Puberulic acid produced by blue mold is the cause of kidney problems suffered by consumers of Kobayashi Pharmaceutical’s beni kōji (red yeast rice) supplements, the health ministry said Wednesday.

The finding came at the end of the ministry's monthslong probe into the supplements, which sparked a health crisis in Japan and abroad among people who took them.

While the ministry had been aware of puberulic acid as a possible cause of the kidney problems, the detection of two unknown chemical compounds kept it from making that finding conclusive.