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Taking probiotics before radiation therapy can protect the gut from damage
Last reviewed: 01.07.2025
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Scientists at Washington University in St. Louis have shown that taking probiotic supplements before radiation therapy can protect the intestines from damage - at least in mice.
A new study suggests that taking probiotics may also help cancer patients avoid developing intestinal injury, a common problem in patients treated with radiation therapy. The study is published in the online journal Gut.
Radiation therapy is often used to treat prostate, cervical, bladder, endometrial, and other abdominal cancers. But this therapy kills both cancer cells and healthy cells, causing severe diarrhea due to damage to the intestinal lining.
"For many patients, this means stopping radiation therapy or reducing the radiation dose so the intestine can rebuild its epithelium," says Nicholas W. Costrini, a professor of gastroenterology at the University of Washington. "Probiotics can protect the small intestinal lining from this damage."
Stenson was looking for ways to repair and protect healthy tissue from radiation. This study found that the probiotic bacteria Lactobacillus rhamnosus GG (LGG) protected the lining of the small intestine in mice exposed to radiation.
"The lining of the intestine is made up of only one layer of cells," Stenson says. "This layer of epithelial cells separates the body from what's inside the intestine. If the epithelium is destroyed by radiation, bacteria that normally live in the intestine can enter the bloodstream and cause sepsis."
The researchers found that the probiotic was only effective if given to the mice before irradiation. If the mice received the probiotic after the intestinal lining had been damaged, the LGGs were unable to repair it.
"In earlier studies, patients typically took probiotics after diarrhea developed, when the intestinal cells were already damaged," says first author Matthew A. Chorba, MD, assistant professor of medicine in the division of gastroenterology. "Our study suggests that we should give probiotics before symptoms develop or even before radiation therapy, because then we're preventing damage rather than alleviating symptoms of damage that's already occurred."
The researchers sought to evaluate the mechanisms by which LGG may have protective effects. "There have been studies in the past that have looked at the effects of probiotics on diarrhea, but most of these studies have not looked at the mechanisms by which probiotics prevent the development of intestinal epithelial damage," Stenson says.
Stenson and colleagues showed that prostaglandins and cyclooxygenase-2 (COX-2) inhibitors can protect cells in the small intestine by preventing programmed cell death (apoptosis) that occurs in response to radiation.
Future research by the scientists will focus on isolating the radioprotective factor produced by probiotics. By isolating and developing therapeutic doses of this substance, the researchers will be able to harness the benefits of probiotics without using live bacteria.
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