Simple dietary sugars amplify gut microbiome disruptions caused by antibiotics by feeding harmful bacteria and hindering healthy recovery, according to an American study. Researchers found that mice and specific patients who consumed high-sugar diets while taking broad-spectrum antibiotics experienced prolonged and severe gut flora imbalances.
Dietary Sugar Amplifies Antibiotic Gut Disruption
Simple sugars in food act as a modifiable amplifier of microbiome damage induced by antibiotics. Researchers studied patients undergoing allogeneic hematopoietic cell transplantation for leukemia. These hospitalized individuals received chemotherapy followed by broad-spectrum antibiotics to prevent infections. Patients who consumed diets high in sugar showed reduced microbial diversity and a notable expansion of Enterococcus bacteria.
Researchers noted that among patients following a high-sugar diet, the duration of exposure to broad-spectrum antibiotics served as a predictor of mortality risk. However, investigators noted that this increased mortality risk could also partially stem from decreased overall food intake among severely ill patients.
Mouse Experiments Confirm Microbial Shifts
To test whether sugars and antibiotics act in synergy, researchers conducted experiments on mice. The animal trials confirmed that sucrose exacerbated and prolonged the proliferation of endogenous Enterococcus triggered by antibiotics. This expands dietary determinants of microbiome disruption beyond the known role of fiber.
Professor Manuela Santos, an intestinal microbiome specialist at the Research Centre of the Centre hospitalier de l’Université de Montréal, explained that harmful bacteria thrive on sugar, whereas beneficial bacteria prefer fiber. After antibiotics decimate the gut flora, a high-sugar diet naturally favors the multiplication of pathogenic bacteria over beneficial strains.
Microbiome Balance Affects Overall Health
The human intestinal microbiome contains approximately 4,500 different types of bacteria supporting vital bodily functions. An imbalance impacts digestion, body weight, the immune system, and mental health. While the study focused on severely ill transplant patients, Professor Santos suggested that the findings offer intuitive guidance for the general public during antibiotic use.
It makes sense when you take an antibiotic to try to limit the expansion of harmful bacteria by cutting sugar,
Professor Santos stated. She noted that while researchers do not yet know if this applies identically to every antibiotic in every situation, consuming sugary foods clearly hampers microbiome reconstitution. Explaining the mechanism of microbial competition, Professor Santos added: The balance between the two is essential. So there is competition for space and for food. That is why it makes sense that sugar will benefit deleterious bacteria rather than beneficial ones.
The human intestinal microbiome is estimated to be composed of about 4,500 different types of bacteria, all of which contribute to the proper functioning of the body.
Frequently Asked Questions About Sugar and Antibiotics
- Does this study prove that eating sugar ruins any short course of antibiotics?
- No. Professor Santos clarified that the study observed a very specific patient population receiving aggressive treatments for leukemia, meaning the findings cannot yet be universally generalized to all everyday antibiotic prescriptions.
- Which bacteria multiply when combining sugar and antibiotics?
- Researchers observed an expansion of Enterococcus bacteria, which thrive on simple dietary sugars while beneficial microbes starve in the absence of adequate dietary fiber.
- How many types of bacteria make up the human intestinal microbiome?
- The human gut microbiome is estimated to consist of roughly 4,500 different bacterial types that contribute to metabolism, immunity, and overall health.
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