Researchers from the University of Maryland’s Department of Pharmaceutical Sciences, School of Pharmacy, recently published a report that showed some over-the-counter human products claiming to contain glucosamine and chondroitin did not have the amounts claimed on the label. In fact, deviation from label claims ranged from 0% to more than 115%.

The objective of the re- search, published in the Journal of the American Nutraceutical Association, was “to evaluate the results of analysis of actual contents of several products in the marketplace containing glucosamine and/or chondroitin sulfate and to determine if they significantly deviate from label claim.” The researchers took 14 products containing glucosa-mine hydrochloride or glucosamine sulfate and 11 products containing chondroitin sulfate to evaluate using one method (UV-HPLC). They also took 32 products containing only chondroitin sulfate to test with another method (titration). This analysis was “an attempt to evaluate whether different suppliers of glucosamine or chondroitin sulfate use different grades of material.”

What the researchers found was that some products didn’t contain any of the labeled materials, and some contained more than was labeled. “Our results suggest that there is a significant deviation between the content of the active ingredients (glucosamine or chondroitin sulfate) and what is stated by the manufacturers on the label.” They also discovered that products with a retail price “of less than or equal to one dollar per 1,200 mg of chondroitin sulfate were found to be seriously deficient in meeting label claim (less than 10% of label claim).”

The study also examined the intestinal transport (an indirect method to evaluate intestinal absorption) of several marketed sources of chondroitin sulfate to determine if these products could be absorbed in the GI tract. The researchers assessed permeability of various marketed sources of raw materials of chondroitin sulfate across Caco-2 cell monolayers