Researchers from NYU Langone Health, City of Hope, and Memorial Sloan Kettering tracked 9,419 meals consumed by 173 hospitalized cancer patients to measure changes in their intestinal health. Data indicated a 21% reduction in alpha diversity—the variety of helpful bacterial species—for every 100 grams of sugar consumed in the 48 hours preceding treatment. This loss of diversity leaves the gut vulnerable, as the remaining environment often becomes dominated by harmful pathogens like Enterococcus faecium.

Experiments conducted in mice corroborated these findings, showing that the combination of the antibiotic biapenem and dietary sucrose triggered a 16.3-fold increase in Enterococcus populations within three days, climbing to a 33.4-fold higher burden by day six. Investigators suggest that harmful bacteria likely exploit these dietary sugars to expand rapidly once antibiotics have eliminated their natural competitors. While further clinical trials are required to confirm if short-term dietary adjustments can improve patient recovery, the team emphasizes that moderating sugar intake during and after antibiotic therapy may serve as a simple, effective strategy to limit collateral damage to the microbiome.