Red yeast rice extract (RYRE) is a traditional Chinese medicine that has been purported to lower cholesterol. Several types of the extract are sold as supplements.

Red yeast rice may be appealing because it's "natural," but you need to be careful. Experts have not studied it extensively. The ideal dosing and its long-term safety are unclear. It could be dangerous for some people. And because the ingredients of different brands of red yeast rice extract might vary so much, it's hard to make firm statements about its effectiveness or safety.

Despite the FDA's attempts, many people in the U.S. still manage to get similar red yeast rice extracts from other countries or on the Internet.

How Well Does Red Yeast Rice Lower Cholesterol?

Studies have shown that certain red yeast rice products that contain statin can significantly lower levels of total cholesterol and specifically LDL, or "bad" cholesterol. One showed that taking 2.4 grams per day reduced LDL levels by 22% and total cholesterol by 16% in 12 weeks. Another study showed that taking 1.2 grams per day lowered LDL levels by 26% in just eight weeks.

However, the results of these studies depend on the amount of statin that is in the extract, and it can vary widely. The FDA considers extracts that contain statins to be illegal in the U.S., but many are still available.

What Is the Correct Dosage of Red Yeast Rice Extract?

Keep in mind that the amount of monacolin -- perhaps the most important ingredient -- in a organic red yeast rice extract can vary a lot. There are many different strains of the yeast. Different types of fermentation are used. One study of different brands of red yeast rice supplements showed that the amount of monacolin ranged from 0% to 0.58%.

So even though studies have shown that RYRE can lower cholesterol, you can't really know if the supplement brand you're using will have that effect.

What Are the Risks of Red Yeast Rice?

Studies have shown that side effects are mild, like headaches, heartburn, and upset stomach. Side effects from prescription lovastatin include elevation of liver enzymes and muscle enzymes, muscle problems, and liver problems.

But more research needs to be done before we can know about the long-term safety of red yeast rice extract. We do know that some types may be more dangerous than others because of high levels of other substances such as citrinic acid.

RYRE also shares some of the same risks as statins, the class of drugs containing lovastatin. Experts say that the risks of lovastatin would logically apply to RYRE -- elevation of liver and muscle enzymes, muscle problems, and liver problems.

The extract may not be safe for everyone. You should not take it if you:

Have kidney disease

Have liver disease

Are pregnant

Are breastfeeding

In addition, anyone taking one of the following medicines should not use red yeast rice:

Statins to control cholesterol such as lovastatin (Mevacor), rosuvastatin (Crestor), fluvastatin (Lescol), atorvastatin (Lipitor), pravastatin (Pravachol), and simvastatin (Zocor)

Other cholesterol drugs such as gemfibrozil (Lopid) and fenofibrate (TriCor)

Drugs to suppress the immune system, like cyclosporine

Antifungal drugs such as fluconazole (Diflucan), ketoconazole (Nizoral), and itraconazole (Sporanox)