-fatty acids can help reduce VAT.”