Researchers at the University of Alberta recently concluded a study aimed at determining the quality of over- the-counter GLS products available in Canadian health food stores. They obtained samples of 15 products from different manufacturers and analyzed their content of GLS and the free base glucosamine, which is believed to be the active ingredient. They observed one immediate problem with the labeling. Many GLS products did not state whether the 500 mg they contained was 500 mg of GLS or 500 mg of glucosamine, the active component. This is important, as 500 mg of GLS would contain, at most, 394 mg of glucosamine. The researchers found that the amount of glucosamine present in the samples varied widely from the amount stated on the label. Some brands claiming a content of 500 mg of GLS per capsule actually contained as little as 295 mg and only 2 out of 15 actually contained 500 mg or more of GLS. One brand had a labeled content of 1500 mg of GLS, but in actual fact contained only 800 mg. Generally, the products contained only around 50-60% of the stated amount of GLS. The researchers recommend that the exact amount of free glucosamine present in the tablets or capsules be stated on the label.
Russell, Anthony S., et al. Active ingredient consistency of commercially available glucosamine sulfate products. Journal of Rheumatology, Vol. 29, November 2002, pp. 2407-09
Editor's comment: I personally find it very disturbing and sad that 13 out of 15 of what I have, until now, considered reputable Canadian supplement manufacturers have been found to shortchange their customers by as much as 50% when it comes to the labeling and sale of GLS.