IngredientsRed yeast rice (RYR) is rice that has been fermented with the mold Monascus purpureus. Several species other than that isolated in 1895 and named Monascus purpureus in recognition of its purple color have also been widely used in making red wine and red-colored foods. These Monascus fermentation products are called Red Yeast Rice (RYR) in Western countries, although the designation "yeast" is incorrect, as Monascus is a filamentous fungus and not a yeast. Red yeast rice is also known as red fermented rice, red kojic rice, or red koji rice from its Japanese name, and anka or angkak from Southern Min pronunciations of its Chinese name.
It is treated as a food in China, a functional supplement in Japan, a regulated medicine in Australia, an unapproved drug in the United States, and an up-until-recently permitted supplement in Europe. In China it is widely available as the proprietary preparation Xuezhikang (血脂康).
Red yeast rice is produced by cultivating the mold species Monascus purpureus on rice for 3–6 days at room temperature. The rice grains turn bright red at the core and reddish purple on the outside. The fully cultured rice is then either sold as the dried grain, or cooked and pasteurized to be sold as a wet paste, or dried and pulverized to be sold as a fine powder.
Different strains of Monascus fungus will produce different amounts of monacolins. The 'Went' strain of Monascus purpureus, when properly fermented and processed, will yield a dried red yeast rice powder that is approximately 0.4% monacolins, of which roughly half will be monacolin K (chemically identical to lovastatin).
Red yeast rice is sold in jars at Asian markets as a pasteurized wet aggregate, whole dried grains, or as a ground powder. In Western markets it is primarily formulated as standardized capsules or tablets containing RYR extract. Thirteen of thirty-one RYR dietary supplements analyzed in one study (42%) did not provide label information on the concentration of monacolins, and only nine of the eighteen formulations with an indication (50%) actually contained the declared amount of monacolins. Amounts of monacolin K in dietary supplements labeled as containing 600 mg of RYR varied more than 40-fold, from 0.03 mg to 2.18 mg. Monacolin K content of dietary supplements labeled as containing 1200 mg RYR varied more than 20-fold, from 0.22 mg to 5.23 mg.
The use of red yeast rice in China dates back over two millennia. It was first recorded in the gazetteer Local Chronicles of Gutian, written during the Tang dynasty (618–907 AD), and since then was documented in many classical medical texts such as Qing Yi Lu (c. 907–1127), Materia Medica in Daily (c. 1271–1368), and Compendium of Materia Medica (1578). Other historical records from the Tang dynasty describe its medicinal applications, particularly for promoting blood circulation and improving digestion.
Red yeast rice is recorded in Bencao Gangmu (Compendium of Materia Medica), a representative book on Chinese medicine written in 1596 that has been highly valued since ancient times in China. Red yeast rice is documented as Chinese herbal cuisine that improves blood circulation in Nichiyo-Honzo, a Chinese herbology book written by Duan Wu in 1329. Red yeast rice was also called tan-giku, and its production method is described in Tiangong Kaiwu, a compendium on industry, agriculture, and artisanry written by Song Ying in the 17th century in China.
RYR has been used as an herbal supplement and in the cuisine of East Asian countries including China, Japan, and Korea. It has been used for flavoring, coloring, and preservation of food and in traditional Chinese medicine for many years. Red yeast rice is used to color a wide variety of food products, including fermented tofu, red rice vinegar, char siu, Peking duck, and Chinese pastries that require red food coloring. 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. Red yeast rice has been used to produce alcoholic beverages and various fermented foods in China and Korea since ancient times; it has also been used to produce tofuyo (Okinawan-style fermented tofu) in Japan since the 18th century.
Red yeast rice (RYR), a Chinese traditional folk medicine produced by the fermentation of cooked rice kernels with a Monascaceae mold, Monascus purpureus, has long been used to treat blood circulation stasis, indigestion, diarrhea, and limb weakness in East Asian countries. In traditional Chinese medicine (TCM), red yeast rice is considered mild in nature, slightly sweet, and non-toxic. It is believed to act on the liver, spleen, and large intestine meridians. Red yeast rice was commonly used to treat conditions such as indigestion, diarrhea, fatigue, and limb weakness, and was sometimes recommended as part of the diet for individuals with heart-related ailments.
It has been used for more than a thousand years in East Asian countries for producing rice wine, for flavoring, coloring, and preservation of foods as well as a folk medicine for improving food digestion and blood circulation. A medicinal remedy and health food since ancient times, it has been used in at least 24 TCM prescriptions for treating various chronic diseases.
After soaking in water for 7 days, polished rice is steamed, and the lees of Shaoxing wine are added as seed fungi and cultured in a tile room for about 1 week. This method is very similar to that used in the production of yellow koji in Japan. Monascus fungi have low proliferative ability, and about 1 week is required for the production of red yeast rice, though only 2 days are required for yellow koji.
More than 101 chemical constituents have been isolated from RYR, mainly consisting of monacolins, pigments, organic acids, sterols, decalin derivatives, flavonoids, polysaccharides, and other compounds. Red yeast rice contains 25% to 73% sugars (starch in particular), 14% to 31% proteins, 2% to 7% water, 1% to 5% fatty acids, sterols, isoflavones, pigments such as rubropunctamine and monascorubramine, and polyketides.
Monacolins inhibit HMG CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase, the rate-limiting step in cholesterol synthesis. At least 13 monacolins have been isolated from RYR, of which monacolin K is chemically similar to lovastatin, a cholesterol-lowering drug. A total of 14 monacolin compounds have been identified, such as monacolin K (mevinolin), J, L, M, X, and their hydroxy acid forms, as well as dehydromonacolin K, dihydromonacolin L, compactin, and 3alpha-hydroxy-3,5-dihydromonacolin L.
Monacolin K from red yeast rice is chemically identical to the statin drug lovastatin, creating a global regulatory conflict over whether a naturally fermented food-derived compound should be classified as a food, supplement, or prescription medicine. The controversy stems from the paradox that monacolin K, produced naturally through the fermentation of traditional red yeast rice, is chemically identical to the cholesterol-lowering drug lovastatin.
Red yeast rice also contains monacolin KA, the hydroxy acid (activated) form of lovastatin, which is the form that is active after lovastatin passes through the liver. Together, monacolin K and monacolin KA (collectively referred to as "total lovastatin") are typically the predominant monacolins in red yeast rice.
In recent years, large-scale commercial production of red yeast rice using traditional solid-state fermentation has become possible, and various useful materials, including a variety of Monascus pigments (polyketides) that spread as natural pigments, in addition to statins, are produced in the fermentation process. These pigments — including rubropunctamine and monascorubramine — contribute to the characteristic red color and have attracted independent pharmacological investigation. Beyond monacolins, red yeast rice contains other secondary metabolites including Monascus pigments (natural red-orange colorants), gamma-aminobutyric acid (GABA), and dimerumic acid.
Red yeast rice also contains fiber, sterols, isoflavones, isoflavone glycosides, and monounsaturated fatty acids, all of which may also contribute to its lipid-lowering effects.
The fermentation process for making red yeast rice can also introduce a poisonous byproduct called citrinin. Citrinin is a mycotoxin — a toxic substance that can develop while fermenting rice in Monascus. Citrinin is described as nephrotoxic and teratogenic and resulted in the development of renal tumors in rats.
In the 1970s, Japanese microbiologist Akira Endo identified cholesterol-lowering compounds produced by fungi, including monacolin K–related substances. His research established that these compounds inhibit the enzyme HMG-CoA reductase, a key regulatory step in cholesterol biosynthesis. The prodrug lovastatin, after gastrointestinal absorption and hydrolysis into the active hydroxy acid form, is metabolized mainly in the liver by CYP-3A4.
Participants in RYR studies took the equivalent of only 5 mg/d to 6 mg/d of lovastatin, with resultant LDL-C reductions of 25 to 40 percent, equivalent to reductions seen with 20 mg/d to 40 mg/d of lovastatin in other trials. Red yeast rice's potency is likely explained by the presence of monacolins other than monacolin K that may act synergistically to inhibit HMG-CoA reductase. One of the most common synergistic mechanisms differentiating the use of a botanical from a pure compound involves the modulation of bioaccessibility induced by co-occurring substances, that may hamper or facilitate the process.
The most extensively studied application of RYR is its lipid-lowering effect. The body of evidence includes multiple randomized controlled trials (RCTs) and several published meta-analyses.
Meta-analytic evidence: A total of 13 randomized, placebo-controlled trials containing 804 participants were analyzed in one pooled analysis. Red yeast rice exhibited significant lowering effects on serum total cholesterol (TC) [WMD = −0.97 (95% CI: −1.13, −0.80) mmol/L, P<0.001], triglycerides (TG) [WMD = −0.23 (95% CI: −0.31, −0.14) mmol/L, P<0.001], and LDL-C [WMD = −0.87 (95% CI: −1.03, −0.71) mmol/L, P<0.001], but no significant increasing effect on HDL-C compared with placebo. No serious side effects were reported in all trials.
The lipid-lowering efficacy of RYR has been confirmed by some meta-analyses of randomized clinical trials (RCTs), the most recent one including 20 trials and 6,663 subjects, and showing that, after 2 to 24 months of treatment, RYR reduced LDL-C on average of 1.02 mmol/L (95% confidence interval: −1.20 to −0.83) (39.4 mg/dL) compared with placebo, which was comparable to the reduction achieved with low-intensity/low-dosed statins (pravastatin 40 mg, simvastatin 10 mg, lovastatin 20 mg).
Fourteen double-blinded clinical trials identified in a 2024 systematic review and meta-analysis, with interventions lasting 4–24 weeks, found that RYR extract consumption statistically significantly reduced total cholesterol (mean absolute reduction: 37.43 mg/dL; 95% CI: −47.08, −27.79) and LDL-C (mean absolute reduction: 35.82 mg/dL; 95% CI: −43.36, −28.29), but not HDL-C, triglycerides, or apolipoproteins A-I and B.
Comparison to statins: In comparison to statins, RYR was more effective in lowering TG (MD, −19.90; 95% CI, −32.22 to −7.58; p = 0.002), comparable in lowering LDL-C and elevating HDL-C, and less effective in lowering TC (MD, 12.24; 95% CI, 2.19 to 22.29; p = 0.02).
Statin-intolerant populations: A randomized, controlled trial set in a community-based cardiology practice evaluated the effectiveness and tolerability of red yeast rice and therapeutic lifestyle change in patients who cannot tolerate statin therapy. The study enrolled 62 patients with dyslipidemia and a history of discontinuation of statin therapy due to myalgias. Patients received red yeast rice 1,800 mg (31 patients) or placebo (31 patients) twice daily for 24 weeks. All patients were concomitantly enrolled in a 12-week therapeutic lifestyle change program.
Carotid atherosclerosis: Twenty RCTs with 2,217 patients were included in a meta-analysis assessing RYR's effects on carotid atherosclerosis. Compared to the control group, carotid plaque area, intima-media thickness, and plaque score were all significantly reduced, alongside significant improvements in LDL-C, triglycerides, and total cholesterol, and an increase in HDL-C following RYR therapy.
The China Coronary Secondary Prevention Study (CCSPS): The landmark cardiovascular outcomes trial for RYR is the CCSPS, which tested the proprietary preparation Xuezhikang. Results of well-controlled prospective clinical trials had shown the efficacy of lipid-lowering therapies in western populations, but had not been reported with a Chinese population. This multicenter study was conducted to determine the effects of Xuezhikang (XZK), a partially purified extract of red yeast rice, on lipoprotein and cardiovascular endpoints in Chinese patients who experienced a previous myocardial infarction. Nearly 5,000 of these patients with average low-density lipoprotein cholesterol levels at baseline were randomly assigned either to placebo or to XZK daily for an average of 4.5 years. The CCSPS (4,870 patients, follow-up 4 years) produced a 46% reduction in nonfatal myocardial infarction and coronary death.
In a sub-analysis, 1,530 elderly hypertensive patients (≥65 years old) with previous MI were assigned either to placebo (n = 758) or to Xuezhikang (n = 772) daily for an average of 4.5 years.
Myocardial infarction patients with borderline hypercholesterolemia: A separate meta-analysis assessed the efficacy of RYR extract in MI patients with borderline hypercholesterolemia. Seven studies with 10,699 MI patients were included. Follow-up periods ranged from 4 weeks to 4.5 years, and the studies were overall of high quality with low risk of bias. RYR extract at 1,200 mg/day reduced nonfatal MI (RR = 0.42, 95% CI 0.34 to 0.52), revascularization (RR = 0.58, 95% CI 0.48 to 0.71), and sudden death (RR = 0.71, 95% CI 0.53 to 0.94).
Limitation note: The CCSPS and related Chinese trials have been conducted almost exclusively in Chinese populations using the specific Xuezhikang formulation; the degree to which these results generalize to other RYR preparations and non-Chinese populations is uncertain. Funding from commercial sponsors in some studies has also been noted as a limitation.
The RYR-berberine association has also been tested in association with ezetimibe in statin-intolerant patients, reaching LDL-C reduction of approximately 35% and TG reduction of approximately 25% compared with baseline, which is similar to what has been reported for moderate-intensity statins.
In a double-blind, placebo-controlled RCT evaluating the effect of phytosterols 800 mg and RYR (monacolin K 5 mg) and their association in 90 hypercholesterolemic subjects, the group treated with the nutraceutical association experienced an LDL-C reduction by 27% and apoB decrease by 19% (both p < 0.001).
Data from a meta-analysis of 14 RCTs involving 3,159 subjects indicated that the RYR-policosanol-berberine association can improve LDL-C by 23.6 mg/dL, HDL-C by 2.71 mg/dL, TG by 14.2 mg/dL, and glucose by 2.52 mg/dL.
Pharmacological studies have revealed that RYR possesses many biological properties with hypolipidemic, anti-atherosclerotic, anti-cancer, neurocytoprotective, hepatoprotective, anti-osteoporotic, anti-fatigue, anti-diabetic, anti-obesity, immunomodulatory, anti-inflammatory, anti-hypertensive, and anti-microbial activities. However, it is essential to note that the evidence for most of these activities is at the preclinical stage (cell culture or animal model) and does not yet constitute established clinical evidence in humans.
Doses used in clinical research have varied considerably depending on the preparation, formulation, and indication. The following dosages are as reported in identified sources:
The wide variation in dosages across trials reflects the fundamental product standardization problem in this field: total RYR mass is a poor proxy for active monacolin content. Supplement labels in the US typically list only the amount of red yeast rice per serving — not the amount of monacolins — making it very difficult for consumers to compare products.
Red yeast rice products that contain significant amounts of monacolin K can have the same potential side effects as statin drugs, including muscle, kidney, and liver damage. They may also cause digestive problems such as diarrhea, nausea, and stomach pain.
Taking red yeast rice products actually has similar effects to taking lovastatin, even though the potency is significantly lower, and the potential for side effects and interactions similar to those of statin drugs is to be assumed. Strong CYP-3A4 inhibitors, in particular, can increase the risk of myopathy by increasing drug plasma concentration and consequently the inhibition of HMG-CoA reductase during lovastatin or red yeast rice therapy. These inhibitors include, for example, cyclosporin, itraconazole, clarithromycin, verapamil, aprepitant, amiodarone, as well as HIV protease inhibitors such as ritonavir and other cholesterol-lowering agents such as fibrates.
There are reports in the literature of muscle myopathy and liver damage resulting from red yeast rice usage. From a review: "The potential safety signals of myopathies and liver injury raise the hypothesis that the safety profile of RYR is similar to that of statins." Large doses of monacolin K also increase the risk of rhabdomyolysis — a condition where muscles break down.
Adverse effects associated with red yeast rice that are repeatedly reported include symptomatic myopathy, gastrointestinal symptoms, and elevated levels of hepatic enzymes indicative of liver stress. In one case, doctors admitted an otherwise healthy, active 64-year-old woman to the hospital after she took a 1.2-gram red yeast supplement for 6 weeks. The supplement led to liver poisoning. The woman recovered following steroid treatment, but this is not the only recorded hospital admission linking red yeast rice supplements and liver poisoning.
Some red yeast rice products contain a contaminant called citrinin, which is toxic and can damage the kidneys. In a 2021 analysis of 37 red yeast rice products, only one had citrinin levels below the maximum level currently set by the European Union. Also, four products that were contaminated with citrinin were labeled as "citrinin-free."
Taking red yeast rice products and statins at the same time can easily lead to overdosing and side effects. Red yeast rice products can have the same types of drug interactions as statin drugs and therefore may interfere with certain medicines or increase the chance for side effects.
According to EU Regulation (EU) 2022/860, food supplements containing monacolins from RYR should hold a labelling requirement stating: "Should not be consumed by pregnant or lactating women, children below 18 years old and adults above 70 years old." The risk of myopathy/rhabdomyolysis is increased by concomitant use of lovastatin with certain other medicinal products, and the use of lovastatin by pregnant and lactating women is discouraged.
Sudan red G can be found as an adulterant in RYR. One published analysis reported several commercial products as being almost entirely monacolin K — which would occur if the drug lovastatin was illegally added — rather than the expected composition of many monacolin compounds.
The US Food and Drug Administration (FDA) position is that red yeast rice products that contain monacolin K are identical to a prescription drug and, thus, subject to regulation as a drug.
In the European Union, the regulatory trajectory has moved toward progressively tighter restrictions. On June 21, 2022, a new EU regulation came into effect limiting the monacolin K content per recommended daily serving to less than 3 mg. The maximum level of citrinin (100 μg/kg) in food supplements based on rice fermented with the red yeast Monascus purpureus is regulated by Regulation (EU) 2023/915. In January 2025, the European Food Safety Authority (EFSA) released its final scientific opinion concluding there is no safe intake level for monacolins from red yeast rice in food supplements. In July 2024, the European Commission revoked the health claim for monacolin K at 10 mg/day. In February 2025, EFSA concluded monacolins pose significant risks at any dose, potentially leading to prohibition by mid-2026.
A 2019 systematic review of clinical trials suggested that red yeast rice products with varying levels of monacolin K were safe. But this went against the opinion of the European Food Safety Authority (EFSA), published in 2018, which concluded that exposure to monacolin K from red yeast rice products could lead to severe side effects.
The compound is treated as a food in China, a functional supplement in Japan, a regulated medicine in Australia, an unapproved drug in the United States, and an up-until-recently permitted supplement in Europe.
Health conditions that Red yeast rice may help support.
RYR contains multiple antioxidant-active compounds—including Monascus pigments (rubropunctatin, monascorubrin), sterols, and isoflavones—that demonstrably reduce markers of oxidative stress in both animal models and human trials. Clinical data show reductions in oxidized LDL (oxLDL) and Lp-PLA2 in metabolic syndrome patients. Mechanistic studies confirm RYR elevates antioxidant enzymes (SOD, CAT, GSH) and reduces lipid peroxidation marker MDA.
Red yeast rice contains monacolin K (identical to lovastatin) and naturally occurring monacolins that inhibit HMG-CoA reductase, reducing LDL cholesterol—a major driver of arterial plaque formation. Multiple RCTs confirm LDL reduction of 15–25%, reducing atherosclerosis progression. A 2009 RCT combining berberine, red yeast rice, and policosanol improved endothelial function and lipid levels.
Evidence for RYR's effect on blood pressure is mixed but leans toward modest systolic benefit, particularly when combined with conventional antihypertensive therapy or olive extract. A meta-analysis of 21 RCTs (4,558 patients) found that RYR plus conventional therapy significantly lowered systolic blood pressure versus placebo plus conventional therapy. However, RYR as monotherapy shows inconsistent effects on diastolic pressure, and several individual RCTs show no significant BP change. The NIH NCCIH lists blood pressure reduction among potential effects of high-monacolin-K products.
Multiple RCTs and meta-analyses report that RYR preparations reduce fasting plasma glucose, HbA1c, and insulin resistance (HOMA-IR) in subjects with metabolic syndrome. Effects are modest and typically observed alongside lipid-lowering. Mechanistic data suggest monacolin K's HMG-CoA reductase inhibition and antioxidant activity may partially protect pancreatic islets. Evidence is strongest for populations with concurrent dyslipidemia and metabolic syndrome.
Red yeast rice contains monacolin K, structurally identical to lovastatin, which inhibits HMG-CoA reductase and lowers LDL-C by 15–25% within 6–8 weeks. A 5,000-patient Chinese RCT over 4.5 years showed a 17.6% LDL reduction and 30% reduction in cardiovascular mortality. It is considered the most effective cholesterol-lowering nutraceutical.
Clinical trials and meta-analyses report that RYR reduces high-sensitivity CRP (hs-CRP), a key systemic inflammatory biomarker, in dyslipidemic and metabolic syndrome populations. The anti-inflammatory effect appears to be partly indirect, mediated through lipid lowering and endothelial protection, rather than direct cytokine blockade. A 2022 triple-blind RCT (n=92) and several other trials have measured and confirmed hs-CRP reductions with RYR supplementation.
RYR has documented effects on vascular function including improvements in endothelial function, reduction of carotid intima-media thickness (IMT), and anti-atherosclerotic actions in clinical populations. Traditional Chinese medicine documented its use specifically for 'promoting blood circulation and releasing stasis' since at least the Ming Dynasty. Clinical meta-analyses confirm anti-atherosclerotic benefit, and human trials show improved endothelial markers.
Preclinical studies demonstrate that RYR exerts anti-aging effects by reducing oxidative stress damage, modulating NF-κB-driven inflammation, slowing apoptosis, and favorably reshaping the gut microbiome in D-galactose-induced aging models. Epidemiological and clinical data also link long-term RYR use to reduced cardiovascular mortality and liver cirrhosis risk, which are key aging-related outcomes. The traditional use of RYR as a body-rejuvenating agent provides additional historical context.
Red yeast rice (RYR) contains monacolin K, a compound chemically identical to the prescription statin lovastatin, which inhibits HMG-CoA reductase — the rate-limiting enzyme in hepatic cholesterol synthesis. Multiple randomized controlled trials and meta-analyses demonstrate that standardized RYR preparations reduce LDL-C by 15–25% within 6–8 weeks. A large landmark Chinese RCT (Xuezhikang, ~5,000 post-MI patients) found a 45% reduction in recurrent heart attack risk and roughly one-third reduction in cardiovascular mortality over five years.
Red Yeast Rice (RYR) has direct clinical evidence supporting its use across multiple components of Metabolic Syndrome (MetS). Its active constituent, monacolin K — chemically identical to the statin lovastatin — inhibits HMG-CoA reductase, lowering LDL cholesterol, triglycerides, and total cholesterol. A 2022 systematic review and meta-analysis of 30 RCTs (n=5,440) published in Frontiers in Pharmacology found RYR preparations significantly reduced mortality, major cardiovascular events, fasting glucose, HbA1c, insulin resistance, and blood pressure in MetS patients. Evidence is strongest for dyslipidemia management; effects on abdominal obesity remain less studied.
Red yeast rice (Monascus purpureus fermented rice) contains monacolins including monacolin K (a natural statin), which lower LDL cholesterol and triglycerides. A meta-analysis of 13 RCTs found significant TG reductions (WMD = −0.23 mmol/L, p<0.001). A second meta-analysis of 15 high-quality RCTs showed red yeast rice was more effective than statins for TG lowering.
Body systems that Red yeast rice may help support.
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