Quality Concerns and What CL Tested for:
Glucosamine and Chondroitin:
Chondroitin is an expensive material, so experts have been concerned about the quality and quantity of the ingredient in supplements. Because chondroitin typically comes from cow cartilage, an additional concern has been whether the products may be contaminated with bovine spongiform encephalitis, the causative agent (a "prion") of Mad Cow Disease. The risk, however, seems to be miniscule for several reasons: First, the chondroitin would have to come from an infected cow, of which none have been reported in the United States. However, imports of chondroitin haven't received the same scrutiny as meat products. Second, the prion is known to exist only in very low levels in cartilage; it's most abundant in nervous and glandular tissues. Third, some manufacturers have stated that the process used to make chondroitin supplements should inactivate the prion — although this hasn't been shown conclusively. Unfortunately, there's no simple way to test for BSE prion contamination in supplements, so products in this review weren't evaluated for contamination.
What CL Found:
Among the products that ConsumerLab.com selected and tested, problems were found only among combination products, four of which were low in chondroitin sulfate — a particularly expensive ingredient. These four products are listed as "Not Approved" in the table below and had the following short-comings:
One product, for human use, claimed to contain 500 mg per serving of "Chondroitin sulfate complex" which ConsumerLab.com's testing showed to contain less than 90 mg of chondroitin sulfate — only 18% of the 500 milligrams. ConsumerLab.com has cautioned consumers in the past to be wary of supplements with ingredients that include words such as "complex," "formula," or "blend" when the weight of each component is not listed. While it may be legal for a manufacturer to use these terms, ConsumerLab.com often finds such information misleading to consumers.
A second product for human use contained less than 85% of its claimed chondroitin sulfate.
Shockingly, no chondroitin sulfate could be detected in two pet supplements despite each displaying a "guaranteed analysis" showing a significant amount of chondroitin sulfate.