ReviewLow calorie sweeteners and gut microbiota

- The low calorie sweetener, NHDC, enhances the population abundance of gut Lactobacillaceae.
- NHDC reduces lag phase of Lactobacillus growth and enhances expression of its sugar transporters.
- A bacterial plasma membrane receptor is required for the sweetener-induced proliferation of Lactobacillus.
- Fecal specimens are poor representatives of the microbial content of the large intestine.

Studies dating back to 1980s, using bacterial cultures, have reported associations between low calorie sweeteners (LCS) and alterations in bacterial composition, raising the potential that LCS might exert effects on the host via interactions with gut microbiota. However, the results of a few recent studies carried out in this area have produced controversies. There is evidence that human fecal samples, used in most human microbiome studies, may provide a poor representation of microbial contents of the proximal intestine. Furthermore, fecal short chain fatty acid levels do not exemplify the amount of short chain fatty acids produced in the intestine. Short chain fatty acids are largely absorbed in the intestine by a tightly regulated mechanism. Here we present an exemplar study showing that the determination of the molecular mechanism(s) underlying the precise mode of action of a LCS on gut microbiota allows for rational and scientifically-based recommendations.