Re: Farriers formula and iron overload

lj friedman

This email is from the DVM at Farriers Formula,, concerning iron overload. Any thoughts on this? 

The iron level in Farrier’s Formula Double Strength has been reduced to 222 mg/lb (as fed basis) as tested by an independent lab. An 85 gram serving (1/2 cup, or a 4 fluid oz. measure) will deliver the horse approximately 42 mg of iron in the form of iron oxide.


Iron is not added to any of Life Data’s equine products; however iron oxide is a component of an ingredient that helps condition the pellets. The amount of this pellet conditioner in the product was reduced in mid-2014 to less than ½ of the prior formulation. The pellet conditioner is a natural clay that has been cleaned and  sterilized. This pellet conditioner reduction has not affected the quality of the pellets.


Research has implicated that an excess of absorbable iron in the diet, or iron overload, may be linked to insulin resistance in horses.


More information is needed, such as double blind research studies, on whether iron oxide is indeed broken down in the horse’s gut and absorbed as iron in any significant amounts. Our thoughts and conventional wisdom dictates that iron oxide is tightly bound and is not broken down in significant amounts by gastric juices or microbes in the gut. This logic would also explain why horses living their life on red soils and red sands (i.e. high levels of iron oxide) remain healthy, even following centuries of evolution.


As a comparison, a typical cool season grass hay contains 194 ppm of iron on a dry matter basis. A horse consuming 15 lbs. of this 90% dry matter hay per day would have an intake of 1,189 mg of iron per day, compared to an insignificant 42 mg per day in Farrier’s Formula Double Strength. Add the likely fact that the iron oxide in Farrier’s Formula does not provide absorbable (bioavailable) iron, and forages do provide bioavailable iron, it is apparent that Farrier’s Formula Double Strength is not a significant source of iron to a horse.


Supplements that contain iron sulfate, chelated iron, or iron proteinates do provide absorbable iron – and usually too much of it. Iron proteinates are particularly disturbing – the intestinal wall is absorbing an amino acid but the iron is hitching a ride. Many equine supplements contain these ingredients.


Although adult horses typically have sufficient stores of iron, young growing horses often need additional iron. If iron supplementation is desirable a bio-available source of iron should be utilized. Blood testing for iron status (ferritin, iron binding capacity, etc.) and iron anemia (RBC, reticulocytes, MCV, hypochromasia, etc) can be performed. Of particular interest is that the mare is much like the sow in that iron does not pass the placental barrier readily. Many foals with iron deficiency  are from mares with normal to low normal blood levels of iron. This is the reason many newborn pigs and foals require supplemental iron.


Please reply – this subject is interesting. We have reduced the level of iron oxide in Life Data products due to consumer misunderstanding of our products. The iron oxide reduction in Life Data products does not have a nutritional impact on the horse. Also if you can provide me with the lot number of your Farrier’s Formula Double Strength, I would be happy to let you know whether you have the reduced iron oxide formula that we started producing in 2014.


Thanks for the inquiry! I am looking forward to hearing back from you.


Scott Gravlee, DVM, CNS

Equine Nutrition Consultant

Life Data Labs, Inc

Home - Life Data Labs USA


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