24-hour fast primes the gut to recover from radiation, study finds
Researchers at the MD Anderson Cancer Center in the US found that a 24-hour fast boosts the gut bacterium Akkermansia muciniphila and prepares intestinal cells to regenerate after radiation. The work is preclinical, and its results still need testing in humans.
Scientists at The University of Texas MD Anderson Cancer Center in the United States have found that a 24-hour fast can prepare cells of the small intestine to regenerate after radiation damage, but only when a specific gut bacterium is present. The research is preclinical and was published in the Proceedings of the National Academy of Sciences. In the longer term, the finding could help protect healthy tissue during cancer treatment and make radiation therapy safer.
Why radiation harms the intestines
Radiation therapy is widely used for cancers of the abdomen, including pancreatic, colorectal and gynecologic cancers. It destroys cancer cells but can also injure nearby healthy tissue. The lining of the small intestine is especially sensitive. When it is damaged, patients may suffer nausea, diarrhea and infections, and severe injuries can lead to life-threatening complications. These risks can also limit the radiation dose doctors can safely give.
Earlier preclinical work from the same laboratory showed that fasting before radiation helped the intestines recover, but the reason was not fully understood.
How the mechanism works
The researchers found that 24 hours of fasting increased the amount of the bacterium Akkermansia muciniphila (AKK) in the small intestine. The microbe produces a substance called propionate, which, together with other metabolic changes caused by fasting, modifies histones, the proteins around which DNA is packaged in cells. These changes make parts of DNA more accessible and allow genes involved in tissue regeneration to switch on. Fasting increases the number of intestinal cells carrying these repair programs, and after radiation they can expand and rebuild the damaged lining.
When the team removed the bacterium, fasting no longer gave the same benefit. The protective response returned only when the bacterium was restored together with fasting.
What comes next
Helen Piwnica-Worms, professor of Experimental Radiation Oncology and co-leader of the study, compared the effect to training cells with an emergency preparedness plan. Co-leader Kunal Rai, professor of Genomic Medicine, noted that fasting is not always practical for cancer patients, so dietary approaches, targeted microbes or their metabolites are being considered as alternatives. Studies must first show whether the mechanism works in humans. Researchers are also interested in other rapidly dividing tissues, such as bone marrow.
The work was funded by the US National Cancer Institute and the Cancer Prevention and Research Institute of Texas.
