Oral Joint Supplements
- Jun 1, 2007
In steps the joint supplement industry.
Over the past several years, the equine nutraceutical market (which includes joint supplements) has exploded in popularity. Horse owners have shelled out millions of dollars on supplements, based on product claims that have little to no scientific backing. For the most part, these supplements go unregulated by the Food and Drug Administration (FDA) Center for Veterinary Medicine because they are low on the agency's priority list. For now, the FDA mainly ensures that these supplements don't claim to treat or cure a medical condition, which would classify them as a drug.
Minimal enforcement in an explosive industry is something that worries leading joint researchers such as Wayne McIlwraith, BVSc, PhD, FRCVS, DSc, DrMedVet (hc), Dipl. ACVS, Barbara Cox Anthony Chair and Director of Orthopaedic Research at Colorado State University.
While some ingredients have been shown to help cartilage at risk, there is an important question that must be answered: Does the supplement you buy contain the ingredients stated on the label in the amounts advertised, and are the ingredients in a form the horse's body can put to use in the joint? The supplement industry has devised a "self-policing" group (discussed below) that will help you make your choices.
But first, let's look at what a supplement is, and what it isn't.
Drugs vs. Nutraceuticals
"Intraarticular-, intravenous-, and intramuscular-administered joint medications are considered to be drugs and are subject to FDA approval," says Florien Jenner, DrMedVet, BVSc, Dipl. ACVS, a lecturer in the School of Veterinary Medicine at University College Dublin in Ireland. "All of these drugs have been tested by independent research and have been shown to be effective. Oral joint supplements (also known as nutraceuticals), however, are not considered to be drugs and are not regulated (for safety or quality) by the FDA."
The term nutraceutical is not recognized by the FDA. It was born from the words "nutrient" and "pharmaceutical."
Policing the nutraceutical market is not a primary goal of the FDA, which contributes to the problem--production of poor-quality products, such as a joint supplement that has low levels of glucosamine compared to what is stated on the label. We aren't picking on glucosamine products, but there is scientific evidence to back up this example.
One University of Guelph study evaluated glucosamine concentration levels in oral equine joint supplements and compared the levels researchers found to what was stated on the labels. Nine of the 23 supplements tested did not contain the amount of glucosamine stated on the labels. What's more, several of the labels called for doses containing less than the recommended 10 grams (the industry standard) of glucosamine per day--something that concerns Scott Weese, DVM, DVSc, Dipl. ACVIM, a researcher in the Department of Clinical Studies at Guelph's Ontario Veterinary College.
"You wonder if it (the supplement with low doses of glucosamine) will actually benefit the horse," Weese says. "The standard recommendation of 10 grams is still somewhat of a guess, but it is a reasonable recommendation, and some products had levels that were very low and nowhere near that."
In another study, researchers at the University of Maryland tested 27 glucosamine or chondroitin sulfate products in one study; a number of them didn't contain the amounts that were listed on the labels. In addition, the amounts even varied from container to container.
With new supplements continuously hitting the market, Weese offers some "red flags" for consumers to be wary of:
- Products that are poorly labeled and have misspellings in their literature and on their product labels;
- Products with no guaranteed analysis of their content; or
- Those with unreasonable label claims.
Smoke and Mirrors
McIlwraith says false or vague product claims are another problem horse owners face. "We (veterinarians) have problems with product claims (such as) 'Goes to work immediately to give your horse maximum joint mobility and flexibility,' " he explains. "I know that's never been demonstrated scientifically, at least not in published medical journals. 'Superior, one-of-a-kind, therapeutic nutraceutical, 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."
Jenner says, "Because these products are not regulated by the FDA, the amount of active ingredient claimed on the label is not necessarily what is contained in the bottle, and great variation can also exist in the purity and the absorbability (ability of the product to be absorbed in its active form after being given orally) of the product. Only a few nutraceuticals have been tested scientifically, which makes it difficult for veterinarians to make recommendations for all but a few oral supplements."
There is one sheriff in this Wild West-like industry--the National Animal Supplement Council (NASC). The group was created by manufacturers in the industry as an effort to self-police product quality. Before a company is allowed to display the NASC seal on a product, it must:
- Have a quality manual in place that provides written standard operating procedures for production process control that ensure the amount of the ingredient on the label matches what's in the product;
- Have an adverse event reporting/complaint system in place to continually monitor and evaluate products;
- Follow proper label guidelines for all products; and
- Include specific warnings and cautionary statements recommended by the FDA's Center for Veterinary Medicine and the NASC Scientific Advisory Committee.
Identifying Quality Products
The gold standard is "they have to have in vivo (tested in the live horse) evidence," McIlwraith says. "In in vitro (outside the horse) trials, the glucosamine doesn't go through the gut." This means the bioavailability of the product can be uncertain.
"There are two in vivo trials that have looked at glucosamine in the horse," McIlwraith says. "One study induced synovitis (inflammation of the synovial membrane) in clinically normal horses and showed that there was no effect." Another study revealed that in 25 cases improvement was shown, but no control horses were available to compare with the study horses.
McIlwraith says there have been several efficacy studies on glucosamine in humans. However, these studies should not be used as a basis for horses because the equine intestinal tract is very different.
So the real question is: Should you use oral joint supplement products to help treat or prevent arthritis in your horse? Unfortunately, there's no clear answer.
"While test tube research does occasionally show some anti-inflammatory and even cartilage protective effects, those effects have yet to be demonstrated in the live horse," says David Ramey, DVM, a private practitioner at a performance horse practice in Calabasas, Calif. "There's no question that the supplements don't seem to be able to hurt your horse (your pocketbook is another matter). There's also no question that many people (including veterinarians) recommend them. But there's also no evidence to date that they are consistently effective in relieving inflammation or promoting cartilage maintenance in horses or in any other species. However, oral joint supplements are almost certain not to work in horses with advanced osteoarthritis, since these horses may not have much cartilage left to restore."
There is currently very little information to assist horse owners or veterinarians in deciding when and how to use oral joint supplements. Low bioavailability of oral glucosamine chondroitin sulfate, poor product quality, label-prescribed doses that are below veterinarian-recommended levels, and a lack of scientific evidence supporting efficacy of popular oral joint supplements are major concerns. If you and your veterinarian decide to use a joint supplement in your horse, look for the NASC seal that proves good manufacturing practices.
About the Author
Chad Mendell is the former Managing Editor for TheHorse.com .
POLL: University Equine Hospitals