I Want My XZK!

Recently I have been developing written handouts for my patients regarding cardiovascular disease (CVD) prevention.  As I was researching over-the-counter (OTC) supplements for heart health, and assessing the scientific validity behind them, I came across a stunning study from China which indicates that Xuezhikang (XZK), a preparation of a common dietary supplement, red yeast rice (RYR) may be more effective at preventing CVD than any of the prescription drugs marketed by Big Pharma.

Extracts of RYR have been used as a food flavoring and for therapy of circulatory disorders in China for centuries.  These extracts can lower cholesterol primarily because of the presence of substances known as monacolins.  One of these, monacolin K, is identical to lovastatin, which was originally isolated from a mold.  Lovastatin was subsequently found to lower cholesterol by interfering with an enzyme critical for its production, and was marketed as Mevacor, after approval by the FDA.

Mevacor was the first of a class of drugs known as "statins" which are the most common drugs used to treat high cholesterol in this country.  Marketed under brand names such as Zocor, Lipitor and Crestor, these drugs became a multi-billion dollar industry in the 1990's and 2000's.  Lipitor alone was responsible for $12.4 billion in sales in 2008.  In the mean time, dozens of clinical studies were performed to show the benefits of statins in reducing CVD risk in a broader range of patients, including those with normal or modestly elevated cholesterol levels who were not considered candidates for statin therapy just a few years previously.  Researchers, pharmaceutical companies and the FDA were all acting to ensure that more and more people would be candidates for their "wonder drugs".

In 1998, the FDA ruled that since monacolin K is identical to lovastatin, that RYR products containing it were subject to regulation as drugs, and banned them.  In 2003 RYR products began to trickle back into the market.  If they made no claims about cholesterol and did not contain monacolin K, then RYR products were not subject to FDA regulation.  In 2007 the FDA issued a statement warning that consumers should "…not buy or eat red yeast rice products…may contain an unauthorized drug that could be harmful to health".  From the FDA's perspective, consumers might not realize that they were exposing themselves to the potential side effects of lovastatin, including liver damage, muscle aches, and kidney failure.

XZK (Xuezhikang) is a partially purified RYR with multiple components.  Each 300 mg. capsule contains about 3 mg. of lovastatin, so the recommended dose of 4 capsules daily means a 10-15 mg. dose of lovastatin daily.  The usual recommended daily dose of Mevacor is 40-80 mg. 

Between 1996 and 2003, nearly 5,000 Chinese patients with a documented history of a heart attack were entered into a study to determine whether XZK could prevent subsequent heart attack, need for angioplasty and bypass surgery, and the risk of death from all causes, as well as from heart disease specifically.  The average level of LDL-Cholesterol (LDL-C, "bad cholesterol") in the study group was 129.  U.S. guidelines recommend an LDL-C level of under 100 in patients like these, under 70 if they are diabetic.  Each patient was followed for an average of 4.5 years.

The results were astonishing.  Fatal and non-fatal heart attacks were reduced by 33% and 62% respectively.  Total cardiovascular deaths were reduced by 30%, and all-cause deaths were reduced by 33%.  Although not a primary or secondary endpoint of the study, cancer deaths in the XZK group were reduced 56%.  These impressive results were obtained despite the treatment group experiencing a relatively modest 18% drop in LDL-C.  Statins at typically used doses lower LDL-C from 35-50%.   No serious side effects were reported in those taking XZK, and the number of patients in the two groups who experienced any side effects or discontinued treatment was the same.

How impressive are these results?  The CARE (Cholesterol And Recurrent Events) trial, which utilized pravastatin in a very similar patient population, demonstrated only a 24% reduction in fatal and non-fatal heart attack, and no significant reduction in all causes of death.

There are a few caveats here, most obviously, the question of whether the results of a study done on a (presumably) Chinese-only population are applicable to a US population consisting of many ethnic groups, and whether other formulations of RYR are as effective as XZK in reducing CVD risk.  There is speculation that XZK's non-monacolin  components, such as isoflavones (antioxidant compounds found mostly in legumes, which are thought to reduce the incidence of some cancers) may have contributed to the results.

So where can you get this amazing, natural supplement that may significantly reduce the risk of dying of a heart attack or cancer?  The short answer is, you can't.  XZK's lovastatin content prevents it from being sold in the United States, and other forms of RYR don't have the weight of a large clinical trial behind them.  Intrepid online shoppers, however, may be able to find a source.