Japan Researchers Uncover Mechanism behind Beni Koji Hazard

Tokyo, March 5 (Jiji Press)–A Japanese research team has uncovered a part of the mechanism by which a substance found in Kobayashi Pharmaceutical Co.’s supplements containing “beni koji,” or red fermented rice, triggered kidney damage, it was learned Thursday. Although it had been known that puberulic acid derived from blue mold was behind the high-profile health scare involving the supplements, it was unclear how the substance damaged kidneys. A research team from the Institute of Science Tokyo, led by Assistant Professor Yutaro Mori, found that puberulic acid reduced the function of mitochondria in kidney cells, causing tubular cell necrosis and weakening renal function. The team administered the problematic supplements and puberulic acid to mice, and found that all mice showed signs of renal function deterioration as well as renal tubule damage and fibrosis. An analysis of kidney gene activity showed that the functions of genes related to mitochondria were weakened, hindering mitochondria from making energy for cells. Similar phenomena were observed in tests using cells made from human kidneys and organoids, or 3D miniatures of organs produced in vitro. It is believed that the decline in mitochondrial function leads to a decrease in adenosine triphosphate, the source of energy for cells, and an increase in reactive oxygen species, triggering cell death. “We have discovered an important path linking the supplement to kidney damage,” Mori said. “In the future, this may help prognosis assessments and treatment of patients suffering from aftereffects.” Kobayashi Pharmaceutical announced in March 2024 that it had received reports of health damage related to the supplements. The Osaka city government, which compiled a report on the matter based on the food sanitation law, said that during the cultivation of beni koji, puberulic acid may have entered and proliferated due to cracks in the cultivation drums. END [Copyright The Jiji Press, Ltd.]