Sugar may reduce gut bacterial diversity during antibiotics

Blood cancer patients who ate sugary foods during antibiotic treatment lost more gut bacterial diversity than those on antibiotics alone. For each extra 100 grams of sugar eaten in the two days before sampling, diversity fell 24 percent. The same eating pattern was linked to blooms of Enterococcus, bacteria that can resist drugs and are tied to hard-to-treat infections. Sugar may add to the damage antibiotics do to gut microbes, the study suggests.

Study design

The team followed 173 people hospitalized at a treatment center for blood-forming stem cell transplants. They logged more than 9,000 meals. Because hospital meals were standardized, the researchers could measure nutrients down to the gram. They then compared those amounts with bacterial diversity in stool samples. This avoided relying on self-reported diet records, which are common in microbiome studies.

Scientists also fed mice either regular or sucrose-rich diets, then gave them a single dose of antibiotics. The sugary diet increased Enterococcus after drug exposure. Sarah Berry, a nutrition scientist at King's College London who was not involved in the study, said reducing sugar intake could be another way for patients to support their gut microbiome during antibiotic treatment. More research is needed to determine whether the findings apply to anyone taking these drugs.