Turmeric has been used historically in Indian and Chinese medicine as an anti-inflammatory agent. The key ingredient of turmeric is curcumin. It is offered to horses for many reasons, but most commonly appears to be for the management of pain and arthritis and the treatment of sarcoids.
Dr. David Marlin, a renowned equine physiologist and owner of Science Supplements, has done extensive research into the use of turmeric. In human research, there are ample studies investigating the effectiveness of curcumin, particularly for diseases and conditions such as cancer, diabetes, arthritis and Alzheimer’s, with many promising results. There are two articles that have investigated turmeric and/or curcumin in in vitro studies (studies done on cells or tissues, not on a live animal) in horses, looking at anti-inflammatory effects. One study (Franck et al., Physiological Research 2008) reported curcuminoids had an inhibitory effect on oxidative activity of neutrophils (white blood cells); that is, they had antioxidative and anti-inflammatory effects. Another in vitro study investigated the protective effects of curcumin on an arthritis model (Clutterbuck et al, Ann NY Acad Sci, 2009). These authors found a 20-27 per cent decrease in glycosaminoglycan (GAG) release from the cartilage when joint cells were exposed to 100μmol/L, suggesting less cartilage breakdown had occurred, while no effect was seen at a 10μmol/L dose. For a 500kg horse, with about 38L of blood, and assuming the synovial fluid around the joint would reach the same concentration of curcumin that would be in the blood, 60 per cent absorption of curcumin and two per cent curcumin in turmeric, it would take feeding the horse 113g of turmeric to reach similar concentrations. Considering most supplements containing turmeric are only providing 5g (or less) of turmeric, the concentrations in any joint fluids will not reach the level obtained in the study. Also, as identified in the paper, there have not been safety studies conducted, nor has true efficacy been proven in a horse.
Dr. Marlin has also pointed out that despite the widespread popularity of using turmeric as a treatment for equine sarcoids, there is not a single research article investigating this in any species.
Despite a lack of evidence of its efficacy, turmeric is a popular supplement, which can be found at most health food stores, and there are several equine products that contain turmeric. Human users are encouraged to consume it with crushed black pepper and/or oil to enhance absorption. However, Dr. Marlin has reported that work in animals suggests they may be more efficient at absorbing curcumin than humans, and that pepper and oil may not be needed.
While the above suggests that horses would need a lot (113g) to be effective, there hasn’t been any safety studies conducted in horses. Safety studies in humans haven’t seen side effects at 2.5g per day (for a 60kg person, which would equate to 20.8g for a 500kg horse). Therefore, it would appear that turmeric is relatively safe in small quantities.