In the first peer-reviewed, published study to evaluate the effects of the nutritional supplement methylsulfonylmethane (MSM) in horses, Spanish researchers found that MSM exerted a protective effect against the detrimental physiologic changes that occur during exercise.

“During exercise, free radicals such as nitric oxide and carbon monoxide are generated that are highly damaging to organs, cells, and DNA,” explained Elena Vara, PhD, a member of the research team and professor of Biochemistry, from the Faculty of Medicine at Complutense University of Madrid. “In contrast, MSM is known to possess potent antioxidant properties that could potentially interfere with the production of these harmful free radicals.”

To test this hypothesis, Vara and colleagues evaluated the effect of MSM supplementation (with or without the addition of vitamin C, another well-known antioxidant) in 24 competitive jumpers during a 5-week competitive tour.

Horses were randomly divided into one of three groups. The MSM group received 8mg/kg once daily with food, the MSM plus vitamin C group was administered 8 mg/kg MSM and 5 mg/kg vitamin C once daily with food, and the control group, which received their regular diet. Blood samples were collected one day after arriving at the show ground, prior to exercise, and again 10-15 minutes after their competition.

The blood samples were analyzed for various measures of oxidation including nitric oxide and carbon monoxide levels and the activity of various cellular antioxidant enzymes that function to control the production of free radicals in the body.

“Our results identified significant increases in both nitric oxide and carbon monoxide, but reduced antioxidant enzyme activity levels, indicating that the normal antioxidant mechanisms were overwhelmed in these athletic horses,” said Vara.

In the horses supplemented with MSM, all of these deleterious exerci