Do you love curried dishes from India? If so, indulge yourself, because they contain turmeric, a bright yellow-orange spice that can put a zing in your diet and a zip in your step… and your horse's.
Turmeric is a plant in the ginger family whose roots (rhizomes) contain curcumin, which has been observed in humans and other species to be a natural anti-oxidant, anti-inflammatory, and free-radical scavenger.
Ten years ago, researchers began to study its effects in horses. But like the exotic lands where turmeric originates, mystery surrounds how curcumin achieves its effects in horses. Both anecdotal reports and clinical results show that something positive is happening in the horse's body, yet no evidence of curcumin or its metabolites can be found in the horse's blood, a characteristic called bioavailability. Researchers continue to question how curcumin can be active if no proof exists that it enters the circulation.
Dr. Tom Schell has extensively researched curcumin's effects in horses at his Nouvelle Research in Jonesville, NC. Before devoting all his time to research, he operated a successful equine practice, Timbercreek Veterinary Hospital. Schell is board-certified in equine practice, and he is certified in Chinese herbal medicine by the College of Integrative Veterinary Therapy.
Schell explained that drugs and herbs cannot be assessed in the same way when it comes to bioavailability.
“We have research that says people that eat a whole-food based diet, say a cup of spinach every day, are able to reduce cholesterol levels and inflammatory markers. It actually works. It improves health,” he said. “Do we look for blood levels of spinach? No, we don't, because we know it's a food.”
Schell's research into curcumin relied on clinical impact, which combines subjective observation, such as an improvement in lameness score, and quantitative analysis of inflammatory markers in the horse's body.
“Our research paper that we did in 2005, we had curcumin levels measured [for bioavailability] in those horses, and it didn't even register two hours post-ingestion,” he said. “But yet the prostaglandin, the COX levels, and interleukin-1 levels [all measures of inflammation] dropped within those joints, and those horses actually clinically improved. So if we're going to say bioavailability is a problem, then how are we explaining that the patients are actually responding to it?”
Dr. Rebecca Atkinson and her colleagues at Southern Illinois University were familiar with the effects of curcumin in other species, including parasite control in goats. They designed a study to see if curcumin affected parasites, opportunistic bacteria in the gut, and inflammation in horses. In their 12-horse study, half the horses received 15 grams of curcumin per day for 30 days and the other half received a placebo. Atkinson's team saw a change only in inflammation.
“We did not see a decrease in parasites, but we did see a decrease in inflammation after dosing it for 14 days,” Atkinson said. “However, it started to go back up by day 30. … We think if we would have upped the dose a little, we possibly would have seen a difference.”
Dr. Amanda Adams and her team at the University of Kentucky Gluck Equine Research Center studied the anti-inflammatory effects of curcumin and similar polyphenols on the blood of aged horses in the laboratory (in vitro) and on aged horses themselves (in vivo). The researchers chose aged horses because of their propensity for chronic inflammation associated with aging.
The in vitro (laboratory) results on blood showed curcumin was better than other polyphenols, such as resveratrol, in reducing the production of cytokines associated with inflammation. Excited about their results, the team's next step was to assess the anti-inflammatory effects in live senior horses. But the in vivo study showed no changes in inflammation.
“I don't want to say that curcumin was not effective, because we saw it was very effective in vitro,” Adams said. “What we can't answer at this point in time is whether our results were because the dose we used was too low or the fact that maybe the horse is not breaking down curcumin, it's not bioavailable; but I can't see that to be the reason. I think it's a dose problem. … That is what we don't know, and that is what we're working on now moving forward.”
Schell believes the problem can be solved by going back to nature. He said turmeric contains more substances than just curcumin, and it is the synergy provided in the original plant that makes it bioavailable and more effective.
“If you look at turmeric, it has natural volatile oils to it, so it has a fat content,” Schell said. “So the Good Lord took those active ingredients that are fat soluble and mixed it with a fat and put it into a plant. So curcumin has poor bioavailability, but that's because we extracted it from the herb. If we would have left it in its mother form, bioavailability would not be an issue. … The volatile oils not only enhance absorption, but they themselves have extremely strong anti-inflammatory properties.”
Other researchers confirm that curcumin should be combined with some sort of fat to obtain the best results.
While Schell was still in practice, he developed a curcumin supplement, Cur-OST, that contains turmeric and green tea extract. More than 150 horses in his practice were on the supplement. Owners reported their horses seemed to feel better, had a better overall attitude, and their lameness had improved. Yet the bioavailability issue continues to nag at the clinical results.
“When you see the improvement in a horse and then you hear someone say you can't use it because it isn't absorbed, you just have to scratch your head,” Schell said.
Atkinson and Adams plan to pursue their work with curcumin because both believe it has merit for horses, although how it achieves its effects remains elusive.
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