Red yeast rice naturally contains lovastatin and related statin (or monacolin) compounds which can dramatically lower LDL ("bad") cholesterol. The statins are produced by a special yeast as it digests rice (creating a red color). In fact, it was from yeast cultures that lovastatin (also known as monacolin K) was originally discovered and later marketed as the brand name drug Mevacor. The regulatory problem is that a dietary supplement label cannot indicate that it contains a drug, nor list the amount of that drug. So, while red yeast rice can be legally sold as a supplement, the amount of lovastatin cannot appear on the label — otherwise it could be subject to removal from the market as an unauthorized drug. Technically, it is not even legal for a supplement to contain a drug, so some red yeast rice supplements do not contain lovastatin, despite the fact that it should, naturally, be there.
To help consumers, ConsumerLab.com has been periodically purchasing and testing red yeast rice supplements since 2008 and reporting the amounts of statin compounds they contain. It also reports the amounts of a contaminant, citrinin, which may be toxic to the kidneys. ConsumerLab.com has found an enormous range in the amounts of lovastatin compounds among products. In 2014, for example, it found these amounts to range as little as 0.05 mg to 25.1 mg per daily suggested serving — a 500-fold difference. This means some products are likely to be effective while others are not, and there is no way to tell from the labels alone.
To find out how much lovastatin (and citrinin contaminant) ConsumerLab.com has found in red yeast rice supplements and which ones are, therefore, likely to be effective, see ConsumerLab.com's Red Yeast Rice Supplements Review >>