Fasting helps prepare intestinal cells to respond more quickly and effectively after injury, almost like training the cells with an emergency preparedness plan,
Helen Piwnica-Worms said.
A 24-hour fast helps prepare the intestines to recover from radiation damage by relying on a specific gut bacterium.
New preclinical research from The University of Texas MD Anderson Cancer Center details how fasting and beneficial microbes activate natural tissue repair mechanisms. Published in the Proceedings of the National Academy of Sciences, the study was co-led by Piwnica-Worms, a professor of Experimental Radiation Oncology, and Kunal Rai, a professor of Genomic Medicine.
This study helps explain how that plan is organized and identifies a key bacterium involved in coordinating the response,
Piwnica-Worms said. The findings could eventually lead to new ways to protect healthy tissue during cancer treatment.
Radiation therapy treats cancers in the abdomen, including pancreatic, colorectal, and gynecologic cancers. While radiation destroys cancer cells, it also harms nearby healthy tissue.
The small intestine is particularly vulnerable because its delicate lining is sensitive to radiation exposure. When this protective lining breaks down, patients experience nausea, diarrhea, and infections.
Severe injuries can cause life-threatening complications and restrict the amount of radiation doctors can safely administer. Previous research from the Piwnica-Worms Laboratory showed that fasting before radiation exposure helped intestines recover afterward.
Researchers found that 24 hours of fasting increased the abundance of a beneficial bacterium called Akkermansia muciniphila, or AKK, in the small intestine. This microbe produces propionate, a substance that triggers cellular changes to help cells regenerate following radiation damage.
Propionate modifies proteins known as histones, which serve as structures around which DNA is packaged inside cells. Small chemical markers added to histones influence which genes become active without changing the underlying DNA sequence.
When the intestines face subsequent radiation exposure, these prepared cells expand and help rebuild the damaged lining. Without AKK, fasting no longer produced the same regenerative benefits, and the protective response returned only when the bacterium was restored alongside fasting.
The research remains preclinical, and additional studies are needed to determine if the same protective mechanism operates in humans. Researchers are also interested in whether this pathway can protect other rapidly dividing tissues, such as bone marrow.
Fasting is not always practical for cancer patients, and this work supports several other potential ways to enhance recovery after treatment,
Rai said. Whether through dietary interventions, targeted microbes or their metabolites, the goal is to help repair healthy tissue more effectively while patients receive the cancer therapies they need.
The research received funding from the National Cancer Institute within the National Institutes of Health and the Cancer Prevention and Research Institute of Texas.
No, the study demonstrated that fasting alone is not sufficient to produce the full protective effect. The beneficial gut bacterium Akkermansia muciniphila must be present alongside fasting to activate the tissue repair mechanisms.
The study was funded by the National Cancer Institute, part of the National Institutes of Health, and the Cancer Prevention and Research Institute of Texas.
Radiation therapy used to treat abdominal cancers, including pancreatic, colorectal, and gynecologic cancers, frequently puts the sensitive lining of the small intestine at risk of damage.
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