Reducing the amount of sugar during antibiotic therapies avoids the collapse of the “good” bacteria in the intestine and prevents aggressive strains from taking over.
Intestinal problems related to antibiotic treatments are perhaps not inevitable: reducing the amount of sugar consumed during these treatments could protect the intestinal microbiome.
They explain it in a research published on Natureresearchers from the City of Hope, an important private US research centre: in a five-year experiment on patients being treated for blood cancers, a diet with less sugar protected the diversity of intestinal bacteria and contributed to the success of oncological treatments.
Defenses eliminated
Good diversity of gut bacteria supports immune defenses and is associated with better clinical outcomes for patients undergoing cancer treatment.
In the analysis above Naturescientists followed 173 patients in a very delicate phase due to the risk of contracting infections: a hospital stay of a few weeks to receive intensive chemotherapy (and in some cases also radiotherapy) to prepare for an allogeneic hematopoietic stem cell transplant, an infusion of stem cells that give rise to all the blood cells coming from healthy donors.
Patients about to receive this therapy are prepped with chemo and radiotherapy to create space for healthy cells to take root and eliminate immune cells that could cause rejection. To avoid the risk of infections, each patient had to undergo antibiotic therapy, and 80% took broad-spectrum antibiotics, which target different types of bacteria.
Food diaries
At each meal brought to the room, the patients wrote down which foods they had eaten and in what quantity. For each patient, faithful data were collected, and not just self-reported, on a number of meals between 8 and 128, for a period between 12 days before and 49 days after the transplant. At the same time, tests were carried out on over 1000 stool samples to monitor the composition and changes of the microbiome.
The researchers then used statistical models to find connections between nutrition and microbiome health. “Patients who consumed more sweets while taking antibiotics were more likely to suffer a loss of microbiome diversity, as aggressive microbes displaced other bacterial strains,” explains Marcel van den Brink, President of the City of Hope in Los Angeles.
A prevalent population
Among the organisms that took over was theEnterococcusa bacterium that normally lives in the intestine but which, especially in hospital contexts, can take over by colonizing areas other than the intestine and triggering serious infections.
In people undergoing a hematopoietic stem cell transplant, it can lead to an increased risk of blood infections, graft-versus-host disease (an immune reaction of the donor’s cells against the recipient’s tissues), and other very serious complications.
Overall, the combination of high-sugar foods and broad-spectrum antibiotics led to a 24 percent decline in gut bacterial diversity for every additional pound of sugar consumed (roughly the amount of sugar in a 15-ounce packet of breakfast biscuits). And it is precisely the “biodiversity” of bacteria that prevents one aggressive species from prevailing over others.
Studies on mice then confirmed that it was precisely the sugar-rich diet that favored the excessive growth of Enterococci. Mice that ate a high-sugar diet but did not take antibiotics maintained normal bacterial diversity.
Protective choices
The study encourages those involved in the nutrition of cancer patients to support therapies with a balanced diet, not too rich in sugar. This is especially true if you consider that: «Many of the foods and drinks that we recommend to hospitalized patients, such as nutritional shakes, smoothies and isotonic drinks, are rich in sugars» explain the authors.
One hypothesis is that the same indications could protect the gut microbiome even in patients not being treated for cancer who take antibiotics in response to a bacterial infection. But this hasn’t yet been proven, and “it would be premature to recommend that everyone taking antibiotics avoid sugar,” says den Brink.
«On the other hand, we have no concrete evidence that probiotics help preserve or restore the diversity of the microbiota and many people choose to take them anyway. There’s no harm in limiting sugar in your diet, and it’s an easy thing to try.”
