Summary: A modified version of the Mediterranean diet called the green Mediterranean diet, which consists of enriched dietary polyphenols such as green tea, walnuts, and duckweed, and decreased red meats, reduced more visceral fat than the traditional Mediterranean diet or a traditional diet plan.
Source: Ben-Gurion University of the Negev
The green Mediterranean diet (MED) significantly reduces visceral adipose tissue, a type of fat around internal organs that is much more dangerous than the extra “tire” around your waist.
The green Mediterranean diet was pitted against the Mediterranean diet and a healthy diet in a large-scale clinical interventional trial- the DIRECT PLUS. Subsequent analysis found that the green Med diet reduced visceral fat by 14%, the Med diet by 7% and the healthy diet by 4.5%.
The study was published in BMC Medicine.
Reducing visceral fat is considered the true goal of weight loss as it is a more important indicator than a person’s weight or the circumference of their waist. Visceral fat aggregates over time between organs and produces hormones and poisons linked to heart disease, diabetes, dementia and premature death.
The research was led by Prof. Iris Shaiof Ben-Gurion University of the Negev, Israel, an adjunct Professor from the Harvard School of Public Health, and an Honorary Professor, University of Leipzig, Germany, together with her doctoral student Dr. Hila Zelicha and Italian, German, and American colleagues.
The DIRECT-PLUS trial research team was the first to introduce the concept of the green-Mediterranean diet. This modified MED diet is further enriched with dietary polyphenols and lower in red/processed meat than the traditional healthy MED diet. On top of a daily intake of walnuts (28 grams), the participants consumed 3-4 cups of green tea/day and 100 grams (frozen cubes) of duckweed green shake/day. The aquatic green plant duckweed is high in bioavailable protein, iron, B12, vitamins, minerals, and polyphenols and substituted meat intake.
The team has shown in previous studies that the green MED diet has a variety of salutary effects ranging from the microbiome to age-related degenerative diseases.
Two hundred and ninety four participants took part in the 18-month long trial.
“A healthy lifestyle is a strong basis for any weight loss program. We learned from the results of our experiment that the quality of food is no less important than the number of calories consumed and the goal today is to understand the mechanisms of various nutrients, for example, positive ones such as the polyphenols, and negative ones such as empty carbohydrates and processed red meat, on the pace of fat cell differentiation and their aggregation in the viscera,” says Prof. Shai.
“A 14% reduction in visceral fat is a dramatic achievement for making simple changes to your diet and lifestyle. Weight loss is an important goal only if it is accompanied by impressive results in reducing adipose tissue,” notes Dr. Hila Zelicha.
Funding: This work was funded by grants from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project number 209933838- SFB 1052; the Rosetrees trust (grant A2623); Israel Ministry of Health grant 87472511; Israel Ministry of Science and Technology grant 3-13604; and the California Walnuts Commission.
None of the funding providers was involved in any stage of the design, conduct, or analysis of the study and they had no access to the study results before publication.
The effect of high-polyphenol Mediterranean diet on visceral adiposity: the DIRECT PLUS randomized controlled trial
Mediterranean (MED) diet is a rich source of polyphenols, which benefit adiposity by several mechanisms. We explored the effect of the green-MED diet, twice fortified in dietary polyphenols and lower in red/processed meat, on visceral adipose tissue (VAT).
In the 18-month Dietary Intervention Randomized Controlled Trial PoLyphenols UnproceSsed (DIRECT-PLUS) weight-loss trial, 294 participants were randomized to (A) healthy dietary guidelines (HDG), (B) MED, or (C) green-MED diets, all combined with physical activity. Both isocaloric MED groups consumed 28 g/day of walnuts (+ 440 mg/day polyphenols). The green-MED group further consumed green tea (3–4 cups/day) and Wolffia globosa (duckweed strain) plant green shake (100 g frozen cubes/day) (+ 800mg/day polyphenols) and reduced red meat intake. We used magnetic resonance imaging (MRI) to quantify the abdominal adipose tissues.
Participants (age = 51 years; 88% men; body mass index = 31.2 kg/m2; 29% VAT) had an 89.8% retention rate and 79.3% completed eligible MRIs. While both MED diets reached similar moderate weight (MED: − 2.7%, green-MED: − 3.9%) and waist circumference (MED: − 4.7%, green-MED: − 5.7%) loss, the green-MED dieters doubled the VAT loss (HDG: − 4.2%, MED: − 6.0%, green-MED: − 14.1%; p < 0.05, independent of age, sex, waist circumference, or weight loss). Higher dietary consumption of green tea, walnuts, and Wolffia globosa; lower red meat intake; higher total plasma polyphenols (mainly hippuric acid), and elevated urine urolithin A polyphenol were significantly related to greater VAT loss (p < 0.05, multivariate models).
A green-MED diet, enriched with plant-based polyphenols and lower in red/processed meat, may be a potent intervention to promote visceral adiposity regression.