Red Yeast Rice | Supplementopedia

Overview

Red yeast rice (RYR) is a fermented product of Monascus purpureus grown on rice.
The fermentation produces a suite of naturally occurring statin‑like compounds, most notably monacolin K, which is chemically identical to lovastatin.
RYR is chiefly used as a dietary supplement for managing blood lipids, especially low‑density‑lipoprotein (LDL) cholesterol.

Clinical trials and meta‑analyses consistently show that RYR lowers LDL‑C by 15‑25 % and modestly raises HDL‑C (3–6 %) when taken for 8–12 weeks (e.g., Li et al., J Clin Lipidol 2021).
The LDL‑lowering effect translates into a modest reduction in cardiovascular risk markers, such as C‑reactive protein and arterial stiffness.
RYR also modestly improves triglyceride levels.
RYR may modestly blunt post‑prandial glucose spikes, likely via improved insulin sensitivity (Samaroo et al., Am J Clin Nutr 2022).
No robust evidence supports direct cognitive or muscular benefits beyond the lipid‑mediated cardiovascular protection.

The primary active component, monacolin K (lovastatin), is a competitive inhibitor of HMG‑CoA reductase.
HMG‑CoA reductase is the rate‑limiting enzyme in the mevalonate pathway that produces cholesterol.
By binding the enzyme’s active site, monacolin K reduces conversion of HMG‑CoA to mevalonate, decreasing hepatic cholesterol synthesis.
Reduced intracellular cholesterol up‑regulates LDL‑receptor expression on hepatocytes, enhancing clearance of circulating LDL particles.
In addition to monacolin K, RYR contains other monacolins (e.g., monacolin J) and flavonoids.
These additional compounds may provide antioxidant and anti‑inflammatory actions, further modulating endothelial function and plaque stability.

Standardized RYR extracts delivering 5–10 mg monacolin K per capsule are most common.
Clinical trials typically use 1–3 g of RYR powder daily (equivalent to 5–10 mg monacolin K).
Dosage is often divided into two doses taken with meals to improve absorption and minimize gastrointestinal upset.
For modest LDL‑C reduction, 1 g twice daily (≈10 mg monacolin K) is the most frequently studied regimen.
Higher doses (up to 4 g/day) have been used in hyper‑cholesterolemic patients under medical supervision.
Timing with meals is recommended because post‑prandial bile release enhances absorption of the lipophilic monacolin K.

RYR is generally well tolerated at ≤10 mg monacolin K per day.
Reported adverse events include mild gastrointestinal discomfort, headache, and, rarely, myopathy or elevated liver enzymes—effects similar to low‑dose lovastatin.
Contra‑indicated in pregnancy, lactation, and for individuals with active liver disease (ALT/AST >3× ULN) or known statin hypersensitivity.
Interactions occur with CYP3A4 inhibitors (e.g., clarithromycin, itraconazole) and with other lipid‑lowering agents (e.g., fibrates) that increase myopathy risk.
Patients on anticoagulants (warfarin) may experience enhanced anticoagulation due to altered vitamin K metabolism; monitoring is advised.

The principal statin‑like molecule in RYR is monacolin K (lovastatin).
Its molecular formula is C₂₄H₃₆O₅, with a molecular weight of 404.54 g mol⁻¹.
IUPAC name: (3S,5R,6R,7E,10R,13R,14R,15S)-7,13‑dimethyl‑3‑[2‑(1‑oxor‑3‑hydroxy‑2‑propyl)‑1‑oxo‑2‑propyl]‑2‑[2‑(1‑oxo‑2‑propyl)‑1‑ox… (the full systematic name is lengthy; the structure is a 2‑methyl‑3‑hydroxy‑5‑dimethyl‑6‑(3‑hydroxy‑3‑methyl‑butanoyl)‑octa‑hydro‑1‑benzopyran).
The molecule contains a lactone ring, a side‑chain hydroxy‑acid moiety, and a lipophilic aliphatic chain, conferring high membrane permeability.
Monacolin K is a pro‑drug; after oral absorption the lactone opens to the active β‑hydroxy‑acid (the HMG‑CoA reductase inhibitor).

Commercial RYR is produced by inoculating polished rice with Monascus purpureus strains under controlled fermentation (temperature ≈ 30 °C, pH ≈ 5.5).
After fermentation, the rice is dried, milled, and extracted with ethanol or water to obtain a powder or capsule‑grade product.
Quality varies widely.
The presence of monacolin K is verified by HPLC.
Manufacturers must test for citrinin—a nephrotoxic mycotoxin occasionally produced by Monascus under poor conditions.
High‑quality supplements come from certified manufacturers that conduct batch‑specific monacolin K quantification (≥5 mg per dose) and certify low‑citrinin levels (<2 ppb).
Asian countries (China, Korea) are the primary sources.
Stringent GMP practices are essential to ensure safety and potency.