This academic article introduces a systems-level framework to quantify the amount of fermentation products harvested from the human gut microbiota. The research integrates bacterial metabolism, host physiology, and metagenomic data to provide consistent estimates of these metabolic fluxes. A key finding is that for Western diets, bacteria contribute a relatively small percentage (2%-5%) to human energy demand, a revision of previous estimates. The study further reveals that diet is the primary determinant of the total fermentation product harvest, with microbiota composition having a greater impact on the types of products rather than the overall quantity. The authors also highlight significant differences in microbiota-supplied energy between humans and mice, emphasizing the need for careful consideration when translating findings from mouse models to human health.

References:

• Arnoldini M, Sharma R, Moresi C, et al. Quantifying the varying harvest of fermentation products from the human gut microbiota[J]. Cell, 2025.