Question

My Arabian gelding travels from show to show for many weeks from midsummer to early fall. During this time, he has little chance to graze. The equine nutritionist that oversees my horse’s diet suggested I give my gelding supplemental vitamin E while he’s on the road. Why?

Answer

Let me offer praise for consulting with an equine nutritionist. Horse owners seek the advice of veterinarians and farriers without hesitation, but many still do not see the value in nutritional consultation. Your horse is benefitting from your diligence on that front.

Vitamin E functions as a biological antioxidant, preventing the oxidation and peroxidation of polyunsaturated lipid materials in cellular and subcellular membranes by neutralizing the production of free radicals, which can potentially weaken cells and tissues if left unchecked. Its antioxidant effects are beneficial throughout the body but particularly for nerve and muscle function. Therefore, it is a critically important nutrient for all horses, but is especially important for exercise.

Vitamin E levels in fresh, good-quality pasture far exceed those in good-quality hay and concentrates. When your gelding is on the road consuming just these “preserved” dietary components, he is likely not receiving sufficient vitamin E. To keep antioxidant status at its peak, supplementation with vitamin E is essential.

Vitamin E supplements can be separated into two categories, synthetic and natural. Research has revealed that vitamin E varies in its potency, based on whether it is natural or synthetic, namely because the chemical structure of each is different. Natural vitamin E is recognized as “d-alpha-tocopherol,” and is made up of a single isomer. Synthetic vitamin E, termed “dl-alpha tocopherol,” contains a mixture of eight different isomers, four tocopherols and four tocotrienols. Of these eight, only one is molecularly equivalent to natural vitamin E. Therefore, natural vitamin E is preferable.

To make vitamin E stable in supplements, it must be chemically joined with an alcohol during manufacture, a process called esterification. The alcohol, often acetate, acts as a padlock that protects the vitamin E from the damages caused by exposure to oxidative forces. Without esterification, vitamin E can quickly denature, losing its antioxidant properties and rendering it ineffective.

Once ingested, esterified alpha-tocopherol is subjected to normal digestive enzymes. A certain group of enzymes called esterases are chemically capable of unlocking the padlock created through esterification. Once free, vitamin E is available for absorption with its antioxidant properties intact.

A two-part study at Kentucky Equine Research compared the bioavailability of synthetic and natural-source vitamin E, and then evaluated the bioavailability of two water-soluble forms of natural vitamin E, micellized and nanodispersed (into liposomes). As predicted, both water-soluble forms of natural vitamin E were significantly more bioavailable than synthetic vitamin E. Relative to the synthetic form, bioavailability of micellized and nanodispersed forms were 559% and 613%, respectively.

For the best protection, choose a natural-source, water-soluble form of vitamin E, such as Nano•E, for horses like yours that have little or no access to fresh, green pasture.