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What is red yeast rice?

Despite its name, red yeast rice is not the kind of rice you can serve up with a curry or mix into a risotto. It's made with mould - not yeast - and sold as a supplement in pill or capsule form under the more appealing name of red yeast rice.

Red yeast rice is made by fermenting regular rice with a mould called Monascus purpureus, which gives it its distinctive reddish-purple colour. This mould infuses the rice with chemical substances called monacolins. One substance in particular - monacolin K - is almost identical in structural makeup to the cholesterol lowering medicine, lovastatin¹.

The prescription drug lovastatin is a statin that lowers the body's cholesterol production to stop it from building up inside your arteries. Blocked arteries are bad for your health and can prevent your blood from reaching the heart, brain and other important organs. This can increase your chances of having a heart attack or stroke.

Lovastatin belongs to a group of medicines that work similarly to lower your cholesterol levels. The most commonly prescribed statins in the UK are:

• Atorvastatin.

• Pravastatin.

• Rosuvastatin.

• Simvastatin.

Research into the effects of red yeast rice on other conditions including heart health are inconclusive but are ongoing.

Metabolic Syndrome

Metabolic syndrome refers to a group of conditions that contribute to heart disease, stroke and type 2 diabetes. These include:

• High levels of bad cholesterol.

• Increased blood pressure.

• High blood sugar.

• Abdominal obesity - extra fat in your tummy area.

Because red yeast rice could help lower cholesterol, studies are exploring its potential to help moderate metabolic syndrome-related conditions such as high cholesterol, blood pressure and blood sugar² - again, more research is needed to understand the effects.

Mohr explains that the dosage of red yeast rice can vary depending on the specific product and the concentration of active compounds it has.

"Dosages used in studies have ranged from 600 to 1,200 milligrams taken twice a day," he says. "It’s important to talk to a healthcare provider before starting this or any new supplement because if the active ingredient - monacolin K - is too high, it's too similar to those in prescription statin medications."

There is no recommended dosage of red yeast rice supplements as the amount of monacolin K can vary in each product. This can vary widely between brands.

Many red yeast rice dietary supplements bought in health food stores or online shops have either little to no monacolin K - or contain it in high amounts. This means that - due to lack of regulation - there's no way for you to know how much monacolin K you're getting from these supplements - which could potentially be dangerous, especially if you are on other medication.

Though red yeast rice may be natural, research shows its side effects may be similar to statins.

Commonly reported side effects of red yeast rice supplements include:

• Digestive issues such as tummy pain, heartburn, gas and bloating³.

• Muscle pain and weakness, and in rare cases rhabdomyolysis. This is a condition where skeletal muscle tissue disintegrates and leaks into your bloodstream⁴.

• Increased chances of liver damage at high doses or long-term use.

Red yeast rice is not recommended for people with kidney or liver disease as it may worsen their condition.

Does red yeast rice interfere with medicines?

"Red yeast rice may interact with certain medicines - especially other cholesterol-lowering drugs like statins, since it can have a similar active ingredient," Mohr warns. "It's important to talk with a doctor before starting red yeast rice to avoid potential negative interactions - particularly concerning liver health or medications affecting liver enzymes."

Overall, studies show the effectiveness of red yeast rice products present a complex mix of benefits and side effects. It's not currently considered a safe alternative to cholesterol-lowering prescription medicines though.

Given the lack of regulation for red yeast rice, talk to your doctor to see whether it's really suitable for you. Prescription medications - with established research and safety regulations - may be more reliable.

1. Klimek et al: Safety and Efficacy of Red Yeast Rice (Monascus purpureus) as an Alternative Therapy for Hyperlipidemia

2. Patel: Functional food red yeast rice (RYR) for metabolic syndrome amelioration: a review on pros and cons

3. NIH: Red Yeast Rice: What You Need To Know