Feed Materials In Focus – Is Feeding Corn Oil Good for Treating or Preventing Equine Gastric Ulcers?



The idea of feeding corn oil to horses with gastric ulcers goes back to a paper published in 2004 by Cargile et al. This paper is actually open access so you can read it for free (see bottom of post). However, these authors likely got the idea from a 1987 study in rats which showed that feeding oil to rats prevented experimentally induced peptic ulcers (Jayaraj et al., 1987). 

Cargile et al. (2004) found that 45ml of corn oil a day for 5 weeks decreased gastric acid secretion in response to stimulation of acid secretion with a drug that mimics the action of the hormone gastrin (which stimulates gastric acid secretion in the body under normal conditions). The study was also weak and poorly designed as it only used 4 ponies and the order of treatments was not randomised. The problem with this study is that the authors did not gastroscope the horses to look for gastric ulcers. However, this does not seem to have stopped people promoting 45ml of corn oil a day for horses with gastric ulcers. 

In contrast, Frank and Andrews group at the University of Tennessee published a significantly more robust study in 2005 (Frank et al. 2005). In contrast, this study used a very robust experimental design and 8 horses (6 weeks feeding in a 4 X 4 Latin square randomised crossover design with 5-week washout intervals). The 4 treatments were: 240ml per day of 1) water; 2) refined rice bran oil; 3) crude rice bran oil; 4) corn oil. These doses were chosen based on the studies in rats (Jayaraj et al., 1987) and scaled up for the size of a horse. At the end of each feeding period they induced gastric ulcers by feed deprivation – a valid model. More importantly in this study they gastroscoped the horses to look for ulcers. 


Corn oil is a highly processed and very cheap oil. Processsing involves: 1) cleaning, grinding, and milling; 2) rolling; 3) heating; 4) pressing (at very high pressures); extraction with solvents (e.g. hexane – a carcinogen and skin irritant); 5) boiling to remove the solvent (~90% removed); 6) adding alkalis which form a soap which is mostly removed; 7) washing; 8) drying; 9) heating and adding phosphatide gums, most of which are precipitated out; 10) bleaching or freezing; 11) heating; 12) adding citric acid to inactivate trace metals e.g. lead, cadmium, etc; 13) packing. 

Compare this with cold pressed linseed oil: 1) cleaning, grinding, and milling; 2) pressing; 3) packing. 

Corn oil is one of the highest in inflammation-promoting Omega 6 fatty acids and very low in anti-inflammatory Omega 3 fatty acids. The only thing corn oil has going for it is that it’s relatively low in saturated fats. Bottom line? I would never feed corn oil to horses. 


  • 45ml of corn oil in one poorly designed and very small study (4 animals) slightly decreased gastric acid secretion in ponies. This study did not scope the stomachs.
  • In a larger and properly designed study, feeding 240ml per day of refined rice bran oil or crude rice bran oil or corn oil for 5 weeks had no effect on gastric ulceration.
  • There is no value to feeding corn oil to horses. It is highly processed and is one of the highest in inflammation-promoting Omega 6 fatty acids and very low in anti-inflammatory Omega 3 fatty acids.
  • At the present time the only value of feeding oil to horses with gastric ulcers is if it is used to replace starch i.e the benefit is removing starch from the diet, not adding oil.
  • If you are going to feed oil to your horse then the best thing you can feed is cold pressed linseed oil balanced with added Vitamin E.


Jayaraj AP, Tovey FI, Clark CG, et al. (1987) The ulcerogenic and protective action of rice and rice fractions in experimental peptic ulceration. Clin Sci (Lond); 72:463–466.  


Cargile JL, Burrow JA, Kim I, Cohen ND, Merritt AM. (2004) Effect of dietary corn oil supplementation on equine gastric fluid acid, sodium, and prostaglandin E2 content before and during pentagastrin infusion. J Vet Intern Med. Jul-Aug;18(4):545-9. 


Frank N, Andrews FM, Elliott SB, Lew J. (2005) Effects of dietary oils on the development of gastric ulcers in mares. Am J Vet Res. Nov;66(11):2006-11.  



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