Antibiotics are some of the most prescribed drugs around the world – and while they’re handy for fighting a whole host of bacterial infections, anyone who’s been on them will know they can also wreak havoc on gut health.
On a very simple level, the medication targets bacteria in the body to kill off the bad stuff – unfortunately it can also get rid of the good stuff, too.
“The extent to which antibiotics affect the gut depends on several factors,” Dr Megan Rossi, a gut health scientist at King’s College London, previously told HuffPost UK, suggesting that the type of antibiotic matters (broad-spectrum ones, for example, affect a wider range of bacteria in the gut), as does the dose (prolonged or repeated courses can have a greater cumulative impact).
And if you eat sugar-filled snacks while you’re taking them, it may well worsen the harm caused to the bacteria in the gut, a new study suggests.
What did the new study find?
The microbiome can typically resist a buildup of nasty pathogens when it’s functioning normally, but antibiotics can reduce the natural species diversity in the gut and make it more vulnerable to disease.
Researchers tracked every food item in 9,419 meals eaten by 173 hospitalised cancer patients and then measured their gut microbiome changes.
They discovered an additional 21% reduction in ‘alpha diversity’ (a measure of the variety of helpful bacterial species present in the gut) for every 100g of sugar consumed in the 48 hours before treatment.
The study also showed how the combination of a sugary diet and antibiotic treatment caused “blooms” of the bacterial species Enterococcus faecium, which has been linked to hard-to-treat infections.
Co-senior author Jonas Schluter, assistant professor in the Department of Microbiology at NYU Langone, said: “Our study, which used more than 9,000 recorded meals, suggests that modifying diet during and after antibiotics, specifically by reducing sweets intake, could help with that.”
Another of the study’s co-authors, William Jogia, a PhD student in Dr Schluter’s lab in the Institute for Systems Genetics, suggested that dietary sugars might amplify antibiotic gut disruption “because the potentially harmful bacteria that survive the antibiotics are benefiting from the dietary sugars that they can use to expand”.
He added: “While the findings suggest that reducing simple sugars may limit microbiome injury, whether sugar directly supports Enterococcus, weakens competing bacteria, or acts through another mechanism in patients remains to be seen.”
The research team studied patients with blood cancers because they receive antibiotics frequently and precisely tracking food intake is feasible while they’re in hospital. They recorded patient diets at every meal and collected microbiome samples daily.
Patients with blood cancers who undergo stem cell transplantation are typically in hospital for weeks, during which they receive both chemotherapy and antibiotics. During this time, they show severe damage to their microbiomes and harmful bacterial species like Enterococcus faecium often thrive because the rest of the gut ecosystem has been “destroyed”.
Microbiome injury in these patients is typically linked to worse outcomes, including higher overall mortality and infections, according to Jonathan Peled, co-senior author on the study, who wants to see future clinical trials test whether short-term diet changes can improve clinical outcomes.
