Study links high sugar consumption to increased gut microbiome damage during antibiotic treatment

Study links sugar consumption to antibiotic damage

A clinical study published in Nature on 30 September 2026 shows that consuming high amounts of sugar while taking antibiotics accelerates damage to the intestinal microbiome. Researchers coordinated by Memorial Sloan Kettering Cancer Center in New York, alongside New York University and City of Hope, examined how specific dietary components influence bacterial diversity during medical treatment. Antibiotics are essential for combating infections, but broad-spectrum varieties also eliminate beneficial gut bacteria that regulate immune function and aid digestion. The study found that patients consuming sweet foods and beverages experienced a measurable decline in bacterial variety. Co-author Jonas Schluter noted the value of identifying preventative measures during therapy.

Our study suggests that modifying diet during and after antibiotic use, particularly by reducing sweet consumption, could help in that regard.

Detailed dietary tracking of transplant patients

The investigation analyzed the dietary intake and biological samples of 173 hospitalized blood cancer patients undergoing allogeneic hematopoietic stem cell or bone marrow transplantation. Before transplantation, these individuals received intensive chemotherapy and, in some cases, radiation therapy, leaving their immune systems vulnerable. Every participant received at least one antibiotic during their hospital stay to prevent or treat infections, with 80% receiving broad-spectrum antibiotics. The research team recorded 9,419 meals and tracked individual food items using nutritional data provided by hospital food services alongside patient reports. To measure the biological effects of this intake, researchers gathered and sequenced 1,009 stool samples from 158 of the participants.

Proliferation of resistant bacteria and clinical risks

Analysis of the nutritional and biological datasets revealed a direct quantitative relationship between sugar intake and microbial disruption. For every 100 grams of sugar consumed during the 48 hours prior to antibiotic exposure, researchers recorded an additional 21% reduction in alpha diversity, the metric measuring the variety of bacterial species in the gut. The combination of high-sugar intake and broad-spectrum antibiotics also increased the likelihood of harmful bacterial strains multiplying in the digestive tract. Among these opportunistic pathogens was Enterococcus faecium, a species known to cause infections that are difficult to treat with standard antimicrobial therapies. Co-author Marcel van den Brink described the consistency of these findings across statistical evaluations.

Regardless of how we analyzed the data, the same signal kept appearing.

Implications for oncology care and future trials

In hematologic cancer patients, preservation of the gut microbiome correlates directly with medical recovery and overall survival. Severe microbial disruption in this population is associated with higher total mortality rates and a greater susceptibility to severe hospital-acquired infections. The researchers emphasized that dietary intervention represents a controllable variable that clinical teams could manage during intensive antimicrobial regimens. Designing targeted dietary protocols could help shield vulnerable patients from collateral pharmaceutical damage without compromising antibiotic efficacy. Co-author Jonathan Peled outlined the next phase of research needed to translate these observational findings into bedside practice.

An important next step will be to design clinical trials to verify whether short-term dietary changes can improve clinical outcomes for patients.