Why Your Horse Needs Vitamin E

 All this activity not only damages the molecules that have their electrons stolen, it may inhibit their ability to do their jobs within the body. If there are too many free radicals present in the tissue, this chain reaction can run out of control and injure cell walls, DNA and other vital structures.

Free radicals are a natural byproduct of the utilization of fats, carbohydrates and proteins as fuel. They do have beneficial functions; they can help neutralize bacterial or viral threats, for example. But when the number of free radicals in the tissues climbs too high—such as in the muscles after a horse exercises—the body deploys antioxidants to bind with them, breaking the cascade.

In the case of vitamin E, action centers on the fats that form the structure of cell membranes, where the nutrient remains ready to bind with free radicals that might otherwise damage the cell walls. “It helps protect the cells,” says Carey Williams, PhD, an equine extension specialist with Rutgers, the State University of New Jersey. “The vitamin E incorporates itself into cell membranes and protects them from oxidative damage.”

A shortage of vitamin E might mean more oxidative damage occurs in cells throughout the body, including those in muscles, nerves and immune cells. In the case of a hardworking horse, outward signs of oxidative injury might be muscle soreness and a slower-than-expected recovery from exercise. And so, when a horse’s workload increases, his need for antioxidants, including vitamin E, also goes up.

“When you damage muscle, for any reason, you have some oxidative stress,” says Paul Siciliano, PhD, of North Carolina State University. “In the cell, when metabolism is taking place, some pro-oxidants are produced. You could equate it to a campfire out in the woods. The fire is producing heat energy and it might send up sparks in the process. As long as the sparks get put out, things are fine. But if one of them starts another fire and it grows, you could have a problem. Vitamin E attaches to the cell membranes and quenches those little fires and keeps things working properly.”

Oxidative damage is most likely to occur in tissues in the immune system, nerves and muscles, because they are more highly metabolic—that is, they “burn” energy faster. “Thus they produce a greater proportion of these pro-oxidants just as a cost of doing business,” Siciliano says. “There is higher likelihood to have a problem in those areas if horses are short on vitamin E.”

Click here to read about five diseases linked to Vitamin E deficiency in horses.

How much vitamin E does a horse need?

A horse’s requirements for vitamin E have not been well established. “We have defined these requirements only because we know that horses consuming it at a certain level haven’t had any deficiency symptoms,” Siciliano says. Guidelines in the Nutrient Requirements of Horses from the National Research Council (NRC), last revised in 2007, recommend about 500 IU (international units) daily as a maintenance level for an 1,100-pound horse in light work.

This isn’t a lot, so if a horse has access to pasture, that horse has plenty of vitamin E, since green pasture is the best source,” says Williams. “Just like your parents always told you to eat your vegetables—because they contain lots of vitamins—our horses that are out on pasture will have those vitamin needs met.”

Horses who spent the winter foraging on dried grasses draw on their internal stores of Vitamin E.

The NRC recommendations are higher for hardworking horses and for breeding mares and stallions. “Working horses might need up to 1,000 IU per day,” says Williams. “These figures are the minimums, however. There have been many studies, including some I have done, that have shown that more vitamin E is even better. Most of the studies I did looked at supplementing 5,000 IU per day for the average-size horse on a hay diet and not on pasture. These horses had lower levels of muscle enzymes in their blood, which means less muscle membrane permeability or leakage of material into circulation.”