Nadja B Kristensen and Oluf Pedersen
Accumulating evidence has pointed towards a role of the gut microbiota in the pathogenesis of obesity. Also, the gut microbiota is a dynamic and modifiable community offering itself as a target for therapeutic interventions potentially improving host health. This review gives an overview on effects of clinically controlled interventions with probiotics on body weight regulation in overweight or obese individuals free of co-morbidities. Literature search was performed through PubMed with the criteria 1) healthy overweight/obese adults without comorbidities as study population, 2) probiotics as intervention without limits regarding dose or duration of intervention 3) healthy overweight/obese adults receiving placebo as controls, 4) body weight-related variables as the primary outcome and 5) randomized controlled trial as the study design. Methodological quality of the included studies was assessed using the Jadad score. Seven studies from five different countries met the inclusion criteria. Three studies reported improvements in body weight-related variables after probiotic supplementation compared to that in the controls, whereas four did not find such improvements. Overall, the methodological quality of the studies was limited and ranged from three to five based on the Jadad score. In conclusion, this review failed to identify convincing evidence of a robust effect of interventions with probiotics on body weight regulation in overweight or obese individuals free of co-morbidities. Large high quality randomized controlled trials in well-phenotyped study participants on regulated and to some extent standardized diets with mixtures of probiotics known to have master-switch roles in the gut microbiota composition and function of healthy lean individuals are needed to examine the effects of probiotics on body weight in greater detail.