# In 173 transplant patients, 100 g of extra sugar linked to 24.1% lower gut diversity on antibiotics

- Published: 2026-11-07 16:47 UTC
- Section: Life & Health › Medicine
- Tags: gut microbiome and antibiotics, sugar intake and microbiome diversity, allogeneic stem cell transplantation, broad-spectrum antibiotics, Enterococcus faecium, alpha diversity of gut bacteria, sucrose and enterococci in mice, Dai et al. Nature 2026, NYU Grossman Jonas Schluter
- URL: https://realtech.media/news/rt-3eefd16c36ac55e34e8b414b_in_173_transplant/

**A Nature study of stem cell transplant patients links sugar intake during broad-spectrum antibiotics to lower gut bacterial diversity; experiments in mice showed a similar effect.**

![In 173 transplant patients, 100 g of extra sugar linked to 24.1% lower gut diversity on antibiotics](https://realtech.media/media/2026/11/1742216bd991f785.webp)
*ad-hoc-news.de*

A study by Dai et al. published in Nature on 30 September 2026 indicates that a sugar-rich diet may amplify the adverse effects of antibiotic treatment on the human gut microbiome, according to ad-hoc-news.de [1]. The authors analysed data from 173 adult patients with blood cancer who underwent allogeneic stem cell transplantation between 2017 and 2022 [1].

## Study design and microbiome results

The team evaluated 9,419 meals comprising 40,702 individual food items, along with 1,009 stool samples from 158 patients. For each patient, 8 to 128 meals were documented, from twelve days before to 49 days after transplantation. In total, 138 of the 173 patients (80%) received broad-spectrum antibiotics [1].

Under broad-spectrum antibiotics, the alpha diversity of gut bacteria fell by 24.1% for every additional 100 g of sugar consumed (95% confidence interval: 7.7 to 38.1). In a supplementary macronutrient analysis, the decline was 20.6% per 100 g of sugar (95% confidence interval: 2 to 35.6) [1]. At the same time, Enterococcus faecium, a potentially harmful bacterium associated with bloodstream infections, expanded more strongly [1].

Among patients whose sugar intake was above the median, the risk of death rose by 12% for each additional day of broad-spectrum antibiotics (hazard ratio 1.12; 95% confidence interval: 1.01 to 1.23) [1].

## Mouse experiments and expert caveats

Supplementary experiments in healthy mice supported the clinical observations. Sugar alone or antibiotics alone did not impair the microbiome to the same degree, whereas combined administration of antibiotics and sucrose led to a massive proliferation of enterococci. Sucrose increased enterococcal expansion 16.3-fold on day 3 and 33.4-fold on day 6. Without antibiotics, sucrose had no such effect [1].

Co-author Jonas Schluter of NYU Grossman said that a targeted reduction of sugar during and after antibiotic therapy could be helpful. The researchers noted that the current data are not sufficient for a general clinical recommendation [1].

Other specialists urged caution. Malena García Arredondo, head of MGA Healthy Digest, said the results from severely ill cancer patients cannot be transferred directly to the general population. She added that microbiome recovery often takes weeks to months and that bacterial resistance genes may also change [1].

Nina Kisseleva, head of the pharmacy department at the Physics and Mathematics Institute of the Pirogov University Hospital, said that sugar does not reduce the efficacy of antibiotics themselves. In her view, relevant risks arise mainly with long-term broad-spectrum therapy combined with excessive sugar intake. For courses of five to 14 days in healthy people with moderate sweet consumption, serious consequences are hardly to be expected. Simple carbohydrates that are not fully absorbed in the small intestine reach the colon, where they can promote bacteria such as Proteobacteria and favour nonspecific inflammation [1].

## Sources

1. [ad-hoc-news.de](https://www.ad-hoc-news.de/wissenschaft/darmmikrobiom-unter-antibiotika-100-gramm-zucker-senken-vielfalt-um-24-1-prozent/70474969)

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Source: RealTech, realtech.media — https://realtech.media/news/rt-3eefd16c36ac55e34e8b414b_in_173_transplant/