Which is Better: Natural or Synthetic Vitamin E?

A veterinarian explains the differences between the two forms of vitamin E and how to determine which is best for your performance horse.

Q: My veterinarian recently suggested I put my mare on a vitamin E supplement since she has very limited access to pasture. After doing some research, I learned there are different forms of vitamin E and some claim to have higher bioavailability. Can you explain what this means and what type is best for horses?

— Betsy H., New Mexico

A: Vitamin E can be a confusing nutrient for many horse owners due to its various forms, multi-faceted health benefits and because individual horses metabolize the nutrient at different rates. For a quick refresher on the basics, vitamin E is an antioxidant that plays a crucial role in maintaining equine health, particularly in supporting the immune system. It does this by protecting immune cells from oxidative stress, boosting antibody production and reducing inflammation.

Horses cannot synthesize vitamin E on their own, so it must be obtained through their diet, primarily fresh forage. Supplementation might be necessary when access to quality pasture is limited. ©Amy K. Dragoo

A proactive approach to vitamin E nutrition can make a significant difference in a horse’s ability to resist disease, recover from injury and maintain optimal health and can be especially beneficial for those under stress or recovering from illness.

Like vitamins A, D and K, vitamin E is fat-soluble meaning that horses cannot synthesize it on their own, and it must be obtained from their diet, primarily through fresh forage. Therefore, when access to quality pasture is limited, ensuring adequate intake through diet or supplementation is a priority for horse owners, trainers and veterinarians alike, especially considering its profound impact on the immune system, muscle function and overall vitality of the horse.

Forms of Vitamin E

Whether you opt to give your horse a powder, pellet or liquid vitamin E supplement, there are two primary forms of the nutrient: natural and synthetic.

Natural vitamin E is listed on an ingredient or feed label as “d-alpha-tocopherol” or the tocotrienols, without the “l.” This is the most bioavailable form of the nutrient, meaning it is absorbed and utilized more efficiently by the horse’s body. Natural vitamin E supplements are often recommended for horses with higher needs, such as those in intense training or those recovering from illness.

Elevate’s Maintenance Powder provides horses with a source of natural vitamin E. It’s also available in liquid form. Courtesy KPP

Synthetic vitamin E will be listed as “dl-alpha-tocopherol,” or some variation starting with a “dl.” While this form is more commonly found in feeds and supplements, it is less bioavailable than the natural form (it’s not absorbed or utilized as efficiently as natural forms). However, it can still provide adequate levels of the nutrient when administered in higher doses.

There are also differences in how the horse’s body absorbs the two forms. Natural vitamin E seems to bind better to specific transport proteins in the liver, which enables the nutrient to be delivered to other tissues. Synthetic forms are excreted faster than natural ones, and therefore don’t have as much time to reach the tissues where they are needed. In other words, a horse must consume more of the synthetic form to achieve the same levels in the bloodstream as the natural form.

Is Natural or Synthetic Vitamin E ‘Better’?

There’s been much debate regarding whether to supplement with natural or synthetic products, and many people swear by one or the other. Some research has suggested that natural vitamin E outperforms synthetic forms when it comes to minimizing oxidative and muscle cell damage in exercising horses. While powdered synthetic vitamin E is typically a mixture of vitamin isomers, some of which are more bioavailable than others.

Synthetic vitamin E is often added to many horse feeds and supplements because it’s less expensive. Natural products are usually about twice that of a synthetic product. Either way, you will get about the same effect at a similar cost.

Synthetic vitamin E is often added to many horse feeds and supplements because it’s less expensive. ©Alana Harrison

With either form, absorption can be improved by adding fat to your horse’s grain ration. Fat binds with vitamin E and helps carry it across the intestinal wall and into the bloodstream. Researchers have also explored other methods to improve absorption. Some products contain “micellized” vitamin E, which means it has been chemically changed to improve absorption. Another approach is called nanodispersion, which separates the nutrient into tiny droplets that disperse across a wider range of the intestinal wall. Both methods have been shown to aid absorption.

Takeaway

To ensure horses receive enough vitamin E, owners and caretakers must pay close attention to their diets. Fresh pasture is the best natural source rich in the nutrient. However, horses that are on restricted grazing or those that primarily consume hay may require supplementation.

The National Research Council recommends that horses consume 1-2 international units (IU) per kilogram body weight of vitamin E daily. This equates to 500-1,000 IU for a 1,100-pound horse. Higher levels may be recommended for horses in hard work or those with certain health issues.

Due to the many variables that affect individual vitamin E levels in horses, establishing a baseline blood vitamin E level is important to determine whether your horse is deficient. If he is, work with your veterinarian to determine the appropriate supplement for him and to recheck his levels after supplementation to ensure they’re not too low or too high. From there, your veterinarian can advise you on making any necessary adjustments to his supplement dosage.

About Tania Cubitt, PhD

Courtesy Tania Cubitt, PhD

A native of Queensland, Australia, Tania Cubitt, PhD, received a bachelor of science in animal science at the University of Queensland before receiving her master of science degree in equine nutrition and growth at Virginia Tech University. She went on to receive her doctor of philosophy degree in equine nutrition and reproduction also at Virginia Tech. Cubitt currently works as an equine nutrition consultant at Performance Horse Nutrition and focuses on developing feeding strategies for horses with special needs.

For More:

  • Learn how vitamin E can help support your horse’s immune system here.
  • To help determine if your horse needs supplementation throughout the winter, click here.

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