Can Sugar Change How Antibiotics Affect the Gut?

Antibiotics can be important medicines for treating bacterial infections, but they can also disturb the community of microorganisms living in the gut. A new study published in Nature explored whether the foods people eat during antibiotic treatment could influence the extent of this microbiome disruption.

Researchers examined detailed dietary and microbiome data from 173 people hospitalized for hematopoietic cell transplantation, a treatment that often involves intensive chemotherapy and antibiotic exposure. The team tracked 9,419 meals and analyzed more than 1,000 stool samples, with 158 participants providing paired microbiome samples that could be followed over time. This detailed approach allowed researchers to examine food intake alongside changes in gut bacteria.

The researchers found that consuming more sweets and simple sugars during antibiotic exposure was associated with greater disruption of the gut microbiome. Higher intake was linked with lower alpha diversity, a measure that reflects the variety of microorganisms within an individual’s gut community. The researchers also observed greater expansion of Enterococcus, a group of bacteria that can act as a pathobiont when the normal microbial balance is disturbed.

The human findings were supported by experiments in mice. When mice received antibiotics along with sucrose, Enterococcus expansion became larger and lasted longer than with antibiotics alone. These experiments provide biological clues about how sugar and antibiotics might interact, but they do not establish the same effect in all people.

The study has important limitations. The human portion was observational, so it cannot prove that sugar directly caused microbiome changes. Participants were undergoing intensive cancer treatment, meaning the findings may not apply to otherwise healthy adults taking routine antibiotics. Other factors, including illness, medications, treatment intensity, and overall diet, may also influence the microbiome. The authors say further studies in independent groups and clinical trials are needed.

This study suggests that diet may influence how strongly antibiotics disturb the gut microbiome, particularly in people undergoing intensive medical treatment. It also highlights an important area for future research: whether short-term dietary changes could help maintain microbial diversity during antibiotic use.