A fermented brown rice powder for ulcerative colitis: in a trial that waited 20 years to be published, symptoms didn't improve, though an inflammation marker may have

Fibre has a good reputation in gut disease, but ulcerative colitis, an inflammation of the lining of the large bowel, is one place where the evidence is still patchy. A trial published in JGH Open on 5 October 2026 tested a Japanese health food built around fibre: brown rice and rice bran fermented with Aspergillus oryzae, the koji mould behind sake, miso and soy sauce. The powder, sold in Japan as FBRA, is about a quarter fibre by weight. Mice given it were protected from a chemically induced colitis, but it had never been tried in patients.

The trial itself is old. Researchers recruited 56 adults with ulcerative colitis at Osaka Chuo Hospital between October 2006 and April 2007, and 52 started on the study food. None were on steroids or immune-suppressing drugs, and most were taking the standard anti-inflammatory 5-ASA. Half took the fermented rice powder, building up over two weeks to six 3.5 g sachets a day (21 g); the other half took granules of lightly roasted wheat flour that looked the same and had almost no fibre. Neither the patients nor their doctors knew which was which. After 14 weeks, a three-month break and 14 weeks on the other product, the groups swapped, but the main comparison was the first 14 weeks.

On the question the trial was built to answer, the powder did nothing measurable. The clinical activity index, a 21-point score covering diarrhoea, blood in the stool, pain and general well-being, improved in 6 of 26 people on fermented rice (23%) and 5 of 26 on the dummy (19%), and got worse in more than half of each group. After the swap, fewer people improved on the rice powder than on the dummy. The hopeful signal was in the blood: high-sensitivity C-reactive protein, a marker of inflammation, fell in 17 of 26 on the rice powder (65%) against 10 of 26 on the dummy (38%). That gap is just short of statistical significance, and only clears the line when the six people who stopped taking the powder are left out.

There are good reasons to hold that signal lightly. 'Improved' here meant any fall at all, however small, so the trial counts people rather than measuring how far their inflammation dropped, and it reports no colonoscopy results after treatment. Six of the 26 starting on the rice powder asked to stop in the first 14 weeks, five of them because of nausea or a feeling of fullness, against two on the dummy, both because their colitis got worse. The study was small, ran at one hospital and is published almost 20 years after the last patient joined. Genmaikoso, the Sapporo company that makes the powder, supplied both products and paid for the data centre, while the authors declare no conflicts of interest. The authors call it exploratory and ask for a larger trial, which is the right reading: a hint worth testing, not a reason to add a sachet to treatment.