A naturally occurring polyphenol in rice bran has shown the ability to calm overactive intestinal muscles in laboratory tests — a finding that could point toward dietary strategies for managing irritable bowel syndrome. For those interested in evidence-based nutrition, the discovery adds a promising data point to the growing field of food-as-medicine research.
What Happened
Researchers at Toho University’s Faculty of Pharmaceutical Sciences, led by Dr. Keisuke Obara and Professor Yoshio Tanaka, tested ferulic acid — a polyphenol abundant in rice bran — on intestinal smooth muscle tissue from guinea pigs. The compound suppressed contractions triggered by multiple signaling molecules, including acetylcholine, histamine, prostaglandin F2α, and serotonin. The mechanism: ferulic acid blocks voltage-dependent calcium channels, preventing the calcium influx that drives muscle contraction. Importantly, the effect was concentration-dependent and fully reversible, meaning the muscle returned to normal once the compound was removed. The results were published in the Journal of Pharmacological Sciences, as reported by ScienceDaily.
What This Means for Nutrition
The findings are preliminary — the effective concentrations in the lab exceeded typical blood levels achieved through normal dietary intake. However, the researchers note that concentrations in the intestinal wall following direct consumption of rice bran or ferulic acid supplements may be considerably higher. If future clinical trials confirm the effect in humans, it could support a low-cost, food-based approach to managing diarrhea-dominant IBS and inflammatory bowel disease. One caveat: by reducing gut motility, ferulic acid could worsen constipation-predominant IBS, so context matters. Whole-food sources of ferulic acid include rice bran, wheat bran, oats, and tomatoes — foods already recognised for their broader fiber and antioxidant benefits.