Radiation is a front-line treatment for abdominal cancers such as pancreatic, colorectal and gynecologic tumors, but the same beams that target a tumor also damage the small intestine, whose lining is made of rapidly dividing cells. The injury can cause nausea, diarrhea and infection, and in severe cases it limits how much radiation a patient can safely receive. Researchers at MD Anderson had already seen that fasting before treatment helped the intestine recover — but the mechanism was unclear.
A new study published in the Proceedings of the National Academy of Sciences (PNAS) points to a surprising partner: a gut bacterium called Akkermansia muciniphila, often shortened to AKK. The team found that fasting for 24 hours increased AKK's abundance in the small intestine. That matters because AKK produces propionate, a small molecule released when microbes break down nutrients. Propionate, working alongside other metabolic shifts triggered by fasting, modifies histones — the proteins that spool DNA inside cells — nudging intestinal cells into a state primed for regeneration after injury.
The lead authors describe fasting as giving cells "an emergency preparedness plan" so they respond faster and more effectively once damage occurs. Crucially, the work is still preclinical and has not been tested in patients, so it does not yet change medical advice. But by naming the specific microbe and molecule involved, the findings suggest a future where a probiotic or metabolite could be used to shield healthy tissue during cancer therapy — without asking patients to fast.
Knowledge takeaway: MD Anderson researchers (PNAS, July 2026) found that a 24-hour fast raises levels of the gut bacterium Akkermansia muciniphila (AKK) in the small intestine; AKK releases propionate, which joins fasting-driven metabolic changes to modify histones and prepare intestinal cells for regeneration after radiation injury; the small intestine is especially vulnerable to radiation used against abdominal cancers, and damage can cap the safe treatment dose; the result is preclinical (not yet tested in people), but it identifies a concrete bacterium-and-molecule route that could one day protect healthy tissue during cancer therapy.