Kobayashi red yeast supplement contamination caused deaths and a national recall

In March 2024, Kobayashi Pharmaceutical asked consumers to stop using three red yeast rice (beni-koji) supplements marketed to help lower cholesterol, after receiving reports of kidney problems. The company said its own tests found an unintended component in some red yeast rice raw material, and Japan's Ministry of Health, Labour and Welfare (MHLW) later ordered the products disposed of under the Food Sanitation Act.

Health officials linked the supplements to at least five deaths and hundreds of hospitalisations. An MHLW investigation with the National Institute of Health Sciences concluded in September 2024 that the fermentation stage at a Kobayashi factory had been contaminated by the blue mould Penicillium adametzioides, which produced puberulic acid, a compound that can cause renal dysfunction. The same raw material had also been sold to around 52 direct customers and reached an estimated 173 downstream companies.

The recall spread beyond Kobayashi's own brands and triggered a wider safety review of functional foods. Functional food sales in Japan fell by roughly 10% in the weeks after the recall, and regulators surveyed about 1,700 manufacturers. The case exposed the lighter manufacturing oversight applied to foods with functional claims compared with pharmaceuticals.