A diet rich in cysteine. an amino acid found in meat, dairy, legumes and nuts, may help the gut heal itself. That’s the finding of new MIT research showing that cysteine activates an immune pathway that stimulates intestinal stem cells to regenerate damaged tissue.
The study, published in Nature, was conducted in mice but could have important implications for people undergoing cancer treatments such as radiation or chemotherapy, which often injure the lining of the intestine.
“The study suggests that if we give these patients a cysteine-rich diet or cysteine supplementation, perhaps we can dampen some of the chemotherapy or radiation-induced injury,” said senior author Omer Yilmaz, MD, PhD, director of the MIT Stem Cell Initiative.
Researchers tested diets enriched with 20 different amino acids, the building blocks of protein, and found that cysteine had the strongest effect on intestinal stem cell regeneration. They discovered that when intestinal cells absorb cysteine, it sets off a chain reaction: immune cells called CD8 T cells proliferate and begin producing IL-22, a cytokine known to boost stem cell activity and repair the intestinal lining.
“What’s really exciting here is that feeding mice a cysteine-rich diet leads to the expansion of an immune cell population that we typically don’t associate with IL-22 production and the regulation of intestinal stemness,” Yilmaz said.
In the study, cysteine-rich diets helped repair radiation-induced gut damage in mice, and unpublished work suggests a similar effect after chemotherapy exposure. While the body can produce cysteine from another amino acid (methionine), dietary cysteine delivers higher concentrations directly to the small intestine, where most protein absorption occurs.
The research builds on growing evidence that individual nutrients can shape tissue repair, not just overall dietary patterns. Still, the findings are early: more studies are needed to determine whether cysteine supplementation could aid human patients or support broader gut health.
For now, the takeaway is that the foods we eat may influence gut resilience in ways scientists are only beginning to understand and amino acids like cysteine could one day help support healing when the gut is under stress.
This research was funded in part by the National Institutes of Health, the V Foundation, the Kathy and Curt Marble Cancer Research Award, the Koch Institute–Dana-Farber/Harvard Cancer Center Bridge Project, the American Federation for Aging Research, the MIT Stem Cell Initiative and the Koch Institute Support (core) Grant from the National Cancer Institute.