Background: This study tested the effect of a 16-week plant-based diet on gut microbiota composition, body weight, body composition, and insulin resistance in overweight adults with no history of diabetes.
Methods: Participants (n=148) were randomized to follow a low-fat vegan diet (n=73) or to make no diet changes (n=75) for 16 weeks. At baseline and 16 weeks, gut microbiota composition was assessed, using uBiome kits. Dual energy X-ray absorptiometry was used to measure body composition. PREDIM index was used to assess insulin sensitivity. Repeated measure ANOVA was used for statistical analysis.
Results: Body weight was reduced significantly in the vegan group (treatment effect -5.8 kg [95% CI, -6.9 to -4.7 kg]; p<0.001), particularly due to a reduction in fat mass (treatment effect -3.9 kg [95% CI, -4.6 to -3.1 kg]; p<0.001) and in visceral fat (treatment effect -172 cm3 [95% CI, -308 to -37 kg]; p=0.01). PREDIM increased significantly (p<0.001) in the vegan group (treatment effect +0.88 [95% CI, +0.5 to +1.2]; p<0.001). The relative abundance of Faecalibacterium prausnitzii increased in the vegan group (treatment effect +4.8% [95% CI, +1.97 to +7.58%]; p=0.001). Relative changes in Faecalibacterium prausnitzii correlated negatively with changes in body weight (r=-0.26; p=0.008), fat mass (r=-0.26; p=0.008), and visceral fat (r=-0.25; p=0.01). The relative abundance of Bacteoides fragilis increased in the vegan group (treatment effect +19.5% [95% CI, +14.7 to +24.3%]; p<0.001). Relative changes in Bacteroides Fragilis correlated negatively with changes in body weight (r=-0.48; p<0.001), fat mass (r=-0.48; p<0.001), visceral fat (r=-0.24; p=0.02), and positively with changes in PREDIM (r=0.36; p=0.0004).
Conclusions: A 16-week low-fat vegan dietary intervention induced changes in gut microbiota that were related to changes in weight, body composition and insulin sensitivity in overweight adults.
H. Kahleova: None. A. Tura: None. N. Barnard: None.
Physicians Committee for Responsible Medicine
