Foods high in sugar may potentially increase the harmful effects of broad-spectrum antibiotics on the gut microbiome. This is suggested by a study with cancer patients published in the journal “Nature”.
So should people generally avoid sugar while taking antibiotics? “It is premature to recommend that everyone taking antibiotics avoid sugar,” said co-author Marcel van den Brink from the US cancer research and treatment center City of Hope.
"On the other hand, we don't have clear evidence that probiotics help maintain or restore microbiome diversity - and many people choose to take them anyway. There's no harm in limiting sugar consumption in the diet, and it's easy to try."
Antibiotics are used to treat infections, but they also destroy beneficial bacteria in the gut on a large scale, allowing harmful microbes to proliferate excessively. The research team now examined patients who received a stem cell transplant because of blood cancer.
You will often receive antibiotics, and it is also possible to accurately record your food intake during your hospital stay. Jonathan Peled's group from Memorial Sloan Kettering Cancer Center in New York recorded 9,419 meals from 173 cancer patients.
Stool samples from 158 patients were also analyzed for changes in the intestinal flora. All patients received at least one antibiotic during the recording period. 80 percent were temporarily given broad-spectrum antibiotics, which have the strongest effect on the microbiome because they target many different types of bacteria.
The researchers compared the diet in the two days before each stool sample with the composition of the intestinal microbiome. The so-called alpha diversity, a measure of the diversity of existing bacterial species, was used for the evaluation.
The combination of high-sugar foods and broad-spectrum antibiotics appeared to increase the damage to the microbiome: For every 100 grams of additional food from the “sweets and high-sugar foods” category, the bacterial diversity decreased by around 24 percent, according to the model estimate. What is meant is the dry weight of the food, not 100 grams of pure sugar.
Growth aid for resistant intestinal germs
“No matter how we analyzed the data, the same clear signal kept appearing,” van den Brink explained. “Patients who consumed more sweets during antibiotic treatment were more likely to experience loss of microbiome diversity as aggressive microbes crowded out other bacterial strains.”
This was particularly true for the amount of enterococci, especially Enterococcus faecium. This bacteria can cause difficult-to-treat infections in very sick people. The researchers then tested their observations in experiments with mice. There, sucrose – the chemical name for table sugar – increased the proliferation of enterococci after treatment with the antibiotic biapenem.
The bacterial load was 16.3 times higher on the third day and 33.4 times higher on the sixth day than in animals that received the antibiotic but no additional sugar. Sucrose alone did not significantly change the amount of enterococci.
The researchers believe it is possible that sugar makes it easier for the bacteria that remain after antibiotic treatment to grow. Which mechanism actually works is still an open question.
The study does not prove that a low-sugar diet prevents infections or improves chances of survival. A particularly seriously ill group of patients was examined during intensive treatment. The results cannot easily be transferred to all people taking antibiotics.
In addition, the study observed the diet and did not specifically intervene in it. It is now necessary to specifically investigate whether a temporary change in diet actually improves the microbiome and the course of the disease, it was said.
