# Red yeast rice (Monascus purpureus)

**Monascus purpureus*; Chinese *hong qu**

**Known today as.** Rice fermented with a red mould.

Kind: Fungus

> **Caution.** Acts as a statin; not to be combined with statin drugs.

## What was it used for?

A food coloring, wine starter, and medicine in China for the blood and digestion.

## What does modern science say?

It contains monacolin K, the same molecule as the drug lovastatin (first drawn from the mould *Aspergillus terreus*), and lowers cholesterol; supplements vary in strength and can contain a kidney toxin.

## Pharmacognosy and toxicology

- **monacolin K**: identical to the drug lovastatin
- **citrinin**: a nephrotoxic contaminant in some products

**Mechanism.** Monacolin K inhibits HMG-CoA reductase, the enzyme of cholesterol synthesis: it is lovastatin, which was first isolated from a *Monascus* mould by Endo in 1979.

**Dose.** Supplements vary a hundredfold in monacolin K, and carry the muscle and liver effects of a statin unlabelled.

**Standing.** Products with a drug’s worth of monacolin K are ruled unapproved drugs in the United States; the European Union limits them to under 3 mg a day since 2022.

## What lore surrounds it?

Listed in Li Shizhen’s *Compendium of Materia Medica* (1578).

## Sources

- Li Shizhen, *Bencao gangmu* (1578).
- Endo, A. (1979). “Monacolin K, a new hypocholesterolemic agent produced by a *Monascus* species.” *Journal of Antibiotics* 32.
- Gordon, R. Y., et al. (2010). “Marked variability of monacolin levels in commercial red yeast rice products.” *Archives of Internal Medicine* 170.

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*Red yeast rice.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-09-25. The Thinking Press. https://thethinkingpress.org/materia-medica/red-yeast-rice

Historical description, not medical advice.