Beneficial effects of the probiotics and synbiotics supplementation on anthropometric indices and body composition in adults: A systematic review and meta‐analysis

Summary Studies have suggested that probiotics and synbiotics can improve body weight and composition. However, randomized controlled trials (RCTs) demonstrated mixed results. Hence, we performed a systematic review and meta‐analysis to evaluate the effectiveness of probiotics and synbiotics on body weight and composition in adults. We searched PubMed/Medline, Ovid/Medline, Scopus, ISI Web of Science, and Cochrane library up to April 2023 using related keywords. We included all RCTs investigating the effectiveness of probiotics and/or synbiotics supplementation on anthropometric indices and body composition among adults. Random‐effects models were applied for performing meta‐analyses. In addition, we conducted subgroup analyses and meta‐regression to explore the non‐linear and linear relationship between the length of follow‐up and the changes in each outcome. We included a total of 200 trials with 12,603 participants in the present meta‐analysis. Probiotics or synbiotics intake led to a significant decrease in body weight (weighted mean difference [WMD]: −0.91 kg; 95% CI: −1.08, −0.75; p < 0.001), body mass index (BMI) (WMD: −0.28 kg/m 2 ; 95% CI: −0.36, −0.21; p < 0.001), waist circumference (WC) (WMD: −1.14 cm; 95% CI: −1.42, −0.87; p < 0.001), waist‐to‐hip ratio (WHR) (WMD: −0.01; 95% CI: −0.01, −0.00; p < 0.001), fat mass (FM) (WMD: −0.92 kg; 95% CI: −1.05, −0.79; p < 0.001), and percentage of body fat (%BF) (WMD: −0.68%; 95% CI: −0.94, −0.42; p < 0.001) compared to controls. There was no difference in fat‐free mass (FFM) and lean body mass (LBM). Subgroup analyses indicated that probiotics or synbiotics administered as food or supplement resulted in significant changes in anthropometric indices and body composition. However, compared to controls, FM and %BF values were only reduced after probiotic consumption. Our results showed that probiotics or synbiotics have beneficial effects on body weight, central obesity, and body composition in adults and could be useful as an add on to weight loss products and medications.