Is Your Horse Getting Enough Vitamin E? Signs, Benefits & Best Sources

Vitamin E for Horses: Why It Matters, Signs of Low Levels, and Choosing the Right Supplement

Vitamin E is one of those nutrients that doesn’t always get the spotlight… until a horse starts feeling flat, tight through the muscles, or is recovering slower than expected. In simple terms, vitamin E helps protect your horse’s cells from oxidative damage, and that matters whether you’ve got a high-performance athlete, a growing youngster, a broodmare, or a paddock pet.

Let’s break down what vitamin E does, why deficiencies are common in modern feeding, the difference between natural vs synthetic vitamin E, and where products like Kohnke’s Own Mag-E, Advanced Feeds Advanced E, and Virbac WHITE-E can fit into a feeding plan.

What vitamin E actually does (and why horses need it)

Vitamin E is best known as an antioxidant. That means it helps neutralise “free radicals” — unstable molecules that increase during normal metabolism, and increase even more during exercise, stress, illness, transport, heat, and recovery.

In the horse’s body, vitamin E has key roles in:

• Muscle function and recovery (helping protect muscle cell membranes)

• Nerve health (particularly important in some neuromuscular conditions)

• Immune system support (helping the body respond to immune challenges)

Advanced Feeds describes vitamin E as a proven biological antioxidant with an important role in maintaining muscle membranes and supporting immune function. (Advanced Feeds)

Why vitamin E deficiency is so common

Here’s the big one: fresh green pasture is the richest natural source of vitamin E. But many horses today are:

• on dry pasture for part of the year,

• yarded/stabled for long periods,

• fed mostly hay, or

• eating feeds that have been stored for months.

Vitamin E levels in forage drop with drying and storage, so even a “good looking” hay diet can be relatively low in vitamin E compared with grazing fresh grass.

That’s why vitamin E supplements are so commonly used for horses in work, horses on hay-based rations, and horses that don’t have consistent access to green feed.

Signs your horse might be low in vitamin E

Not every horse shows obvious symptoms, and blood testing is the best way to know. But practical “this makes me suspicious” signs include:

• poor topline development despite good calories/protein

• muscle soreness, stiffness, or slower recovery after work

• low energy / “flat” performance

• reduced immune resilience (getting knocked around by stressors)

• in more serious or specific cases, neurological signs (always vet territory)

If you’re seeing persistent muscle or nerve-type issues, it’s worth talking to your vet about blood testing rather than guessing.

Natural vs Synthetic Vitamin E: what’s the difference?

This is the question that comes up constantly, and it’s a good one.

1) The chemistry in plain English

• Natural vitamin E is typically listed as d-alpha tocopherol (or RRR-alpha tocopherol).

• Synthetic vitamin E is typically listed as dl-alpha tocopherol (or all-rac alpha tocopherol), often as an acetate form for stability.

2) Absorption and “bang for buck”

Research and industry summaries commonly report that natural-source vitamin E is more bioavailable than synthetic forms in horses — meaning more of it ends up in the bloodstream for the same IU dose. 

3) So… which should you choose?

• If you’re aiming for maintenance and your horse is generally thriving, a stabilised synthetic vitamin E in a balanced supplement can be totally reasonable.

• If you’re trying to raise blood vitamin E levels (therapeutic support, harder work, poor pasture access, or higher needs), natural-source vitamin E is often preferred because it tends to be more effective per IU. 

A simple way to think about it: synthetic can maintain; natural often moves the needle faster (though every horse and feeding program is different).

How the featured products fit into the real world

Kohnke’s Own Mag-E (Magnesium + Vitamin E + B1)

If you’ve got a horse that’s a bit busy in the brain or tight through the body (especially around work, travel, or competing), you’ll often see people look at magnesium first — but Mag-E isn’t just magnesium.

Kohnke’s Own notes that Mag-E includes vitamin E and thiamine (vitamin B1) to benefit nerve and muscle function, alongside its magnesium component. (Kohnke's Own)

Where it can make sense:

• horses that get tense in new environments

• horses in work where you want a combined “muscle + nerve” support approach

• horses whose diet is mostly hay and hard feed (limited fresh pasture)

Keep in mind: Mag-E is not a “mega-dose vitamin E therapy product” — it’s more of a multifunction support supplement where vitamin E is part of the package. (Kohnke's Own)

Advanced Feeds Advanced E (a straightforward, cost-effective vitamin E option)

Advanced Feeds positions Advanced E as an oral stabilised vitamin E supplement, designed for situations like strenuous exercise, limited green feed, or long storage of feed. (Advanced Feeds)

They also provide an example dose: 15 g daily provides 1000 IU of vitamin E (with vitamin E listed as d,l alpha-tocopherol acetate). (Advanced Feeds)

Where it can make sense:

• performance horses needing reliable daily antioxidant support

• horses on dry feed/hay for long stretches

• owners wanting a simple vitamin E product that’s easy to add into the bucket

Virbac WHITE-E (natural vitamin E antioxidant support)

Virbac describes WHITE-E as a natural antioxidant for use in horses, beneficial for horses fed vitamin E deficient diets and those prone to muscle stiffness (and also mentions breeding animals). (au.virbac.com)

Where it can make sense:

• horses needing stronger antioxidant support

• horses in harder work or recovery phases

• owners specifically seeking a natural-source vitamin E approach (au.virbac.com)

A quick safety note: vitamin E, selenium, and “stacking” supplements

Vitamin E often gets paired with selenium in some products, and selenium is a nutrient you don’t want to double up accidentally. If your horse is already on a fortified feed, plus a vitamin E/selenium product, plus another balancer… it’s easy to overshoot.

Bottom line

Vitamin E is one of the most important “quiet achievers” in a horse’s diet — especially when pasture is limited and workloads (or stress) increase. Choosing between synthetic vs natural vitamin E comes down to whether you’re aiming to maintain or actively raise vitamin E status, and which format best suits your horse.