Is Sunflower Oil Poison? What Horse Owners Should Know About Omega 6 and Omega 3

Sunflower oil is widely used in horse feed. It is inexpensive, readily available and an easy way to add calories without increasing the amount of concentrate a horse receives.

But there is something many horse owners never look at:

the fatty acid profile of the oil.

And when you compare sunflower oil with other commonly fed oils, the difference is enormous.

So, is sunflower oil literally poison? No. But its extremely omega 6 heavy composition raises a much more useful question:

Why feed it when there are better balanced alternatives available?

Not all oils are equal

Adding oil to a horse's diet can be useful when extra energy is needed. Owners also commonly feed oil for weight gain or coat condition.

But "oil" isn't one nutritional category.

Different vegetable oils contain very different proportions of omega 6 and omega 3 fatty acids. That matters because these fatty acids don't perform identical roles in the body.

Simply looking at the number of calories therefore misses an important part of the picture.

The problem with sunflower oil

Sunflower oil is particularly rich in linoleic acid, an omega 6 fatty acid, while containing very little alpha linolenic acid, an omega 3 fatty acid.

In the equine research we examined, the contrast was striking:

SUNFLOWER OIL

Omega 3: 0.28%
Omega 6 : Omega 3: 135 : 1

FLAXSEED OIL

Omega 3: 56%
Omega 6 : Omega 3: 0.29 : 1

That is not a small nutritional difference.

It is an entirely different fatty acid profile.

Why does omega 6 matter?

This is where the subject needs some nuance.

Omega 6 isn't inherently "bad." Horses require essential fatty acids, and omega 6 has legitimate biological functions.

However, omega 6 fatty acids are also involved in metabolic pathways that can produce pro inflammatory mediators.

Omega 3 fatty acids, on the other hand, are involved in pathways associated with regulating and resolving inflammatory responses.

That does not mean eating sunflower oil automatically gives a horse an inflammatory disease. Nutrition is more complicated than that.

But it does mean that continually adding a very omega 6 rich oil to an already omega 6 rich diet deserves scrutiny.

Modern horse diets already contain omega 6

This is particularly relevant because horses don't consume oil in isolation.

Their complete diet matters.

Concentrates and cereal based feeds can already contribute substantial omega 6. Adding sunflower oil on top of that can push the fatty acid profile even further towards omega 6 while contributing almost no omega 3 to counterbalance it.

And that's why the question shouldn't simply be:

"Does my horse need more calories?"

It should also be:

"What am I using to provide those calories?"

What you pour into the bucket can reach the horse

This isn't purely theoretical.

Equine studies have shown that changing dietary fat sources can alter fatty acid profiles measured in horses' blood and tissues.

In other words, the fatty acid composition of the diet can be reflected inside the horse.

That makes the choice of oil relevant.

Two oils may provide roughly similar amounts of energy while delivering dramatically different fatty acid profiles.

So, should you feed sunflower oil?

Our answer is simple:

No. We wouldn't choose it.

Not because a spoonful of sunflower oil is going to poison a horse.

But because if you're deliberately adding oil every day, there are alternatives that provide calories with a considerably more favourable omega 3 contribution.

When a better option is readily available, there is little reason to deliberately choose an oil with such an extreme omega 6 to omega 3 profile.

Which oils are better options?

Three alternatives worth considering are:

Flaxseed / linseed oil

Particularly interesting because of its very high alpha linolenic acid, or omega 3, content. Of the oils we examined, this would be our first choice when increasing dietary omega 3 is the objective.

Camelina oil

Another plant oil with substantially more omega 3 than sunflower oil and therefore a very different fatty acid profile.

Canola oil

Contains more omega 3 and a less extreme omega 6 to omega 3 ratio than conventional sunflower oil.

The exact composition can vary according to variety, processing and product, so always check the nutritional information for the specific oil you're buying.

Our pick? Flaxseed oil

The numbers explain why.

In the research used for our comparison, flaxseed oil contained approximately 56% omega 3, compared with just 0.28% in sunflower oil.

That's an extraordinary difference for two products that may both simply be described as "oil" in a feed room.

It doesn't mean every horse suddenly needs flaxseed oil. A horse that maintains weight easily and receives a well balanced diet may not need additional oil at all.

But when you are going to add oil, it makes sense to choose deliberately.

The bigger lesson

Horse nutrition is full of habits that have been passed from stable to stable for years.

"We've always fed it" isn't the same thing as "it's the best choice."

Sunflower oil is a perfect example.

It's cheap. It's convenient. It provides calories.

But those facts tell us nothing about whether its fatty acid profile is what we actually want to add to a horse's diet.

Don't just add oil. Know what you're adding.

And next time you're in your feed room, turn the bottle around and take a closer look at what's inside.

 

SCIENTIFIC SOURCES

The information in this article is based on peer reviewed equine research examining dietary oils, omega 3 and omega 6 fatty acids, and their incorporation into the horse.

Lucarelli et al. (2025), Journal of Animal Science
The effect of dietary camelina, flaxseed, and canola oil supplementation on skin fatty acid profile and immune and inflammatory responses in healthy adult horses.
https://doi.org/10.1093/jas/skaf025

Shoveller et al. (2023), Journal of Animal Science
Effects of dietary camelina, flaxseed, and canola oil supplementation on transepidermal water loss, skin and coat health parameters, and plasma prostaglandin E2, glycosaminoglycan, and nitric oxide concentrations in healthy adult horses.
https://doi.org/10.1093/jas/skad373

O’Connor et al. (2016)
Incorporation of sunflower oil or linseed oil in equine compound feedstuff: Effects on haematology and on fatty acids profiles in the red blood cells membranes.
PubMed PMID: 27080721

Hansen et al. (2002), Journal of Veterinary Internal Medicine
Effects of Dietary Flaxseed Oil Supplementation on Equine Plasma Fatty Acid Concentrations and Whole Blood Platelet Aggregation.
PubMed PMID: 12141309

Nogradi et al. (2005)
Effects of feeding sunflower oil or seal blubber oil to horses with recurrent airway obstruction.
Available through PubMed Central: PMC1635996

Important note: The precise fatty acid composition of an oil can vary according to plant variety, processing and product. The percentages quoted in this article refer to the oils analysed in the cited research and should not be interpreted as the guaranteed composition of every commercially available oil.