Glucosamine/Chondroitin Products Not Measuring Up

From the WebMD Archives

April 2, 2000 (San Diego) -- So that glucosamine or chondroitin product doesn't seem to be doing much for the sore joints? There could be a simple reason, according to a study presented at the American Nutraceutical Association's annual conference. Researchers have found some brands contain only miniscule amounts of these supposedly active ingredients.

"What we're trying to do here is raise consciousness about dietary supplements ... and it's not just glucosamine and chondroitin," says Natalie Eddington, PhD, director of the Pharmacokinetics-Biopharmaceutics Lab at the University of Maryland School of Pharmacy in Baltimore. "This is a problem with a number of dietary supplements and herbals on the market, because they're not regulated by a federal agency. So the buyer has to beware."

In all, Eddington studied 14 products containing glucosamine and another 11 containing chondroitin -- both ingredients touted as promoting joint health, usually in patients with osteoarthritis. Among the glucosamine products, one contained only 25% of the active ingredient claimed on the label. Others fell significantly shy of label claims -- though not quite so dramatically -- and a few actually exceeded them.

Results were much worse for chondroitin. Four products contained less than half what the label claimed, and one actually hovered near zero. In addition, Eddington noted a disturbing variability within bottles of two brands, meaning that the content of active ingredient was so wide-ranging that consumers using those particular products can't be sure how much chondroitin they're getting with each dose.

A second analysis -- involving 32 brands -- found even more evidence of a chondroitin-content problem. Eddington found that only five products among this group -- about 16% -- contained what their labels claimed they did, with many of those tested having almost no supplement at all.

"It could be the raw ingredients. [Or, it] could be the manufacturer is not focussed on quality control," Eddington tells WebMD. Whatever the reason, she says any prescription product that fared so poorly in testing "would not be on the market."

What darkens the picture even more for chondroitin users is an analysis Eddington performed on five batches of the raw material used to make the products. Using a well-accepted pharmaceutical technique, she found four of the five exhibited poor "permeability" and thus a low likelihood of absorption in the human body. In other words, even capsules containing the right amount of chondroitin might do the consumer little good if made with those raw materials.

"There are many manufacturers and no manufacturing standards, and that concerns us," says John Klippel, MD, medical director for The Arthritis Foundation. Klippel tells WebMD consumers can follow a couple of guidelines that might steer them toward a fair deal -- but emphasizes that evidence that glucosamine/chondroitin products actually work in the long run for osteoarthritis is still somewhat scant.

"Consider using products that have been subject of scientific research," says Klippel. If possible, identify a product that has been used in a human study. Furthermore, use those from reputable manufacturers. "That is a little complicated because the consumer is not sure what that means," he adds. To the Arthritis Foundation, it means, at the very least, a company they've heard of. But patients should not look for a recommendation from the Foundation -- they're not endorsing any of these products.

Randall Tackett, PhD, professor of pharmacology at the University of Georgia in Athens, says he's not surprised with the study results, and adds that it puts pharmacists in a difficult position when patients ask for recommendations on nutritional products. "We're seeing more pharmacists taking more training in [supplements], but still, there is no [instructor] who is going to say 'this is the best brand.'"

"It can create a very confusing situation," Tackett says. "To consumers, glucosamine is glucosamine. They may go into a pharmacy and see one advertised at two for ten dollars. I'd say err on the side of caution. You've got to wonder how much quality assurance can be put in when the brand is priced way below competing compounds."

But Eddington found 'getting what you pay for' apparently doesn't apply to chondroitin products. While many of the worst performers did cost the least, that wasn't always the case. Two expensive -- four-dollar-a-day -- products tested terribly: Both contained almost no chondroitin.