Eating sugary foods while taking antibiotics appears to worsen the damage the drugs do to gut bacteria, according to a study published in Nature on 30 September 2026. Researchers at City of Hope, Memorial Sloan Kettering Cancer Center and NYU Grossman School of Medicine tracked 9,419 meals and more than 1,000 stool samples from 173 hospitalised patients with blood cancer undergoing an allogeneic haematopoietic cell transplant, around 80% of whom were given broad-spectrum antibiotics. Among the 158 patients with paired microbiome samples, City of Hope's release put the finding at a 24% drop in bacterial diversity for every additional 100 grams of sweets eaten during antibiotic exposure, alongside greater expansion of Enterococcus, a bacterium the authors class as a pathobiont. Mouse experiments showed the same pattern, with a high-sucrose diet plus antibiotics producing Enterococcus overgrowth while the sugar-heavy diet alone did not reduce diversity. City of Hope lists US National Institutes of Health grants as the funding.
Who the patients were
These were not healthy volunteers. Allogeneic transplant patients receive conditioning chemotherapy and heavy antibiotic cover, so their gut bacteria are already badly disrupted before diet is considered, which is part of why a dietary signal was measurable at all. The dietary records were unusually precise for nutrition research, logged from hospital meals in real time rather than recalled later. The human analysis remains observational, and the authors call for clinical trials. Marcel van den Brink, one of the senior authors, said in the City of Hope release: "It's premature to recommend everyone taking antibiotics avoid sugar."
What this means for your supplement routine
Very little. The paper measured what hospitalised transplant patients ate and how their gut bacteria responded. It did not test any supplement, and it does not support a claim that any product shields a microbiome during a course of antibiotics. Everything in Perqen's catalogue is regulated as food, not as a treatment, and nothing in this research changes that. Questions about diet during a course of prescribed antibiotics belong with the prescribing clinician.
How Perqen members save
Perqen is a membership retailer stocking established supplement brands sourced through an authorised EU distributor, with member pricing at £4.99 a month or £29.99 a year. Membership affects the price you pay and nothing else.
This article reports published news and research and is for information only. Food supplements are not a substitute for a varied diet or medical care, and no product mentioned is intended to diagnose, treat, cure or prevent any disease. Speak to your GP or pharmacist before changing what you take, especially if you are pregnant, breastfeeding, or taking prescribed medicines.