The Importance of Vitamin E for Your Horse

Vitamin E is one of those nutrients that can be easy to overlook, but it plays an important role in keeping horses healthy, comfortable and performing at their best. It is especially important for horses with limited access to fresh green pasture, horses in heavy work, breeding horses, young growing horses, senior horses and horses with certain muscle or neurological concerns.

Because vitamin E is not produced by the horse’s body, it must come from the diet. The challenge is that the richest natural source of vitamin E is fresh green grass, and many horses do not have reliable access to quality pasture all year round.

What Does Vitamin E Do?

Vitamin E is a fat-soluble antioxidant. Its main role is to help protect the body’s cells from oxidative damage. This is especially important in tissues with high oxygen demand, such as muscles, nerves and the immune system.

For horses, vitamin E helps support:

• Muscle health and recovery

• Nerve function

• Immune system support

• Exercise performance

• Reproductive health

• General wellbeing

• Healthy ageing

Horses in work naturally create more oxidative stress through exercise. Vitamin E helps protect muscle cells from some of this stress, which is why it is commonly considered for performance horses, horses building topline, and horses prone to muscle soreness or stiffness.

Long-term vitamin E deficiency has also been associated with serious neuromuscular conditions, including equine motor neuron disease and vitamin E-responsive myopathy. These conditions require veterinary diagnosis and management, but they highlight why adequate vitamin E intake matters. 

Where Do Horses Usually Get Vitamin E From?

The best natural source of vitamin E is fresh green pasture. Horses grazing good-quality pasture can often meet their vitamin E needs naturally.

However, vitamin E is not very stable once grass is cut, dried and stored. Hay may still be an excellent forage source, but vitamin E levels decline after harvest and during storage. This means horses on hay-only diets, dry paddocks, sand yards, restricted grazing or summer pasture may receive far less vitamin E than horses grazing fresh grass daily.

This is one of the biggest reasons vitamin E supplementation is commonly considered for horses in Australian conditions, especially where pasture is seasonal, limited, overgrazed or restricted for weight, laminitis or metabolic reasons.

Horses That May Need More Vitamin E

Some horses are more likely to require additional vitamin E support than others. These include:

Grass-restricted horses

Horses kept off pasture due to weight control, laminitis risk, insulin dysregulation, ulcers, injury rehab or property limitations may have lower natural vitamin E intake.

Horses on hay-based diets

Hay is valuable, but it does not provide the same vitamin E level as fresh green pasture, especially after storage.

Performance horses

Horses in regular training, competition or heavy work may benefit from extra antioxidant support due to increased muscle workload and oxidative stress.

Horses building muscle or topline

Adequate vitamin E supports healthy muscle function, particularly when combined with balanced protein, amino acids and overall energy intake.

Senior horses

Older horses may need additional nutritional support to maintain muscle, immune health and general condition.

Breeding horses and growing foals

Pregnant and lactating mares, as well as growing foals, have higher nutritional demands. Vitamin E, often alongside selenium, is important for muscle and immune health.

Horses with muscle concerns

Horses prone to tying-up, stiffness, poor recovery or unexplained muscle loss should be assessed by a veterinarian. Blood testing may help determine whether vitamin E status is part of the picture.

Natural vs Synthetic Vitamin E

Not all vitamin E supplements are the same. One of the key differences is whether the vitamin E source is natural or synthetic.

Natural Vitamin E

Natural vitamin E is usually listed as d-alpha-tocopherol. This is the form most similar to what horses obtain from fresh grass. It is generally considered more bioavailable, meaning the horse can absorb and use it more efficiently.

Synthetic Vitamin E

Synthetic vitamin E is usually listed as dl-alpha-tocopherol or all-rac-alpha-tocopherol. It can still contribute vitamin E to the diet, but it is generally not utilised as efficiently as natural vitamin E.

Research and equine nutrition sources commonly indicate that natural vitamin E is better absorbed and retained than synthetic forms, meaning a horse may require more synthetic vitamin E to achieve a similar blood level response. 

This does not mean synthetic vitamin E has no value. It may still be suitable in some general supplements or fortified feeds. However, for horses with very limited pasture, higher needs, muscle concerns, or known low vitamin E status, a natural vitamin E supplement may be preferred.

Vitamin E and Selenium: Why They Are Often Mentioned Together

Vitamin E and selenium are often discussed together because both act as antioxidants and both are involved in muscle health. However, selenium needs to be managed carefully, as too little can be a problem and too much can be toxic.

This is why it is important not to simply add multiple selenium-containing supplements without checking the full diet. Many feeds, balancers and supplements already contain selenium. If your horse needs vitamin E support, you may not always need extra selenium as well.

If there are concerns around muscle weakness, tying-up, poor performance or deficiency, your veterinarian or equine nutritionist may recommend blood testing before making major changes.

Signs Your Horse May Need Vitamin E Support

Vitamin E status is best confirmed through blood testing, but there are some situations where it is worth reviewing the diet.

Consider vitamin E intake if your horse:

• Has little or no access to green pasture

• Is fed mostly hay or preserved forage

• Is in moderate to heavy work

• Has poor muscle development despite good feeding

• Shows slow recovery after exercise

• Has unexplained stiffness or muscle soreness

• Is a senior horse losing topline

• Is recovering from illness, travel or stress

• Is a broodmare, foal or growing young horse

These signs can have many causes, so vitamin E should be considered as part of the bigger nutritional and veterinary picture.

How to Support Vitamin E Intake

The first step is to look at the whole diet.

A good vitamin E plan may include:

1. Fresh pasture where appropriate
   This is the most natural source, but it is not suitable or available for every horse.

2. Good-quality forage
   Forage should remain the foundation of the diet, even though hay may not provide enough vitamin E on its own.

3. A balanced feed or balancer
   Many fortified feeds provide some vitamin E, but levels vary.

4. Targeted supplementation
   Horses with limited grass access or higher needs may benefit from a dedicated vitamin E supplement. Supplements such as Advanced Vit E, iO Magnesium & Vitamin E,and KER Nano E can be beneficial supplements. 

5. Professional guidance when needed
   For horses with health concerns, blood testing and veterinary advice are recommended.

Vitamin E is essential for muscle health, nerve function, immunity and overall wellbeing. While horses naturally obtain vitamin E from fresh green pasture, many modern management systems limit pasture intake. Horses kept on hay, dry lots, restricted grazing or in regular work may not receive enough from forage alone.

Natural vitamin E is generally more bioavailable than synthetic vitamin E, making it a useful option for horses with higher needs or limited pasture access. However, the right choice depends on your horse’s diet, workload, health status and individual requirements.

If your horse is grass-restricted, in work, building topline, ageing, or showing signs of muscle soreness or poor recovery, it may be worth reviewing vitamin E intake as part of their overall feeding plan.

For tailored advice, speak with your veterinarian or equine nutritionist, and choose supplements that suit your horse’s full diet rather than adding products at random.