Red Yeast Rice (Red Koji)

BACKGROUND

Red yeast rice is rice that is fermented with the red fungus, Monascus purpureus. It has been used in China since around 800 AD for the production of alcoholic beverages, as a preservative, as a dye, and for medicinal benefits, particularly for circulatory and digestive problems.

Fungi were responsible for the first cholesterol-lowering statins ever discovered: Lovastatin (in the 1980s). It became the first commercially produced statin under the brand name Mevacor. Lovastatin is still in use today.

The fungus used to ferment red yeast rice is closely related to the same species that produced these original statin compounds. Red yeast rice naturally contains monacolin K, a molecule chemically identical to lovastatin.

What Does Red Yeast Rice Do for the Body?

The active ingredient of red yeast rice is monacolin K, which blocks an enzyme used by the liver for cholesterol production. It also contains phytosterols, which help control the absorption of cholesterol from the gut.

Considered Properties

Respiratory: N/A

Ears/Eyes/Nose/Throat: N/A

Cardiovascular: Reduces the risk of heart attack and stroke by lowering LDL, total cholesterol, and non-HDL cholesterol; reduces vascular inflammation

Gastrointestinal: N/A

Genitourinary: N/A

Musculoskeletal: N/A

Neurologic: N/A

Skin: N/A

Mental Health: N/A

Glucose: N/A

Cholesterol: Lowers LDL, total, and non-HDL cholesterol. May be a mild reduction in triglycerides and a very slight increase in HDL

Immunity: N/A

Cancer: N/A

Other: N/A

Side Effects: The potential side effects from red yeast rice are very much like those of statins.

More common but generally carry a lower risk than statin medications. More common side effects include muscle pain (myalgia), muscle stiffness, exercise intolerance or weakness, headache, nausea, indigestion, mild diarrhea or loose stools, and abdominal discomfort or cramping.

As with statin medications, mild myalgias may be relieved by CoQ10.

Some less common side effects include: Allergy symptoms (rash, itching, hives, flushing), constipation, bloating or gas, dizziness, sleep disturbances/vivid dreams, fatigue, and loss of appetite. Sometimes people experience headaches, dizziness, rare cognitive complaints (forgetfulness, slowed thinking — reversible), and, rarely, peripheral neuropathy. 

More severe: Liver‑Related: Elevated liver enzymes (ALT/AST), Rare hepatotoxicity, Upper‑right abdominal pain. Also rare rhabdomyolysis, including dark urine (can indicate liver or muscle injury),  profound weakness, elevated CK, and severe muscle pain. 

Most, if not all, monacolin K side effects stop when the red yeast rice is discontinued.

Kidney‑Related (Citrinin Contamination Risk): Kidney irritation, flank pain, changes in urination,

nausea or vomiting (This risk is specific to red yeast rice and not seen with prescription statins.)

CAUTION/CONTRANDICATIONS: Drug‑Interaction Effects: Increased side effects when combined with CYP3A4‑interacting drugs, increased potency and side effects with grapefruit, Higher risk of muscle or liver issues with certain antibiotics, antifungals, antiviral medications

FORMS: Capsules, tablets, powders (fermented rice powder), liquid extract/tincture, foods – the problem with taking this powder as an addition is that it delivers unpredictable quantities of lovastatin (it is, by the way, described as “earthy”, mildly sweet, and slightly bitter).

DOSAGE:

1,200 – 2,00 mg daily in standardized doses

RECOMMENDED BRANDS

Reputable brands of red yeast rice are hard to find. The FDA does not allow supplements to list lovastatin or monacolin K on their labels because this is a prescribed drug (Mevacor). Instead, they are allowed to list monacolin. Unfortunately, many (even good brands) have suboptimal levels of lovastatin contained in their product; they are not allowed to list it as an ingredient at all, so it's hard to know which supplement will be effective. You also want to watch for a potentially toxic substance - a toxic byproduct of the fungi/mold itself, depending on the strain and environmental conditions.

It is best to check third-party testers if you decide to take this.

When I checked this out on the third-party testing site, ConsumerLab, two out of seven reputable supplements passed the test for adequate amounts of Monacolin K (aka lovastatin) and the presence and amount of the toxin citrinin.

One I found on one of my partner/affiliate sites includes the following (see information about my affiliate sites below):

Thorne Choleast-900 – Order through Fullscript 

Dietary Sources

**Affiliate brands: There are other brands of red yeast rice; however, I partner with reputable, high-quality affiliate brands to bring you products that meet standards for safety, effectiveness, and transparency. When you click a link and make a purchase, I may earn a small commission at no extra cost to you — a simple way to support this free website and its mission. I do the research so you can shop with confidence.

*Disclaimer: The material above is for informational purposes only. This information is not intended to diagnose, treat, or cure a condition. The uses listed above are tentative; some have been or are undergoing research trials, but many are not FDA-approved. You must investigate these supplements further before deciding to use them. Check interactions and contraindications on sites like Drugs.com or WebMD. Do not attempt to treat a serious condition like liver or kidney problems, high blood pressure, heart conditions, cancer, diabetes, or thyroid issues without discussing it with a healthcare provider first. If you are pregnant, do not use supplements without discussing it with your healthcare provider.