Sugar Worsens Antibiotic Damage to Gut Bacteria

A study of hospitalized blood cancer patients links sugar intake to reduced beneficial gut bacteria during antibiotic treatment.

Updated on Nov. 1, 2026 in Nutrition

Photograph of a clear glass flask of cloudy amber liquid beside a single sugar cube on a pale wooden bench under soft window light. — A study of 173 hospitalized blood cancer patients in Nature found sugar intake worsened antibiotic-driven loss of beneficial gut bacteria. AI Illustration. Upload story photo >

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Would you cut back on sweets while taking antibiotics?

A study published in the journal Nature found that sugar intake worsens the reduction of beneficial gut bacteria caused by antibiotics. Researchers also observed blooms of Enterococcus faecium, a bacterium linked to hard-to-treat infections, in patients with a sugary diet combined with antibiotics.

Why it matters

Antibiotics kill helpful gut bacteria along with the bacteria causing infection, and diet may influence how much of that damage occurs. The findings suggest dietary choices during antibiotic treatment could affect gut health.

The evidence comes from microbiome tracking of 173 hospitalized blood cancer patients who logged more than 9,000 meals, showing a more than 20% drop in helpful bacterial variety per 100 grams of sugar eaten in the 48 hours before treatment. The extraction does not state how the findings would apply to people outside blood cancer care.

The players

NYU Langone Health

A New York-based academic medical center that served as the lead research institution for the study.

City of Hope

A cancer research and treatment center in California that co-led the research.

Memorial Sloan Kettering Cancer Center

A New York cancer center that co-led the research.

The details

Researchers tracked every food item eaten by 173 hospitalized cancer patients and measured changes in their gut microbiome. Mouse experiments run concurrently confirmed the Enterococcus faecium result seen in patients.

48 hours before treatment: sugar consumption window measured against microbiome changes.

Health Landscape

The findings extend a line of microbiome research from major cancer centers on how antibiotic-treated patients lose gut bacterial diversity. Adding diet as a variable points toward nutrition as a modifiable factor in that recovery.

The study suggests that reducing sweets during and after antibiotic treatment could help limit gut damage. The extraction notes this could also benefit people without cancer who take antibiotics.

The takeaway

Limiting sweets while taking antibiotics may help reduce damage to the beneficial bacteria in your gut. Talk with your care team before changing your diet during treatment.