Feed Materials In Focus – The Safety of Feeding Linseed/Flaxseed to Horses



There has recently been an increasing amount of hysteria concerning the risk of feeding linseed/flaxseed to horses due to “speculation” over the risk of cyanide poisoning. Some of this has been fuelled by a recent publication by the European Food Standards Agency and irresponsible, misleading, inaccurate and ignorant posts by a number of companies. 

FACTS (not speculation or hysteria) 

1) Linseed contains compounds called cyanogenic glycosides (CG). These are not toxic. 

2) The seeds contain an enzyme called Linamarase. 

3) Linamarase breaks down CGs to cyanohydrins.

4) When the seeds are crushed and in the presence of water and at a pH above 5, CGs can be broken down to cyanohydrins and then to hydrogen cyanide. 

5) Boiling or micronising prevents the enzyme from working = no hydrogen cyanide. 

6) Acidity in stomach prevents the breakdown of cyanohydrins = no hydrogen cyanide. 

*** Boiling or micronising of linseed  will not result in any production of hydrogen cyanide *** 

***The acidity in the horse’s stomach will also prevent the production of hydrogen cyanide *** 

*** Linseed oil does not contain water, cyanogenic glycosides or linamarase = No risk of hydrogen cyanide production *** 

It’s not desirable to feed linseed raw as it has lower digestibility as the seeds are small and many will not be ground open. However, the risk of hydrogen cyanide production is very low as once the linseed reaches the stomach the low pH (acidity) prevents the breakdown of cyanohydrins to hydrogen cyanide. 

The only risk of hydrogen cyanide production with linseed is with uncooked linseed if you crush it and leave it, especially in water, at a warm temperature for a significant length of time before feeding it to your horses. 

Professional equine nutritionists are unaware of any documented cases of cyanide poisoning in horses from feeding cooked linseed/flaxseed. Also please remember, horses have been fed cooked linseed for hundreds of years with no documented cases or even suspicion of cyanide poisoning. 


Cooked (boiled/micronised linseed/flaxseed) presents no risk to horses. Please don’t listen to people who have no real knowledge or understanding of equine nutrition. Please trust and respect equine nutrition professionals on this. 


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