Red yeast rice is what is referred to as a kōji in Japanese, meaning "grain or bean overgrown with a mold culture", a food preparation tradition going back to ca.

[2][3] A modern-era use as a dietary supplement developed in the late 1970s after researchers were isolating lovastatin from Aspergillus and monacolins from Monascus, the latter being the same fungus used to make red yeast rice.

English language articles favoring Chinese literature sources prefer the translation "red yeast rice".

[2] It is also traditionally used in the production of several types of Chinese huangjiu (Shaoxing jiu), and Japanese sake (akaisake), imparting a reddish color to these wines.

Medicinal use of red yeast rice is described in the Chinese pharmacopoeia Ben Cao Gang Mu compiled by Li Shizhen ca.

[2][13] One reference provided the Li Shizhen health claims as a quotation "...the effect of promoting the circulation of blood and releasing stasis, invigorating the spleen, and eliminating [in]digestion.

"[3] In the late 1970s, researchers in the United States and Japan were isolating lovastatin from Aspergillus and monacolins from Monascus, the latter being the same fungus used to make red yeast rice (RYR) when cultured under carefully controlled conditions.

Lovastatin and other prescription statin drugs inhibit cholesterol synthesis by blocking action of the enzyme HMG-CoA reductase.

[16] In a press release the FDA "...is warning consumers to not buy or eat red yeast rice products... may contain an unauthorized drug that could be harmful to health."

The rationale for "harmful to health" was that consumers might not understand that the dangers of monacolin-containing red yeast rice are the same as those of prescription statin drugs.

Close to 5,000 post-heart attack patients were enrolled for an average of 4.5 years to receive either a placebo or a RYR product named Xuezhikang (血脂康).

[17][25] Commercial products also have highly variable amounts of monacolins[17] and rarely declare this content on the label, making risk assessment difficult.

Continuous monitoring of dietary supplements should be promoted to finally characterize their risk profile, thus supporting regulatory bodies for appropriate actions.

The reason given was case study reports of severe adverse reactions to products containing monacolins at amounts as low as 3 mg/day.

[30] In March 2024, the Japanese Ministry of Health ordered stores to remove three RYR dietary supplements (Benikoji ColesteHelp, NaishiHelp Plus Cholesterol and Natto-kinase Sarasara Tsubu) produced by Kobayashi Pharmaceutical after reports of thousands made ill.[31] Over a hundred people between the ages of 40 to 80 were hospitalized, and five had died as of 29 March[update], with four of them from kidney problems.

[31] Some analysts have placed the blame on industry deregulation, intended to boost economic growth by facilitating the approval of health products.