An analysis of data from the DIRECT-PLUS trial is providing new insight into the effects of a modified Mediterranean on visceral adipose tissue among participants in the 18-month weight loss trial.
Results of the study, which assessed the effects of a modified Mediterranean diet characterized by an increased level of polyphenols, found that adherence to the Mediterranean diet reduced visceral fat by 7% and adherence to the healthy diet reduced it by 4.5% compared with the control diet, while the green Mediterranean diet stood apart with a mean reduction in visceral fat of 14%.
"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," said Iris Shai, MD, of Ben-Gurion University of the Negev, Israel and an adjunct professor from the Harvard School of Public Health, in a statement.
Led by Shai and a team of colleagues from Ben-Gurion University and Harvard School of Public Health, the Dietary Intervention Randomized Controlled Trial Polyphenols Unprocessed (DIRECT-PLUS) was launched with the intent of exploring the effects of the green Mediterranean diet, which is a modified version of the Mediterranean diet enriched with an addition 800 mg of daily dietary polyphenols via consumption of 3-4 cups of green tea and 100 grams of duckweed green shake each day.
The trial enrolled 294 participants and randomized them in a 1:1:1 ratio to a healthy diet, a Mediterranean diet, or the green Mediterranean diet. The primary outcome of interest for the trial was difference in visceral adiposity, which was quantified using magnetic resonance imaging (MRI). The cohort had a mean age of 51 years, 88% were men, the mean BMI was 31.2 kg/m2, and 29% had visceral adipose tissue. The trial had a retention rate of 89.8% and 79.3% of participants completed eligible MRIs.
Upon analysis, a similar degree of weight loss was observed with both the Mediterranean and the green Mediterranean diets, with mean body weight reductions of -2.7% and -3.9%, respectively, and mean reductions in waist circumference of -4.7% and -5.7%, respectively. However, a more than doubling in mean reduction of visceral adipose tissue was observed with the green Mediterranean diet (-14.1%) compared to Mediterranean diet (-6.0%) and the healthy diet (-4.2%) (P for trend <.05), with this effect independent of age, sex, waist circumference, or weight loss. Investigators pointed out increased consumption of green tea, walnuts, and Wolffia globosa, lower red meat intake, higher total plasma polyphenols , and elevated urine urolithin A polyphenol were significantly related to greater visceral adipose tissue reductions (P <.05).
"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," added Hila Zelicha, RD, PhD, of the Health and Nutrition Innovative International Research Center at Ben-Gurion University of the Negev, in the aforementioned statement.
This study, “The effect of high-polyphenol Mediterranean diet on visceral adiposity: the DIRECT PLUS randomized controlled trial,” was published in BMC Medicine.