When to Supplement Vitamin E

The Role of Vitamin E

Vitamin E is a fat-soluble vitamin that plays a key role as an antioxidant. Antioxidants help neutralise harmful free radicals, which are unstable molecules that can damage body cells through a process called oxidative stress. The production of free radicals increases during periods of intense exercise, illness, injury, or any form of physical stress, which increases the body’s need for antioxidant support. Vitamin E is also essential for the proper functioning of the immune system, as well as cardiovascular, circulatory, neuromuscular, and reproductive health.

The Importance of Grass

When healthy horses are given frequent access to fresh good quality pasture, vitamin E requirements are likely to be met. Horses require green grass for at least 12 hours per day for 6 months out of the year to retain their vitamin E stores. However, this level of pasture access is often not possible, with many horses receiving hay or haylage as their predominate forage source. Immediately after forage is cut for conservation, vitamin E levels start to decline, resulting in levels 20-80% less than fresh grass. Grass quality also declines over winter months, so access to plenty of fresh spring and summer grass is key. 

Due to the variable vitamin and mineral levels in hay and grass, it is important for all horse’s to be managed on the recommended rate of a fully fortified feed or balancer, to ensure nutrient requirements are met year-round. For most horses, the antioxidants they get in their grass and hard feed is enough to neutralise free radicals. However, some horses benefit from additional vitamin E supplementation such as horses with restricted pasture access, performance horses undergoing intense exercise, breeding stock, horses with neurological or neuromuscular problems, following stressful events such as weaning or travel, or following injury or illness to support recovery. 

When is Vitamin E Supplementation Beneficial

For performance horses in a moderate to high workloads, vitamin E’s role as an antioxidant is increasingly important in protecting tissues and cells from free radical degradation. During exercise, the body uses more oxygen to create energy, producing small amounts of free radicles as a natural byproduct. During intense or prolonged exercise, these reactions occur quicker, leading to a greater accumulation of free radicals than the body can easily manage. These excess free radicals cause damage to cell membranes throughout the horse’s body, often leading to muscle stiffness and soreness in horses without sufficient vitamin E stores. Maintaining adequate vitamin E stores helps counteract this oxidative stress, supporting muscle health and overall performance. 

Free radical production is also increased during injury and illness, as the body’s immune system generates them to destroy damages cells and pathogens. Whilst this process is a necessary part of the immune response, the body enters a state of increased oxidative stress, potentially leading to secondary tissue damage. For horses with an acute, one-off injury or illness bout, vitamin E can just be supplemented through the recovery period. For horses with a condition that affects them long term such as a muscle myopathy or neurologic condition, it is beneficial to supplement with vitamin E consistently. Working collaboratively with your vet and nutritionist is key to determine how much additional vitamin E your individual horse needs. 

Vitamin E also has the potential to positively influence fertility in broodmares and improve the passive transfer of antibodies through colostrum. Supplementing mares with additional vitamin E at a rate of 2500iu per day during the last four weeks of pregnancy has been shown to increase levels of key antibodies for immunity, IgG and IgM, in the mare’s milk in the first three days after birth, as well as increasing her serum levels of vitamin E. The same effect was seen in the foals, having elevated serum vitamin E and IgM levels, supporting early immune function.

Vitamin E Deficiency

Vitamin E deficiency in horses can cause a variety of symptoms including poor immunity, weight loss, muscle atrophy, difficulty with balance and coordination, stiffness, and chronic fatigue. For some horses the signs can be severe whereas others will be more subtle. Long term deficiency can result in neuromuscular disease, with Equine Degenerative Myeloencephalopathy typically affecting young horses (5 months to 3 years), vitamin E Responsive Myopathy in middle aged horses, and Equine Motor Neuron Disease most commonly in older horses with long term deficiency. Identifying signs of deficiency and quickly increasing vitamin E levels is key but ensure to work with your vet to rule out other potential causes first.

Selecting a Vitamin E Supplement

When looking at vitamin E supplements for horses, it is important to note that natural sources are far more potent than synthetic forms. 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. 

Controlled studies at Kentucky Equine Research indicate that the liquid, natural vitamin E supplement for horses, Nano-E® is superior to synthetic and other natural vitamin E sources. The vitamin E in Nano-E® is encapsulated in nanoparticles and surrounded by a hydrophilic (water-loving) outer layer, allowing it to be rapidly and evenly released in water-based environments, such as the gastrointestinal tract. This unique delivery system increases the bioavailability of vitamin E, optimising the amount that is absorbed into the bloodstream. Sufficient rates of a natural liquid supplement can increase serum levels effectively in 2-3 days making is the most effective option and particularly important for horses recovering from neuromuscular disease. With 250iu per 1ml of Nano-E®, the daily rate can be adjusted depending on the individual horse’s requirements. Click here to read more about Nano-E®. 

Assessing Vitamin E Status

It is possible to test your horse’s vitamin E levels via a blood sample. This can be beneficial to identify whether supplementation is necessary and how effective supplementation has been at raising the bodies vitamin E stores. The test provides additional detail to guide your vitamin E supplementation protocol, but the real indicator is your horse’s clinical signs. Some horses may require higher serum vitamin E levels than others to keep them free from clinical signs, so it is important to monitor your horse as an individual and identify which level of vitamin E supplementation works best for them.