Yonkers, N.Y.—Seven of the 16 glucosamine/chondroitin supplements tested by Consumer Reports did not contain their claimed level of chondroitin, and two of those did not a pass dissolution test, according to an article in the publication's October 2013 issue. Testing methods may be to blame for the discrepancy, according to industry experts.
Consumer Reports tested products that contained a combination of glucosamine salt (either hydrochloride or sulfate) and chondroitin sulfate bought online or from stores in the New York area from August to October 2012. The publication said it had outside labs test samples of the products to see if they contained at least 90 percent of labeled amount of glucosamine and chondroitin.
Consumer Reports tested for dissolution based on criteria used by the U.S. Pharmacopeia (USP); at least 75 percent of the labeled amounts must dissolve in water within one hour. Consumer Reports also tested for the heavy metals arsenic, cadmium, lead and mercury, using criteria set by EPA, USP and California's Proposition 65.
The tests found all of the products contained their labeled amount of glucosamine, and none failed the heavy metal tests. However, six products had only 79 to 87 percent of their claimed chondroitin, and a seventh product only had 65 percent.
CVS/Pharmacy's Triple Strength chondroitin was one of the supplements that did not live up to label claims. "We are reviewing Consumer Reports’ study of joint care supplements, as well as their methodology," the company said it a statement, adding it has commissioned an independent, third-party lab to review the results and perform an independent test. "CVS/pharmacy’s rigorous testing program for our store brands is designed to maximize quality and assure the products we offer are safe, work as intended, comply with regulations and satisfy customers."
Two of the supplements—one tablet and one caplet—also did not pass the dissolution test, leading Consumer Reports to note the ingredients might not be fully available for absorption.
Cara Welch, Ph.D., senior vice president of scientific and regulatory affairs at the Natural Products Association (NPA), said the test results were unfortunate, but not surprising. "Chondroitin sulfate is well know to be vulnerable to adulteration in general, but it's often economically motivated," she said.
Consumer Reports didn't publish what methods they used to test the supplements, and it did not respond to INSIDER's inquiries on the subject. Welch said many reasons could cause these products to be below their label claims for chondroitin, but it's most likely due to testing methods.
The easiest, fastest and cheapest method to test chondroitin sulfate is called cetyl pyridinium chloride (CPC) titration, which was commonly used for a number of years, but Welch explained newer tests have shown it is not specific enough. "You can add other things in there that fool the test into thinking there is more chondroitin sulfate," she said.
In this test, CPC reacts with specific ions such as sulfate and others; this method is not specific to chondroitin sulfate. Other saccharides can also react in the same way that chondroitin sulfate does.
To get specific testing on chondroitin sulfate, Welch recommended using an enzymatic HPLC (high-performance liquid chromatography) assay, which is an official AOAC method. This method is based on the specific enzymatic activity of chondroitin sulfate, leaving less chance of interference from other materials.
"Responsible industry needs to step up and take the matters into their own hands," Welch said, offering this advice: "Find a better testing method a and use that better method. It is important to find suppliers that you trust, and to qualify those suppliers. You need to set specifications for ingredients and verify ingredients meet those specifications."
Also, Welch added companies shouldn't purchase by cost alone. "It leaves you even more vulnerable to purchasing adulterated products."
Consumer Reports has a history of testing dietary supplements, as well as disparaging the industry. Last summer, the publication issued an article titled, "Vitamins & Supplements: 10 Dangers that May Surprise You." Industry responded by saying many of the "dangers" were exaggerated or unfounded. In 2010, they released an article on " 12 Dangerous Supplements to Avoid;" industry pointed out some of the supplements were not dangerous or were not readily available on the market.