Sugar may worsen antibiotic-induced gut dysbiosis

The effect was most apparent with added sugars and formulated nutritional drinks, including sports drinks and nutritional shakes.

By
Andrea Surnit
October 7, 2026
5 min

MDSpire News

At a Glance

Category	Detail
Condition	Antibiotic-associated gut microbiome disruption during allogeneic hematopoietic cell transplantation
Key Mechanisms	In the observational study, higher sweets or sugar intake during broad-spectrum antibiotic exposure was associated with lower microbiome alpha-diversity and greater Enterococcus faecium abundance. In mice, sucrose increased antibiotic-associated enterococcal expansion.
Target Population	Adults undergoing allogeneic hematopoietic cell transplantation; experimental findings were also assessed in mice.
Care Setting	Single-center inpatient transplantation care during antibiotic treatment; the human findings are observational and do not establish that reducing sugar improves clinical outcomes.

Key Highlights

The prospective observational study included 173 adult transplant recipients; the primary Bayesian analysis included 1,009 stool samples from 158 patients.
Broad-spectrum antibiotic exposure in the preceding 2 days was associated with lower microbiome alpha-diversity.
Higher sweets intake during broad-spectrum antibiotic exposure was associated with a greater decrease in alpha-diversity; each additional 100 g of sugar was associated with a further 21% decrease in mean alpha-diversity.
Higher sweets intake after broad-spectrum antibiotic exposure was linked to increased Enterococcus faecium abundance.
In mice, sucrose increased enterococcal expansion after biapenem, but not in mice without antibiotic exposure; prospective studies are needed to assess effects of sugar reduction.

Guideline-Based Recommendations

Diagnosis

The study assessed longitudinal stool microbiome samples, including alpha-diversity and microbial composition.

Management

The authors state that prospective studies are needed to determine whether reducing sugar during antibiotic treatment preserves the microbiome or improves clinical outcomes.

Monitoring & Follow-up

Researchers examined dietary intake during the 2 days before stool collection alongside microbiome measures and antibiotic exposure.

Risks

The human study was observational and single-center; illness severity, incomplete capture of food consumed outside the hospital, and treatment-related symptoms may have influenced associations.
The mortality association may partly reflect reduced overall food intake rather than sugar consumption itself.

Patient & Prescribing Data

173 adults undergoing allogeneic hematopoietic cell transplantation at Memorial Sloan Kettering Cancer Center from 2017 to 2022; all received at least one antibiotic during dietary monitoring, and 138 transitioned to broad-spectrum antibiotics.

Broad-spectrum antibiotics were commonly initiated for neutropenic fever or bloodstream infection. Higher sweets or sugar intake during broad-spectrum antibiotic exposure was associated with greater microbiome disruption; the study does not establish a treatment recommendation.

Clinical Best Practices

Interpret the reported diet–microbiome associations as observational rather than causal evidence in transplant recipients.
Consider the study's population and exposure context: prophylactic fluoroquinolone use was nearly universal, and the reported interaction concerned escalation to broad-spectrum antibiotics.
Do not infer that sugar reduction improves microbiome or clinical outcomes; the authors call for prospective studies.