The effects of three non-caloric sweeteners on the gut microbiota composition and activity of individuals with overweight or obesity in an in vitro model of the colon.

The consumption of sweeteners and sweetness enhancers (S&SE) has increased over the past decades. Recent literature indicates controversies regarding the safety of sweetener consumption, concerning effects on gut microbial composition and related adverse alterations in metabolic health. In the present study, we aimed to determine the effects of three non-caloric sweeteners (saccharin, sucralose, and stevia rebaudioside A) on the composition and functionality of the gut microbiota using a validated in vitro model of the human colon. Over a 72 h intervention period, pooled microbiota from individuals with overweight was cultivated in a simulated ileal efflux medium (SIEM) with a standard carbohydrate mix (control) or one of the three sweeteners. Gut microbial composition was determined in lumen samples, and organic acid concentrations were measured in lumen and dialysis samples. There were no significant differences in alpha and beta diversities between S&SE or SIEM over time. Both saccharin and sucralose increased the abundance of potential SCFA-producing bacterial genera, such as Oscillospiraceae_003, undetermined genus belonging to Ruminococcaceae family, Barnesiella, Butyricicoccus, and Coprobacter, compared to the control condition, but changes were not significant after multiple testing adjustment. However, the highest SCFA production was observed in SIEM in comparision with the S&SE tested (208.0 mmol for SIEM vs. 134.9 mmol for sucralose, 124.8 mmol for rebaudioside A, and 115.5 mmol for saccharin). Although SCFA levels were lower in gut microbiota exposed to S&SE than under SIEM, SCFA production increased over time across all S&SE products. Among the S&SE, sucralose yielded the highest concentrations of acetate (50.4 mmol), short-chain fatty acids (134.9 mmol) and branched-chain fatty acids (11.5 mmol). There are distinct effects of non-caloric S&SE on gut microbiota composition and function. Future research should determine whether these effects can be translated to in vivo conditions and investigate the link to metabolic health.