What is Monacoline K and how does it affect cholesterol levels?

Monacolin K, a substance found in red yeast rice, is gaining popularity as a natural supplement to lower cholesterol.

But what exactly is monacolin K? How does it work? And is it a safe alternative to statins?

This article tells you everything you need to know about the benefits and risks of red yeast rice.

Monacolin K is a naturally occurring substance found in red yeast rice. Monacolin K is chemically identical to lovastatin, a statin used to lower cholesterol.

At least 10 different monacolins may be present in red rice, with monacolin K occurring in the highest concentration.

Red rice yeast is a traditional Chinese medicinal ingredient used as both a flavoring and coloring agent in dishes. It is also called red koji.

It is produced by fermenting rice (Oryza sativa) with the fungus Monascus purpureus , which gives the rice its deep red color.

During this fermentation process, several active substances are formed, including monacolin K.

In Europe, red yeast rice has become popular as a dietary supplement because the monacolin K from red yeast rice works in a similar way to statins.

Statins are medications prescribed to lower cholesterol levels and possibly reduce the risk of cardiovascular disease.

They work by inhibiting an enzyme (HMG-CoA reductase) that plays a key role in the production of cholesterol in the liver.

Although lovastatin is not a registered medicine in the Netherlands, other statins such as atorvastatin, fluvastatin, pravastatin, rosuvastatin and simvastatin are.

Red yeast rice has several health benefits, largely due to monacolin K. These are the benefits of red yeast rice:

• According to scientific research, monacolin K from red yeast rice can contribute to the maintenance of normal cholesterol levels in the blood
• Research shows that red yeast rice is well tolerated . (1)
• In addition, there are indications that it could support heart health , but more research is needed to confirm this effect.

While there is a lot of evidence about most of these health benefits, there are also concerns about the safety of red yeast rice supplements.

There is debate about red yeast rice for 3 different reasons:

Because monacolin K in red yeast rice has the same effect as the medicinal statin lovastatin, there is discussion about whether the supplement should fall under medicines legislation.

In the United States, the FDA has determined that products containing high concentrations of monacolin K are considered drugs, meaning they cannot be sold without approval.

In Europe, supplements up to 3 mg of monacolin K are considered safe. Above that level, these substances are classified as medications.

Red yeast rice, in high doses, can, like statins, have side effects such as muscle pain and possibly kidney and liver problems.

There is also a risk of contamination with citrinin, a toxic mycotoxin produced by certain fungi under unfavorable production conditions and particularly harmful to the kidneys.

European legislation sets a limit of 2 micrograms per kilogram to ensure safety.

Reliable brands perform quality controls and often provide test certificates proving their product is free from harmful substances such as citrinin.

Because of these health risks, regulations have recently been changed to a maximum daily dose of 3 mg in supplements. 

This is controversial, as a significant cholesterol reduction requires a dose of at least 10 mg , according to the European Food Safety Authority .(2)

This dosage is based on the proven effective amounts of medicinal statins, which range from 10 to 80 mg per day.(3)(4)

What does that mean? Is it safe or not to take monacolin K or red yeast rice?

Doses up to 3 mg are safe , above which you may experience side effects.

I mentioned earlier that complaints such as muscle pain and liver problems have been reported.

These are all the side effects of red yeast rice known so far:

• Muscle pain
• Stomach and intestinal complaints
• Mild headache
• Reduced iron levels
• Decreased memory
• Muscle breakdown
• Pancreatitis
• Liver problems(3)(4)(5)

Much research has been done on red yeast rice and the effects of monacolin K.

And although the conclusion of the European legislation is clear about the maximum dosage of red yeast rice, I was curious about what science has been able to establish so far about its effects.

I found these 4 meta-analyses that link the most recent studies:

1. 2014 meta-analysis (13 studies, 804 participants) : showed changes in total cholesterol, LDL and triglycerides, without serious adverse events. (7)
2. 2015 meta-analysis (20 studies) : found a reduction in LDL (1.02 mmol/L), comparable to statins, with a low incidence (0-5%) for kidney/liver. (1)
3. 2019 meta-analysis (53 studies, 8,500 participants) : no increased risk of muscle problems and possibly fewer other side effects. (8)
4. 2022 meta-analysis (15 studies, 1012 participants) : suggests beneficial effects on cholesterol levels; further research is recommended. (9)

Red yeast rice is a commonly used supplement in the Netherlands for lowering total and LDL cholesterol and is a natural alternative to statins for most people. However, people in high-risk groups should exercise caution and discuss its use with their healthcare provider.

Studies show that red yeast rice supplements have similar effects to statins, but are better tolerated.

Legislation limits the daily dose to 3 mg, while the EFSA recommends a dose of 10 mg for significant cholesterol reduction. Therefore, start with a lower dose and carefully monitor its effect on your cholesterol and any side effects.

Before purchasing a monacolin K or red yeast rice supplement, check whether it has been tested for citrinin. A reputable product is citrinin-free and provides clear test results.