A review of almost 50 glucosamine, chondroitin and MSM supplements shows that some are unlikely to help patients with joint disease as they do not contain sufficient amounts of the declared ingredients.
The products, used widely to help osteoarthritis, generated $790 million in sales in the US last year, noted ConsumerLab.com, author of the review.
While most products contained the claimed ingredients, two combination products contained significantly less of the expected chondroitin. Chondroitin costs about 10 times as much as glucosamine and may help prevent the breakdown of joint cartilage.
"The problem of missing chondroitin is one that we first identified three years ago looking at products for human use," said Dr Tod Cooperman, ConsumerLab.com's president.
The review concerned 49 products, including six for pet treatments. The problems occurred only among combination products, four of which were low in chondroitin sulfate. One claimed to contain 500 mg per serving of 'chondroitin sulfate complex' but ConsumerLab.com tests showed it contained less than 90 mg of chondroitin sulfate - 18 per cent of the 500 milligrams.
This confirms previous advice 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, said ConsumerLab. This information can be misleading to consumers.
A second product for human use contained less than 85 per cent of its claimed chondroitin sulfate. However all of the tablet and caplet products properly disintegrated on testing and all of the MSM products lacked DMSO contamination.
The products that passed the review included brands manufactured by Vitamin World, Nature's Made, Now Foods, Nature's Bounty and Rexall Sundown.
ConsumerLab is currently testing another ingredient used for osteoarthritis as well as depression - SAMe - for a review to be published this month.Glucosamine and chondroitin sulfate supplements are used to slow the progression of osteoarthritis and to reduce the associated pain. Glucosamine is thought to promote the formation and repair of cartilage. Chondroitin is believed to promote water retention and elasticity in cartilage and inhibit enzymes that break down cartilage. The cost of chondroitin has raised concern for the quality and quantity of the ingredient in supplements. MSM is used primarily for treating pain associated with osteoarthritis but has been proposed for treating other conditions including rheumatoid arthritis, inflammation of the bladder wall (interstitial cystitis), snoring, muscle spasm, and cancer. However its efficacy has not been well established.