Impact of low and non-calorie sweeteners on the gut microbiota: a review of clinical trials and cross-sectional studies

Use of non-nutritive sweeteners (NNSs) has increased worldwide in the last decades. However, evidence from preclinical studies is showing that sweetener consumption may induce glucose intolerance through changes in the gut microbiota, which raises public health concerns. As studies conducted on humans are lacking, the aim of this review was to gather and summarize the current evidence on the impact of NNSs on the human gut microbiota. Only clinical trials and cross-sectional studies were included in the review. Regarding NNSs, i.e. saccharin, sucralose, aspartame and stevia, only two clinical trials out of five showed significant changes in gut microbiota composition after the intervention protocol. These studies also concluded that saccharin and sucralose impair glycemic tolerance. Three out of the four cross-sectional studies observed an association between NNSs and the microbial composition. All three clinical trials on polyols (i.e. xylitol) showed prebiotic effects on the gut microbiota, but these studies presented multiple limitations (publication date, dosage, duration) that jeopardize their validity. The microbial response to NNSs consumption could be strongly mediated by the gut microbial composition at baseline. Further studies that acknowledge the potential personalized microbial response to NNSs consumption and that include longer intervention protocols, larger cohorts and more realistic sweetener dosage are needed to broaden these findings.