A high-polyphenol, calorie-restricted Mediterranean diet supplemented with green tea and the Mankai strain of duckweed optimized the microbiome for autologous fecal microbiota transplantation, which maintained both weight loss and insulin sensitivity after the diet ended, according to the findings of a novel clinical trial.
Eight months after the diet ended, 17% of individuals in the autologous fecal microbiota transplantation (aFMT) group had regained weight, compared with 50% of those who received oral placebo (P = .02). Gains in weight circumference were 1.89 cm and 5.05 cm, respectively (P = .01), and changes in fasting insulin levels were 1.46 (standard deviation, 3.6 mIU/mL) and 1.64 mIU/mL (standard deviation, 4.7 mIU/mL; P = .04). Notably, aFMT did not achieve these results after weight loss on a typical Mediterranean diet, with or without calorie restriction. “Diet-induced weight loss can be preserved, along with glycemic control, for months after a diet via aFMT capsules. A high-polyphenols, green plant-based or Mankai diet better optimizes the microbiome for an aFMT procedure,” Ehud Rinott, an MD, PhD student at Ben-Gurion University of the Negev in Beer-Sheva, Israel, and his associates wrote in Gastroenterology.
Significant weight regain after dieting is common and undermines cardiometabolic strides. In animal studies, FMT from lean to obese individuals induces both weight loss and metabolic improvements, and limited data point to similar benefits in humans. However, allogenic FMT in humans raises safety concerns and “practical barriers,” Mr. Rinott and his associates noted. Hypothesizing that aFMT of microbiota obtained at nadir weight might prevent postdiet rebounds, they randomly assigned 294 obese or dyslipidemic adults (average age, 52 years) to receive the calorie-restricted “green” Mediterranean diet or a standard Mediterranean diet with or without calorie restrictions for 6 months. At this time, microbiota obtained from fecal samples were frozen in colorless, odorless oral capsules that were considered indistinguishable from placebo capsules. Ninety participants who had lost at least 3.5% of their body weight (average loss, 8.3 kg) were then rerandomized in a double-blinded manner to receive once-daily aFMT or placebo capsules during months 8 through 14.
In all, 96% of participants consumed at least 80% of the capsules, a high rate of compliance. No adverse events from aFMT were reported. Metagenomic sequencing and 16s ribosomal RNA sequencing showed that only the “green” Mediterranean diet induced significant alterations in the gut microbiome during the weight-loss phase. In a complementary study of obese mice, autologous transplantation of microbiota obtained at nadir weight confirmed that adding Mankai during weight loss helped protect against subsequent regain and loss of insulin sensitivity.
All diets in this study emphasized vegetables while reducing sugars, salt, dietary cholesterol, trans and saturated fats, and poultry, and omitting processed and red meats. The “green” and standard calorie-restricted Mediterranean diets both limited calories to 1,500-1,800 per day for men and 1,200-1,400 per day for women (women comprised only 9% of study participants). In these two diets, fats – mainly monounsaturated and polyunsaturated – made up 40% of calories (including 28 g walnuts per day, containing 440 mg polyphenols), while carbohydrates were limited to less than 40 g per day in the first 2 months and then gradually increased to 80 g per day. The green Mediterranean diet added 3-4 cups of green tea daily and a shake containing 100 g of Mankai, which provided another 800 mg of polyphenols. All participants received free gym memberships and were told to exercise throughout the study (aerobic exercise for 45-60 minutes three to four times weekly, and resistance exercise two to three times weekly).
Funders included the Israeli Science Foundation, Israeli Ministry of Health, Israel Ministry of Science and Technology, German Research Foundation, California Walnuts Commission, and others. Mr. Rinott had no conflicts. Three coinvestigators disclosed ties to CoreBiome, Hinoman, and Mybiotics.
SOURCE: Rinott E et al. Gastroenterology. 2020 Aug 25. doi: 10.1053/j.gastro.2020.08.041.