A survey by an academic society has found that nearly 200 people in Japan had kidney function tests after taking supplements containing the "beni-koji" ingredient, or red yeast fermented rice.
The supplements made by Osaka-based drugmaker Kobayashi Pharmaceutical are linked to numerous reports of kidney problems.
The Japanese Society of Nephrology asked member doctors if their patients developed kidney disorders after taking the firm's three products that have been recalled.
The group on Tuesday released the results that are dated to the end of April. The survey showed that 189 people received kidney function tests after taking the products.
It quoted the doctors as saying that the tests did not indicate irregularities for about 15 people. But they said many showed symptoms including kidney function disorders, loss of appetite, fatigue and abnormal urine.
The society said blood and urine tests indicated that many of the patients were likely suffering from Fanconi syndrome, which causes declining function of tiny tubes in the kidneys.
Out of 94 patients who had their kidney tissues tested, 43.5 percent had inflamed tubes and 28.3 percent had tubes with necrosis, or dead body tissue.
The survey said kidney functions have improved in about three-quarters of the patients after they stopped taking the supplements. But it said that 20 percent of the patients received steroid treatments, and that 10 percent are still on medication.
The doctors said seven people needed kidney dialysis. But they said at least one of them had been suffering from kidney disease before taking the supplement.
The vice president of the Japanese Society of Nephrology, Isaka Yoshitaka, said many patients experienced relatively minor symptoms, but that about 10 percent need continued treatment.
Isaka said he recommends people who have taken the supplements to receive a check-up test just to be sure.