SmartPak Monday Morning Feed: Demystifying Vitamin E

Dr. Gray explains!

Courtesy of

Courtesy of

From the SmartPak blog:

My vet recently told me that my horse should be on a Vitamin E supplement since he has no access to pasture. I went online to research my options but now I’m SO confused! There seem to be a lot of different forms of vitamin E, how do I know which one is best? Some forms claim higher bioavailability than others, but what does that even mean? Thanks for helping me sort this out! – CA

You’re not alone; many people find vitamin E to be one of the most confusing nutrients. Let’s start with the basics. Vitamin E is included in the category of fat-soluble vitamins along with A, D, and K. These four vitamins require fat for them to be absorbed from the digestive tract, and are stored in the liver and fatty tissues.

Like vitamin A, the body does not make any vitamin E, meaning all of it has to come from the diet. Vitamin E is expressed in terms of “activity,” and the NRC or National Research Council recommends 1 International Unit (IU) of vitamin E per kilogram of horse bodyweight. So a 500 kg horse (1100 pounds) would need at least 500 IUs/day of vitamin E. While the upper safe diet limit has been set at 1,000 IU/kg dry matter (that’s 10,000 IU/day for an 1100 lb horse), no signs of vitamin E toxicity have yet been reported even at high intakes.

Vitamin E is an antioxidant that works closely with selenium and vitamin E to protect cells from excess free radicals or oxidative stress. While every horse needs vitamin E, certain conditions have been associated with a deficiency of vitamin E or as requiring more vitamin E than normal such as Equine Motor Neuron Disease and EPM.

Found in high amounts in fresh pasture, levels of vitamin E begin to deteriorate the moment forage is cut for hay. Therefore, horses that do not have access to grass or a full serving of fortified grain should receive vitamin E supplementation, as your vet recommended for your horse.

What else did Dr. Gray have to say about Vitamin E? Click here to read the rest of her response.

Don’t forget to check the SmartPak Blog for more great articles about horse health and more! Go SmartPak, and go riding.

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