A compound produced after walnut consumption was linked to healthier colon tissue
A recent study published in Cancer Prevention Research examined the cancer-protective effects of walnuts, focusing on the role of urolithin A —a compound produced in the gut when certain polyphenols found in walnuts are metabolized by the microbiome. Urolithin A has been associated with anti-inflammatory and potential anti-cancer properties.
This observational clinical study included 39 participants aged 50-65 years with colonic polyps, a common precursor to colorectal cancer. Participants were instructed to eat 56 grams of walnuts daily for 3 weeks.
Researchers found that walnut consumption led to increased urinary levels of urolithin A, though production varied among individuals. Participants with higher urolithin A levels had lower concentrations of several inflammatory markers in the blood. Spatial imaging of polyp tissues revealed altered cell cluster patterns associated with urolithin A, including reduced expression of two markers linked to tumor progression.
The authors concluded that walnut-derived urolithin A may support colonic health by reducing systemic and tissue-level inflammation.
The California Walnut Commission provided funding for this study.
Moussa, M. R., Fan, N., Birk, J., Provatas, A. A., Mehta, P., Hatano, Y., Chun, O. K., Darooghegi Mofrad, M., Lotfi, A., Aksenov, A., Motta, V. N., Zenali, M., Vaziri, H., Grady, J. J., Nakanishi, M., & Rosenberg, D. W. (2025). Systemic Inflammation and the Inflammatory Context of the Colonic Microenvironment Are Improved by Urolithin A. Cancer Prevention Research (Philadelphia, Pa.), 18(4), 235–250.