The Benefits of Feeding Flax

Even fans of feeding flax may not realize all its benefits.  It’s a very healthful supplemental feed item for horses of all ages, classes and uses.

People usually feed flax for its high omega-3 fatty acid content. There are two classes of fatty acids (the building blocks of fats) that must be in the diet, omega-3 and omega-6. Both are essential for peak immune function and the omega-3s contribute to normal homeostatic balancing of inflammatory reactions. Whole flax seeds are 30+% fat with the same high omega-3 profile as fresh grass.  There are visible benefits to coat, skin and hooves. Omega-3s also support vision, the nervous system, development of young animals and keep all the cells’ membranes pliable.

At about 25% protein, flax seeds are also an excellent protein supplement with some key specific benefits. They are a good source of the most commonly deficient amino acid, lysine, and contain even higher levels of leucine which is the most common amino acid in skeletal muscle. It’s also a very good source of methionine, the sulfur containing amino acid that is becoming increasingly scarce.  In fact, it is close to meeting the specifications for equine “ideal protein” as set forth by Bryden.

On the mineral end, flax seeds have 2 to 4 times more magnesium than hays. The calcium:phosphorus ratio is reversed at just a little under 1:2 but this complements alfalfa and most grass hays as well. Unlike hays, on average flax seed is low in manganese but has adequate zinc and copper in correct ratios to each other.

If you put flax seed in water you will see it quickly becomes a gel-like, slimy mass. This is because flax seed is very high in soluble fiber, mucilage.  Soluble fiber is a safe source of calories and is prebiotic because it is very easy to ferment. It can also be mixed with psyllium to aide in physical removal of sand from the intestinal tract.

The simple sugar and starch levels in flax seed are low and safe for insulin resistant/hyperinsulinemic animals.

Some people fear flax because they have heard it can cause cyanide poisoning. This fear is largely unfounded.  Flax seeds contain cyanogenic glycosides, compounds that can be metabolized by beta-glucosidase enzyme to release cyanide.  Cyanogenic gylcosides are found in about 2000 different plants with high levels in some common foods, like lima beans, barley and sorghum. They are a defense mechanism. When insects feed on the plant or seeds they bring the enzyme and cyanide precursors into contact and release cyanide.

Like all toxins, there is a dose effect. The horse ingests a variety of potential toxins from various sources every day but the body can handle these low level exposures with no difficulty. It’s only when high levels overwhelm normal day to day protection processes that problems occur.

The two most important things to remember about cyanide and flax are that 1) no case of mammalian cyanide toxicity caused by flax ingestion has ever been reported and 2) cyanogenic glycosides are only high in green immature seeds, dropping to trace in mature brown or golden seeds.

Soaking in water for short periods will create the highest levels of cyanide because it allows the enzymes in the seeds to come in contact with the precursor cyanogenic glycosides. Boiling is safe because hydrogen cyanide is a gas and will evaporate off. However, mature seeds can be fed whole or ground safely with no boiling or other processing.

Flax seed has been fed by many generations of horse caretakers and for good reason. It is a safe source of calories with high levels of omega-3 fats and protein, benefiting the immune system, coat, skin, hooves, muscle, nervous system and all cell membranes.

Eleanor Kellon, VMD



About Dr. Kellon

Graduate of University of Pennsylvania Veterinary School. Owner of Equine Nutritional Solutions,, industry and private nutritional consultations, online nutritional courses. Staff Veterinary Expert at Uckele Health and Nutrition.
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5 Responses to The Benefits of Feeding Flax

  1. H.B.D. says:

    Dr. Kellon, You’ve mentioned in this article “mature seeds can be fed whole or ground safely with no boiling or other processing” Is there a benefit to grinding the flax? Can the horse get all the added benefits if the flax is not ground? I was under the impression it had to be ground. I would be so relieved if I could feed it without grinding it fresh every day as I have been! Thanks, H.B.D.

    • Dr. Kellon says:

      The horse can probably derive some benefit from whole flax but it is much better to grind the flax so that digestive enzymes can gain access to the fats and protein in the interior. Remember seeds are designed to survive the digestive tract. It’s one way plants spread.

  2. Dear Dr. Kellon:
    I can’t ask my question (which you answered some time ago and I lost the reference) without saying “thankyou.” I don’t know where I would be without all your help.
    Your article on “Loving Mares?” You gave me the image of what I have been working towards. That image helped me get there, when everyone has been telling me it couldn’t be done (and without your insights, it would never have been).
    So, what is your recommended amount of flax to feed?

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