Red yeast rice 紅麹

In Japan

• In 2024, kidney damage occurred one after another with Foods with Function Claims and other products that used Kobayashi Pharmaceutical's red yeast rice. Puberulic acid, derived from blue mold, was found in the raw material, and damage to the kidneys (proximal tubules) was confirmed.
• According to MHLW working group materials (July 30, 2025), as of June 30, 2025, Kobayashi Pharmaceutical had received reports of 413 deaths, of which 141 involved people who had taken (or were suspected of having taken) red yeast rice products.
• In response, the Foods with Function Claims system was revised: reporting of health harm diagnosed by a physician became mandatory (effective September 1, 2024), and GMP (good manufacturing practice) became a requirement for tablet and capsule products (from September 1, 2026).

In the EU: the register of health claims

EU claim withdrawn

• The claim "Monacolin K from red yeast rice contributes to the maintenance of normal blood cholesterol" was once authorised but was later withdrawn (2024 amendment of the regulation).
• In 2018, EFSA concluded that it could not identify an intake of monacolins from red yeast rice that is safe.

In the EU, only health claims whose evidence has been assessed by the European Food Safety Authority (EFSA) and authorised by the European Commission may be used on food. “Not authorised” means the evidence for that claim was not established under EU standards — not that the ingredient is dangerous.

What the US NIH says

• Products high in monacolin K may lower cholesterol, but the US FDA regards products with that amount as unapproved new drugs that cannot be legally sold.
• Muscle, kidney, and liver side effects and drug interactions similar to those of statins can occur. Some products have been contaminated with citrinin, which is toxic to the kidneys.

Sources: MHLW eJIM "Red yeast rice", NCCIH