Study finds ‘marked variability’ in red yeast rice supplements

By Nathan Gray

- Last updated on GMT

Related tags Red yeast rice Statin

Commercially available formulations of red yeast rice are extremely variable in the concentration of active ingredients they contain, according to a report published in the Archives of Internal Medicine.

The new study reports that levels of monacolins in red yeast rice – a supplement marketed as a way to improve cholesterol levels – vary massively between different over-the-counter brands, with one in three products also containing a potentially toxic compound.

“We found striking variability in monacolin content in 12 proprietary red yeast rice products and the presence of citrinin in one-third of the formulations tested,”​ said the researchers, led by Dr. Ram Gordon at the University of Pennsylvania.

“Our results highlight an important issue with red yeast rice and many other alternative medicines: the lack of standardization of active constituents,”​ they warned.


Chinese red yeast rice – also known as Hong Qu – is a medicinal agent and food colorant made by culturing the yeast, Monascus purpureus​, on rice.

When performed under sterile and controlled conditions this produces a group of compounds called monacolins that inhibit HMGCoA, a rate limiting reductase enzyme important in cholesterol synthesis.

Although statins and other proven lipid-lowering therapies are widely available, the authors note that many people seek alternative therapies such as red yeast rice in an attempt to ‘naturally’ lower their cholesterol levels.

Red yeast rice contains 14 active compounds, called monacolins that inhibit hepatic cholesterol synthesis. Previous research suggests that specific formulations of red yeast rice reduce low-density lipoprotein (LDL) cholesterol significantly compared with placebo.

However, the authors said that in order to avoid being considered an unapproved drug by the FDA, manufacturers do not standardize or disclose the levels of monacolin K (also known as lovastatin) or other monacolins in their products.

They added that, consequently, there may be considerable variation in the composition of monacolins in red yeast rice products from different manufacturers and discrepancies between label information and actual content.

“Nevertheless, red yeast rice remains widely available to the public as an over-the-counter dietary supplement,”​ noted Dr. Gordon and colleagues.

The new study evaluated monacolin levels in twelve commercially available red yeast rice formulations, and also tested for citrinin, a toxin from fungus that is potentially harmful to the kidneys.

Marked variability

Dr. Gordon and colleagues reported “marked variability”​ in the 12 red yeast rice products tested between August 2006 and June 2008.

Levels of total monacolins were seen to range from 0.31 milligrams per capsule to 11.15 milligrams per capsule.

The researchers found monacolin K lovastatin ranged from 0.10 milligrams to 10.09 milligrams per capsule, and monacolin KA was found to range between 0.00 and 2.30 mg per capsule.

The researchers also discovered that one in three products had elevated levels of potentially toxic citrinin​.

Variable quality

The researchers claimed that “limited governmental oversight and variable quality control by manufacturers”​ means that the monacolin content of different red yeast rice products may differ dramatically from bottle to bottle.

However they added that the levels of monacolins and citrinin for the products tested in their research “should be considered specific to the batches we tested”​.

“It is possible that current good manufacturing practices specific for dietary supplements… may have reduced the chance of batch-to-batch variability. However, this regulation would not be expected to reduce brand-to-brand variability,”​ commented the authors.

“Although red yeast rice may have potential as an alternative lipid lowering agent, our findings suggest the need for improved standardization of red yeast rice products and product labelling,”​ stated the researchers.

“Until this occurs, physicians should be cautious in recommending red yeast rice to their patients for the treatment of hyperlipidemia and primary and secondary prevention of cardiovascular disease,”​ they added.

Source: Archives of Internal Medicine
Volume 170, Issue 19, Pages 1722-1727, doi: 10.1001/archinternmed.2010.382
“Marked Variability of Monacolin Levels in Commercial Red Yeast Rice Products: Buyer Beware​!”
Authors: R.Y. Gordon, T. Cooperman, W. Obermeyer, D.J. Becker

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