ConsumerLab.com purchased and tested more than 50 human and pet osteoarthritis supplements containing  glucosamine, chondroitin, and MSM and found some of the products to be contaminated with lead, missing certain listed ingredients, or have inadequate labeling. 
One-third of people who take multiple dietary supplements take a joint health supplement according to the latest ConsumerLab.com consumer survey. Sales of these supplements exceed $800 million according to 2010 figures from Nutrition Business Journal. Clinical studies suggest that the combination of glucosamine and chondroitin can reduce moderate to severe knee pain due to osteoarthritis. Chondroitin may also significantly decrease pain due to osteoarthritis of the hands. The evidence for MSM in treating osteoarthritis in people remains preliminary.
 
Among the 21 people products selected by ConsumerLab.comwhich contained glucosamine and/or chondroitin, four products* failed to pass ConsumerLab.com’s review. A supplement sold by a national chain was contaminated with 13.2 micrograms of lead per daily serving – exceeding the 0.5 mcg limit set by the State of California (the only state to set a limit), above which a warning label is required. Lead accumulates in the body and, at high levels, can adversely affect the nervous system and increase blood pressure. Children are particularly sensitive to lead and should not be exposed to more than 6 mcg in total per day. Adults can tolerate higher levels of lead, but unnecessary exposure should be avoided. A supplement sold by another national brand was also contaminated with lead, although at a lower level — 1.7 micrograms of lead per daily serving.
 
Three products for people were mislabeled: the most expensive supplement tested (costing over $2 per day) contained only 71.5% of its claimed chondroitin; another product lacked a required shellfish allergen warning (its glucosamine is made from crab shell), and another lacked a warning for people with the genetic disease phenylketonuria, as it contained the artificial sweetener acesulfame K.
 
In a separate review of products formulated for dogs, cats and horses, three of the six products selected by ConsumerLab.com passed quality criteria. One product contained only 4.5% of its chondroitin. Two products for dogs and/or cats contained lead above ConsumerLab.com’s limit (the same used for products for people). Lead was also found in one horse supplement. ConsumerLab.com also looked at pet foods promoted for “mobility” or “healthy joints” but careful review of their labels found they provided relatively little glucosamine and chondroitin.
 
The Product Review of Joint Supplements (for people) is available online and covers the following 43 supplements (including 20 approved in ConsumerLab.com’s Voluntary Certification program and one product similar to another that was approved):

• 21st Century Glucosamine 750 Chondroitin 600 Triple Strength
• BioGenesis Nutraceuticals ArthroGenx
• Cosamin DS
• CVS pharmacy MSM
• Doctor’s BEST Best MSM 1500
• Dr. David Williams Joint Advantage Gold Advanced Relief
• Drinkables Liquid Supplements Liquid Joint Care
• Elations Healthier Joints
• FeelAnew Glucosamine and Chondroitin with Nexrutine
• Finest Natural Glucosamine Chondroitin Double Strength
• GNC Glucosamine 750 Chondroitin 600
• GNC Triflex       
• GNC TriFlex Complete Vitapak Fast Acting
• GNC TriFlex Complete Vitapak MSM
• GNC Triflex Fast-Acting
• Jarrow Formulas Glucosamine + Chondroitin + MSM
• Joint Juice Glucosamine-Chondroitin Blueberry Acai
• KAL Glucosamine Chondroitin MSM
• Maxi-Health Super Glucosamine Complex
• Maximum Strength DONA Crystalline Glucosamine Sulfate
• Nature Made Triple Flex
• Nature’s Bounty Flex-a-min Triple Strength with Joint Flex
• NOW Vegetarian Glucosamine & MSM
• Nutrilite glucosamine-7
• Nutri-Supreme Research Ultra Joint Support with Glucosamine and OptiMSM
• Osteo Bi-Flex Advanced
• Puritan’s Pride Premium Glucosamine HCL
• Schiff Move Free Advanced
• Shaklee Joint Health Complex
• Simply Right Triple Strength Glucosamine and Chondroitin
• Source Naturals Chondroitin Sulfate
• Spring Valley MSM
• Thorne Research Glucosamine and Chondroitin
• Trace Minerals Research ActivJoint Platinum
• Trader Joe’s Glucosamine Chondroitin
• TR CAPS TR Joint Plus Caps 8 Hour Time-Release
• Twinlab Joint Fuel
• USANA Optimizers Procosa
• Vitamin Shoppe Joint Solutions Triple Strength Glucosamine & Chondroitin with MSM
• Vitamin World Triple Strength Glucosamine HCL
• Webber naturals Glucosamine Chondroitin MSM
• Wellesse Joint Movement Glucosamine
• Whole Foods Glucosamine and Chondroitin Complex

The Product Review of Joint Supplements for Dogs, Cats, and Horses is separately available online and covers the following 12 products (including six approved in ConsumerLab.com’s Voluntary Certification program):

• 21st Century Glucosamine and Chondroitin Level 2 Moderate Joint Support
• Cosequin Bonelets Plus
• Cosequin Joint Health Supplement for Cats
• Cosequin Optimized with MSM
• Doc Roy’s Aches Away Soft Chews
• Doctors Foster and Smith Joint Care Level 3
• Grand Meadows SmartPak Grand Complete
• Joint Complete for Dogs and Cats
• Joint Max Regular Strength for Smaller Dogs and Cats
• Liquid Health Naturals K9 Glucosamine Hip & Joint Formula
• Nutri-Vet Hip and Joint Level 2 Moderate Care for Dogs
• Travco Products CuraFlex XS Bonelets

 
*Five products were originally identified as having failed however ConsumerLab.com issued a press release changing the number of products that failed review from five to four. A product containing the artificial sweetener acesulfame K was originally classified as failing to pass the Review for not including a warning for people with phenylketonuria. While such a warning is required for the artificial sweetener aspartame, it is not required for acesulfame K, the artificial sweetener in this particular product.