Recent study explores gut microbe amount and its impact on the body

Researchers from a recently published study in the journal, Cell, sought to investigate how much gut bacteria were used and regenerated in a day.^1,2 Researchers selected 22 bacterial species by focusing on their “relative abundances in a typical healthy human gut microbiota.”²

To research the gut microbiome, data was collected from participants diets, along with their daily stool production. Materials collected were then analyzed where researchers measured the amount of fermentation products produced by the bacteria in order to restore the bacterial mass.¹

“Our findings provide a detailed picture of how intensively the gut microbiota and the host exchange substances,” says Markus Arnoldini, first author of the study.¹ “This knowledge is crucial for understanding exactly how the gut microbiome influences our health.”

Data showed that the nutrients from the participants diets helped spur microbiota growth with carbon joining in fermentation products that are then absorbed back into the host. Study authors mentioned that this “covers 2%–5% of human energy demand for Western diets and up to 10% for non-Western diets. Microbiota composition has little impact on the total harvest but determines the amount of specific fermentation products. This consistent quantification of metabolic fluxes by our analysis framework is crucial to elucidate the gut microbiota’s mechanistic functions in health and disease.”¹ Research additionally showed that by changing diet, held more significance on its impact regarding the amount of fermentation products.

“The precise quantification of these molecular signals forms an important basis for future research,” explains Markus Arnoldini.¹ “Our methods could help to investigate changes in the daily dose of bacterial fermentation products in specific disease patterns such as colon cancer or chronic inflammatory bowel disease more precisely.”

“Although our experimental data implicitly account for cross-feeding of acetate, further work on the quantitative role of cross-feeding on lactate is needed to better understand the molecular composition of the fermentation product harvest, especially in microbiomes where the relative abundance of microbiota members performing this function is high,” the study’s authors commented.² “Our present analysis is a starting point for such efforts since fermentation is the major source of energy on which other microbial processes in the gut depend.”

References

1. Gut microbes: How many molecules influence our body? https://hest.ethz.ch/en/news/news-and-events/2025/07/gut-microbes-how-many-molecules-influence-our-body.html (accessed Aug 4, 2025).
2. Arnoldini, M.; Sharma, R.; Moresi, C.; Chure, G.; Chabbey, J.; Slack, E.; Cremer, J. Quantifying the varying harvest of fermentation products from the human gut microbiota https://www.cell.com/cell/fulltext/S0092-8674(25)00794-9?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0092867425007949%3Fshowall%3Dtrue (accessed Aug 4, 2025).