Sugary Diets Worsen Antibiotic Damage to Gut

A study of blood cancer patients links high sugar intake during antibiotic treatment to greater loss of helpful gut bacteria.

Updated on Nov. 1, 2026 in Nutrition

Isometric editorial illustration of a stack of white sugar cubes beside a single amber capsule on a cream base, evoking the sugar-antibiotic gut link. — A study of blood cancer patients links high-sugar diets during antibiotic treatment to greater loss of helpful gut bacteria, published in Nature. AI Illustration. Upload story photo >

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Would you cut back on sweets while taking antibiotics?

A study published in Nature found that a sugary diet during antibiotic treatment is linked to greater disruption of helpful gut bacteria in hospitalized blood cancer patients. Researchers from NYU Langone Health, City of Hope and Memorial Sloan Kettering Cancer Center tracked the diets of 173 patients, relevant to people who take antibiotics and eat a lot of sweets.

Why it matters

Antibiotics kill helpful gut bacteria alongside the bacteria causing infection, and this study suggests diet may influence how much damage occurs. The findings point to a modifiable factor, what people eat while on antibiotics, at a time when gut health and antibiotic-resistant infections are major concerns.

This observational study tracked every food item eaten by 173 hospitalized blood cancer patients across more than 9,000 recorded meals and measured changes in their gut microbiome. Mouse experiments run concurrently confirmed the Enterococcus faecium finding, but the human results apply only to patients with blood cancers.

The players

NYU Langone Health

A New York academic medical center known for its clinical research across cancer, microbiome and infectious disease fields.

City of Hope

A California cancer research and treatment center conducting clinical and translational research on blood cancers.

Memorial Sloan Kettering Cancer Center

A New York cancer center with a longstanding research program in oncology and cancer-related infection.

The details

Antibiotics are a standard treatment for infection, but they do not discriminate between harmful and helpful bacteria in the gut. In this study, a high-sugar diet during antibiotic treatment was associated with a larger loss of beneficial bacterial diversity and with blooms of Enterococcus faecium, a bacterium linked to hard-to-treat infections. Researchers measured this relationship by linking detailed food records to microbiome measurements.

The sugar consumption window measured was the 48 hours before treatment.
The study was published in Nature on November 1, 2026.

Health Landscape

Research into the gut microbiome has grown rapidly since the Human Microbiome Project mapped microbial communities across the body. This study moves that work from description toward identifying modifiable factors, such as diet, that shape how the microbiome responds to treatment.

If you are prescribed antibiotics, it is worth asking your doctor or pharmacist whether dietary changes such as limiting sweets are advisable during and after treatment. People who do not have cancer may still benefit from reducing sugar intake while taking antibiotics, though this is a population-level finding to discuss with a clinician.

The takeaway

Reducing sweets while taking antibiotics may help limit damage to helpful gut bacteria, based on this study of blood cancer patients. Talk with your physician before making dietary changes tied to any medication.