Why Vitamin E Matters — Especially for Endurance Horses

If you've spent any time diving into horse nutrition, you've probably come across vitamin E. It's one of those nutrients that's essential for all horses, but it's especially important for endurance horses working at higher levels. Why? Because vitamin E is a powerful antioxidant that helps protect muscles and other tissues from the stress and damage that can occur during long, intense efforts. Basically, it's a key player in keeping your horse feeling good and recovering well.

Vitamin E supports:

• Muscle function and repair

• A strong immune system

• Healthy nerve function

  
  

For endurance horses, that means better performance, faster recovery, and fewer niggles after a tough ride.

Natural vs. Synthetic Vitamin E — What’s the Difference?

Here’s where things can get a bit science-y. There are two main forms of vitamin E used in supplements:

• Natural vitamin E (listed as d-alpha-tocopherol or RRR-alpha-tocopherol): This is the most bioavailable form, which means your horse can absorb and use it more efficiently.

• Synthetic vitamin E (dl-alpha-tocopherol): This one’s cheaper to produce but not as easily absorbed. Your horse needs a bigger dose to get the same benefit.

So, while synthetic forms can work, natural vitamin E is usually the better bang for your buck — especially if your horse has higher needs.

Where Do Horses Get Vitamin E Naturally?

Fresh grass is the best natural source of vitamin E. However, once grass is cut, dried, and stored as hay or haylage, vitamin E levels drop significantly. So if your horse is on restricted grazing, eating hay all year round, or in hard work, they might not be getting enough.

Bucket feeds and balancers often contain added vitamin E too, so it’s worth checking the label. Performance feeds usually provide higher levels to support muscle function and recovery in hardworking horses — but the exact amount can vary, so always look closely at what's listed.

That’s why so many endurance riders (and vets) recommend topping up with a supplement.

Why Supplementing Might Be Necessary

Even a well-balanced diet might fall short — especially if:

• Your horse is in full or regular work

• You feed mostly hay or haylage

• You’re managing a horse with muscle issues (like tying up)

• You have limited turnout on good grass

Topping up with a quality vitamin E supplement is a simple way to support muscle health, recovery, and overall wellbeing — especially when you're asking a lot from your horse.

Can You Feed Too Much Vitamin E?

Vitamin E is a fat-soluble vitamin, which means it’s stored in the body rather than excreted quickly like water-soluble vitamins. That said, horses tolerate fairly high levels well, and toxicity is rare. Still, there’s no need to go overboard — more isn’t always better.

Most horses won’t need more than 5,000 IU per day unless under veterinary guidance.

Always consider what your horse is already getting from their base diet and any other supplements to avoid unintentional over-supplementation.

If in doubt, speak to your vet or a qualified nutritionist — especially if you're using multiple products that contain vitamin E or selenium.

What About Selenium?

Selenium is another antioxidant that works closely with vitamin E to support muscle function and the immune system. Most vitamin E supplements also contain selenium — but be cautious about doubling up.

Too much selenium can be toxic. The safe upper limit is considered to be around 3mg per day for an average 500kg horse. Make sure to check your feeds, balancers, and any other supplements to avoid accidentally exceeding this.

If you're feeding a separate selenium supplement or a vitamin E & selenium combo, it’s definitely worth doing the maths — or better yet, have a nutritionist help.

Vitamin E Supplement Comparison Table

To help you navigate the options, here’s a comparison of some popular supplements. Be sure to check whether they’re BETA NOPS approved if you're competing!

If you're unsure how much your horse needs, or whether to choose a combined vitamin E and selenium supplement, speak to your vet or a qualified equine nutritionist.

And remember — if you found this breakdown helpful, it took a lot of spreadsheets and coffee ☕ so feel free to buy me one!