Effects of a Low-Fat Vegan Diet on Gut Microbiota in Overweight Individuals and Relationships with Body Weight, Body Composition, and Insulin Sensitivity. A Randomized Clinical Trial.
Study Goal
The researchers aimed to test the effect of a low-fat vegan diet on gut microbiota and its association with weight, body composition, and insulin resistance in overweight individuals.
Results Summary
The vegan diet led to significant weight loss, reduced fat mass and visceral fat, improved insulin sensitivity, and favorable changes in gut microbiota, including increased Faecalibacterium prausnitzii and a smaller reduction in Bacteroides fragilis, which correlated with metabolic improvements.
Population
Overweight men and women
Effective Dosage
Not specified
Duration
16 weeks
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
low-fat vegan diet | decrease | body weight | overweight men and women | -5.9 kg [95% CI, -7.0 to -4.9 kg] | decreased | #1 |
low-fat vegan diet | decrease | fat mass | overweight men and women | -3.9 kg [95% CI, -4.6 to -3.1 kg] | reduction | #2 |
low-fat vegan diet | decrease | visceral fat | overweight men and women | -240 cm3 [95% CI, -345 to -135 kg] | reduction | #3 |
low-fat vegan diet | increase | PREDIM (predicted clamp-derived insulin sensitivity index) | overweight men and women | +0.83 [95% CI, +0.48 to +1.2] | increased | #4 |
low-fat vegan diet | increase | relative abundance of Faecalibacterium prausnitzii | overweight men and women | +5.1% [95% CI, +2.4 to +7.9%] | increased | #5 |
low-fat vegan diet | increase | relative abundance of Bacteroides fragilis | overweight men and women | +18.9% [95% CI, +14.2 to +23.7%] | positive treatment effect | #6 |
low-fat vegan diet | neutral | gut microbiota | overweight adults | - | induced significant changes | #7 |
Diet modulates gut microbiota and plays an important role in human health. The aim of this study was to test the effect of a low-fat vegan diet on gut microbiota and its association with weight, body composition, and insulin resistance in overweight men and women. We enrolled 168 participants and randomly assigned them to a vegan (n = 84) or a control group (n = 84) for 16 weeks. Of these, 115 returned all gut microbiome samples. Gut microbiota composition was assessed using uBiome Explorer™ kits. Body composition was measured using dual energy X-ray absorptiometry. Insulin sensitivity was quantified with the predicted clamp-derived insulin sensitivity index from a standard meal test. Repeated measure ANOVA was used for statistical analysis. Body weight decreased in the vegan group (treatment effect -5.9 kg [95% CI, -7.0 to -4.9 kg]; p < 0.001), mainly due to a reduction in fat mass (-3.9 kg [95% CI, -4.6 to -3.1 kg]; p < 0.001) and in visceral fat (-240 cm3 [95% CI, -345 to -135 kg]; p < 0.001). PREDIcted M, insulin sensitivity index (PREDIM) increased in the vegan group (treatment effect +0.83 [95% CI, +0.48 to +1.2]; p < 0.001). The relative abundance of Faecalibacterium prausnitzii increased in the vegan group (+5.1% [95% CI, +2.4 to +7.9%]; p < 0.001) and correlated negatively with changes in weight (r = -0.24; p = 0.01), fat mass (r = -0.22; p = 0.02), and visceral fat (r = -0.20; p = 0.03). The relative abundance of Bacteroides fragilis decreased in both groups, but less in the vegan group, making the treatment effect positive (+18.9% [95% CI, +14.2 to +23.7%]; p < 0.001), which correlated negatively with changes in weight (r = -0.44; p < 0.001), fat mass (r = -0.43; p < 0.001), and visceral fat (r = -0.28; p = 0.003) and positively with PREDIM (r = 0.36; p < 0.001), so a smaller reduction in Bacteroides fragilis was associated with a greater loss of body weight, fat mass, visceral fat, and a greater increase in insulin sensitivity. A low-fat vegan diet induced significant changes in gut microbiota, which were related to changes in weight, body composition, and insulin sensitivity in overweight adults, suggesting a potential use in clinical practice.