Taking antibiotics? Sugar may be making the damage worse

The team emphasized that sugar may act as a fuel source for harmful bacteria

A new study from NYU Langone Health reveals that consuming higher amounts of sugar while taking antibiotics can worsen harm to the gut microbiome. The research, published in October 2026, found that increased sugar intake during antibiotic treatment was associated with greater disruption of beneficial gut bacteria and promoted the growth of potentially harmful microbes. Scientists observed these effects in both laboratory models and human data, suggesting a direct link between dietary sugar and microbiome imbalance during antibiotic therapy. The study examined how sugar influences microbial communities in the gut when antibiotics are present. Researchers noted that antibiotics already reduce microbial diversity, but adding high sugar levels appeared to exacerbate this effect by creating conditions favorable to opportunistic pathogens. One key finding was that certain bacteria linked to inflammation and digestive issues proliferated more rapidly in high-sugar environments, even as helpful species struggled to recover.

The team emphasized that sugar may act as a fuel source for harmful bacteria, undermining the body’s efforts to restore balance after antibiotic use. How sugar fuels harmful bacteria during antibiotic treatment Laboratory tests showed that when sugar was introduced alongside common antibiotics, strains such as Escherichia coli and Clostridioides difficile exhibited increased growth rates compared to low-sugar conditions. These bacteria are known to cause gastrointestinal distress and, in some cases, serious infections. Researchers explained that while antibiotics target a broad range of bacteria, sugar selectively supports those capable of rapid fermentation, giving them a competitive edge. This imbalance may prolong recovery time and increase susceptibility to secondary infections after antibiotic courses end. Can reducing sugar intake protect the gut during antibiotics? Participants who limited sugar consumption during antibiotic treatment showed faster restoration of microbial diversity in follow-up tests.

Although the study did not establish a strict dietary guideline

Although the study did not establish a strict dietary guideline, researchers suggested that minimizing added sugars—such as those in sodas, desserts, and processed snacks—could help mitigate negative effects. They noted that natural sugars from whole fruits appeared less problematic, likely due to accompanying fiber and nutrients that slow absorption. The findings highlight the importance of considering diet alongside medication when aiming to preserve gut health. Frequently Asked Questions Does this mean I should avoid all sugar while on antibiotics? Not necessarily. The study focused on added sugars, not naturally occurring sugars in whole foods like fruits or vegetables. Moderation and choosing complex carbohydrates over refined sugars are advised. How long after antibiotics should I watch my sugar intake? Researchers recommend being mindful of sugar consumption during the entire antibiotic course and for at least one to two weeks afterward, as microbiome recovery can take time.

Are probiotics helpful in this context? While not directly tested in this study, prior research suggests probiotics may support microbiome recovery, though their effectiveness varies by strain and individual factors.