Oral Joint Supplements: Do They Work?

In 2005, nutraceutical sales reached more than $1 billion for companion animals. That number is expected to double in the next three years. To veterinarians, this is a disturbing trend for an industry that, for the most part, is unregulated by the FDA and has little scientific basis.

Wayne McIlwraith, BVSc, PhD, FRCVS, DSc, DrMedVet (hc), Dipl. ACVS, Barbara Cox Anthony Chair and Director of Orthopedic Research at Colorado State University (CSU), expressed his concerns about the limited information on oral joint supplements, particularly chondroitin sulfate and glucosamine, at the 2006 AAEP Convention. He said it is unclear how and when to use supplements because many have low bioavailability, poor quality, low recommended doses, and a lack of scientific evidence supporting their effectiveness. He presented this material on the behalf of Stacey Oke, DVM, MSc, and Scott Weese, DVM, DVSc, Dipl. ACVIM, who could not attend the meeting.

Treatment Goals

When faced with joint problems, veterinarians' treatment goals include controlling clinical signs, minimizing pain, and improving joint mobility. McIlwraith said he would add "prevention of advanced degradation of the articular cartilage" to those goals.

"It's certainly a major quest of our Orthopaedic Research Center at CSU that we try to find disease modifying instead of symptom modifying drugs," McIlwraith said.

He spoke briefly about some of the adverse effects associated with non-steroidal anti-inflammatory drugs, as well as some corticosteroids.

"Methlyprednisolone acetate (which is a corticosteroid) causes degradative changes in the cartilage--other corticosteriods do not," he said.

"This industry is proceeding along somewhat independent of veterinarians," he continued. "That's one of the frustrations that we have. We get left out of the loop, at least at this stage, on diagnosis and recommendations for best therapies."

Scientist should concentrate on this industry to regulate inaccuracies and false claims. In 2005, nutraceutical pet sales exceeded $1 billion and that number is expected to grow 15-25% per year at least until 2009. At this rate of growth, McIlwraith said industry sales will be around $2 billion by 2009. His concern lies in the fact that "what we've showed scientifically has nothing to do with it so far. Most of the growth is based on advertising."

What Are Nutraceuticals?

"The term 'nutraceuticals' is not recognized by the FDA in veterinary medicine. It was born from the words nutrition and pharmaceuticals," Mclllwraith said. "A nutraceutical is any substance that is a food or part of a food and provides medical or health benefits including the prevention and treatment of disease.

"The term covers a wide range of products, and it's hardly specific," he said. "The FDA Center of Veterinary Medicine considers all veterinary nutraceuticals products as unapproved drugs, as most of these products claim to treat or cure disease."

He noted that policing the nutraceuticals market is a low priority for the FDA. These lax regulations contribute to the production of poor quality products, such as a product with low levels of glucosamine compared to what the label states. One study showed that only two out of 14 (14%) products contained the amount of ingredients stated on the label.

"Another problem with quality is the recommendation of subtherapeutic doses," he explained. "The current recommended dosage is 20 mg/kg. A lot of products and dosage recommendations don't meet that requirement.

"A third problem with quality is that some products can be contaminated with harmful materials such as lead, pesticides, and DMSO (dimethyl sulfoxide, an anti- inflammatory)," noted McIlwraith. "Another issue is products with confusing or incorrect label claims as the amount of ingredient per scoop weight. The amount of active ingredients could not possibly fit into the serving size."

False or vague product claims are another problem horse owners must face. McIlwraith said, "We have problems with product claims: 'Goes to work immediately to give your horse maximum joint mobility and flexibility.' I know that's never been demonstrated scientifically, at least not in published medical journals. 'Superior, one-of-a-kind, therapeutic, nutraceuticals, that provides extra-strength, full-spectrum support for your horse'. Now, I've been working in joint disease for a long time, and I don't know what 'full-spectrum joint support' is."

Some Facts

Glucosamine is a building block for articular cartilage, and it is a source of keratin sulfate and chondroitin sulfate. There are three forms of glucosamine (sulfate, hydrochloride, or N-acetylglucosamine), which are widely regard as safe.

Identifying quality products The gold standard is "they have to have in vivo evidence," McIlwraith said. "In in vitro studies, the glucosamine doesn't go through the gut." This means the bioavailability of the product can be uncertain because researchers haven't demonstrated its ability to travel from the digestive tract to the joint.

Bioavailability "There are two in vivo trials that have looked at glucosamine in the horse," McIlwraith said. "One study induced synovitis (inflammation of the synovial membrane) in clinically normal horses and showed that there was no effect." Another study showed that in 25 cases improvement was shown, but no control horses were available to compare the study horses to.

McIlwraith said that there have been several joint supplement efficacy studies in humans. However, these studies are hardly useful for horses because the equine's intestinal tract is very different.

Take-Home Message

While glucosamine supplementation is very common, there is currently little information to assist veterinarians in deciding when and how to use these products. Low bioavailability of oral glucosamine, poor product quality, low recommended doses, and a lack of scientific evidence showing efficacy of popular oral joint supplements are major concerns.



Get research and health news from the American Association of Equine Practitioners 2006 Convention in The Horse's AAEP 2006 Wrap-Up sponsored by OCD Equine. Files are available as free PDF downloads.

About the Author

Chad Mendell

Chad Mendell is the former Managing Editor for TheHorse.com .

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