Red yeast rice refers to a traditional Chinese medicinal product. Proponents suggest that it may reduce blood cholesterol and other fats in the blood. However, the composition of the product can vary, and it may contain harmful ingredients that can result in adverse effects.

Red yeast rice is a staple food additive popular in East Asian countries that is gaining popularity as a supplement in the West.

People produce the product through a fermentation process involving cooked rice kernels with a Monascaceae mold, typically Monascus purpureus, which turns the rice reddish-purple due to its pigmentation capability. The term purpureus is Latin for dark red.

In addition to turning the rice red, the fermentation process with this yeast produces substances known as monacolins. Notably, monacolin K is chemically identical to an active ingredient in some statins, which can reduce the liver’s production of cholesterol.

However, the composition of red yeast rice varies depending on the yeast strains and culture conditions. Not only may some products contain very little or no monacolin K, but they can also contain harmful contaminants, such as citrinin, which may damage the kidneys.

In this article, we will discuss red yeast rice, including its potential benefits and possible risks.

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Red yeast rice is a culinary and medicinal product in some Asian countries. It is a staple ingredient in traditional Chinese medicine and proponents suggest that it contains many biological properties, including improving blood circulation.

In the West, some manufacturers may market it as a product for high cholesterol. This is because red yeast rice can contain monacolin K, which is identical to the active ingredient in some statins.

This chemical may work through a similar mechanism by inhibiting an enzyme essential for the creation of cholesterol in the liver. However, the quantity of these substances can vary, and consumers may have no way of knowing how much is present in the product.

Some people may refer to red yeast rice as a functional food or a nutraceutical due to its properties. However, unlike statins and all prescription medications, red yeast rice does not undergo regulation.

As such, the U.S. Food and Drug Administration (FDA) deems some red yeast rice products as drugs without approval and notes manufacturers cannot legally sell products with trace amounts of monacolin K as dietary substances.

The potential hypolipidemic substance present in red yeast rice is monacolin K, which belongs to a group of chemicals known as monacolins. Japanese professor Akira Endo first isolated this compound from the fermentation process of Monascus yeast in 1979, which then led to the development of the statin called lovastatin.

Red yeast rice has gained attention as a natural supplement to help lower cholesterol. High cholesterol, particularly low-density lipoprotein (LDL) cholesterol, is a potential risk factor for heart disease.

To lower cholesterol, a doctor can prescribe statins, but some people may not want to take medications and instead want to use natural alternatives such as red yeast rice.

According to a 2019 review, consuming monacolin K in red yeast rice on a daily basis can reduce LDL cholesterol plasma levels by 15–25% within 6–8 weeks. Additionally, red yeast rice may lower markers for inflammation and total cholesterol.

The review suggests that consuming 3–10 milligrams (mg) of monacolin K daily may have low associated risks. Additionally, it indicates that red yeast rice is a safe and effective way to manage mild to moderate hypercholesterolemia in people with no additional cardiovascular risk factors.

A 2016 review highlights other possible benefits, which may include it:

  • controlling high blood pressure
  • being anti-inflammatory
  • being hypoglycemic (lowering blood sugar)
  • having anti-cancer properties
  • being osteogenic (aiding bone formation)

However, the European Food and Safety Authority (EFSA) notes that individuals should be cautious about using red yeast rice due to the wide variability of active ingredients in available formulations and possible harmful effects on health.

Conversely to the above review, the EFSA says intake levels as low as 3 mg daily can result in adverse events.

While anecdotal reports indicate that red yeast rice is a safe and effective way to reduce cholesterol with fewer side effects, clinical evidence suggests otherwise.

A 2020 Dutch study came to the conclusion that people should consider red yeast rice a significant safety concern. It highlighted that exposure to monacolin K could lead to serious adverse effects.

A 2019 mini-review notes there is no support to suggest that red yeast rice can naturally lower or maintain cholesterol levels without comparable side effects to statins.

As such, it suggests that red yeast rice products should come with appropriate warnings and highlight the varying monacolin K content and the scarcity of long-term safety data for these products.

A 2020 study emphasizes the variability in the strength of red yeast rice supplements available in the United States. Analyzing brands of red yeast rice for the presence of monacolin K, the study found that some products contained none, whereas, in others, the quantity ranged more than 60-fold from 0.09–5.48 mg per 1200 mg serving.

Using recommendations for daily serving sizes, this could range more than 120-fold from 0.09–10.94 mg.

The FDA warns against using red yeast rice products, stating that people may risk severe muscle problems leading to kidney impairment. Furthermore, monacolin K present in red yeast rice may interact with medications, including:

  • the antidepressant nefazodone
  • some antibiotics
  • drugs that people use to treat fungal and HIV infections
  • other cholesterol-lowering medications

Additionally, the National Center for Complementary and Integrative Health warns that red yeast rice products may contain citrinin, a toxin that can lead to kidney failure. It adds that people who are pregnant, breastfeeding, or taking statins should avoid red yeast rice.

People who wish to try red yeast rice should consult their doctor first, especially if they currently take medications.

Red yeast rice is available in many formulations, such as an extract, capsule, or tablet. People can follow the instructions on the packaging as a guideline for dosage.

Some sources suggest that people can take 200–1000 mg two or three times daily. However, it is more important for people to be conscious of the monacolin K content.

As the monacolin K content can vary significantly, many consumers may be unaware of how much is present in red yeast rice products.

Furthermore, some sources suggest that manufacturers do not admit the monacolin K content on their packaging for fear of prompting regulatory action from the FDA.

Red yeast rice is a popular food additive in East Asian countries. People can produce red yeast rice by fermenting rice with Monascus yeast, which turns the rice red and produces compounds that may have some health benefits.

This process can produce monacolin K, which is similar to the active compound in lovastatin, a medication to treat high cholesterol levels. However, because red yeast rice products do not undergo regulation, the amount of this compound can vary, and it may also contain other substances harmful to health.

As such, it is advisable for a person to discuss red yeast rice with a healthcare professional before taking it.