The findings were confirmed in a second independent laboratory. The supplements tested included those for people as well as for veterinary use. Tests focused on joint health supplements containing glucosamine, chondroitin and/or MSM (methylsulfonylmethane).
Osteoarthritis affects an estimated 21 million adults in the U.S., making it the most common type of arthritis. Supplements made with glucosamine and/or chondroitin may reduce symptoms by helping to maintain and repair cartilage. These products have become top selling supplements, accounting for $831 million in U.S. sales in 2007, according to Nutrition Business Journal (NBJ). These ingredients, as well as MSM are also commonly used to treat osteoarthritis (also known as degenerative joint disease) in dogs, cats and horses.These products are part of an expanding U.S. pet supplement market estimated at $923 million in 2007 by NBJ.
Among 21 supplements tested for people, four were found to be contaminated with lead—likely to have originated from glucosamine in the supplements, which is made from shrimp or crab shells. Two of these supplements also lacked chondroitin, a particularly expensive ingredient derived from animal cartilage. One of these contained only 5.6% of its chondroitin while the other had no detectable amount. One of the lead contaminated supplements also failed to break apart properly in disintegration testing. Mislabeling of sodium content was the reason for a fifth supplement to fail the review of the supplements for people.
ConsumerLab.com found problems with four of the six animal supplements tested. One supplement sold in capsules contained only 17% of the claimed chondroitin—similar to ConsumerLab.com’s findings for the same product in 2007, at which time the distributor stated that it was voluntarily recalling the product.
A chicken treat provided only 6% of the claimed glucosamine and only 16% of the claimed chondroitin. Each treat provided only about 1 mg of each of these two ingredients—insignificant amounts compared to several hundred milligrams in most other products. Two different liquid supplements provided only 5.4% and 16% of the labeled amount of chondroitin, respectively.
“To cut costs, some manufacturers may withhold chondroitin, which is expensive, or buy poor quality material 'certified' with a non-specific test for chondroitin,” said Dr. William Obermeyer, ConsumerLab.com's vice president for research and a former chemist in the U.S. FDA's Center for Food Safety and Applied Nutrition. “It is similar to how dog foods were contaminated with melamine, which looks like protein in non-specific tests.”
ConsumerLab.com analyzed products with a highly specific test for chondroitin based on high performance liquid chromatography (HPLC).
The results were published today in two separate reports—one on joint health supplements for people and another on joint health supplements for dogs, cats and horses.