Vitamin E /Selenium Supplementation in Horses
I live in Eastern Canada, a place known for low Vitamin E and Selenium levels. Blood work on one of my horses revealed deficiencies in both. When I analyzed the products that I could get to supplement him with, I noticed most contained forms of Vitamin E and Selenium that had very low bioavailabilty. The natural form of Vitamin E ( liquid greater than powder or pellet forms) and organic Selenium (vs inorganic) are the desired form to look for in a supplement.
With a better supplement, comes increased cost, but keep in mind the better product delivers more as it is more available to your horse.
I live in Canada. Currently the only liquid natural Vitamin E I can find is made by Kentucky Equine Research (Nano E). A close second? Mad Barn’s Natural Vitamin E and Vitamin E/ Selenium products.
ACVIM 2015
Carrie J. Finno, DVM, PhD, DACVIM; Stephanie J. Valberg, DVM, PhD, DACVIM
University of California-Davis, Davis, CA, USA; 2University of Minnesota, St. Paul, MN, USA
Vitamin E is an essential fat-soluble vitamin that is required for healthy neuromuscular function. VitE is actually a general term used to describe a family of eight naturally occurring closely related compounds. The family consists of two subgroups: tocopherols (saturated) and tocotrienols (unsaturated). Within each subgroup, there are four individual isoforms (α, β, γ, and δ) . Alpha-tocopherol (α-TP), specifically the natural RRR stereoisomer (RRR-α-TP), is the most bioavailable and bioactive form in animal tissues due to preferential uptake by the liver. The major dietary source of vitE in horses is forage, optimally providing approximately 2,000 IU/day of natural α-TP to grazing horses. However, the amount of fresh pasture available to horses is markedly decreasing, especially with recent drought conditions, and the amount of α-TP in hay declines markedly with processing and storage. Commercial feeds usually provide α-TP in the form of synthetic vitamin E, a less bioavailable formulation than natural α-TP containing a mixture of eight isomers (dl-α-tocopherol [all-rac-α-tocopherol]), of which only one is identical to the natural isomer. Thus, many horses receive far less α-TP than the dietary requirements of 1–2 IU/kg body weight, set by the 2007 National Research Council.
A deficiency of whole body vitE is typically assessed by measuring serum concentrations of one component of vitE, α-TP, with normal equine serum concentrations > 2 µg/mL. Whether or not a deficiency of vitE has an impact on health depends upon individual genetic factors, the temporal occurrence of deficiency during development, and the duration of deficiency. Older horses that have been vitE deficient for ≥ 18 months can develop equine motor neuron disease (EMND) resulting in clinical signs of weakness and neurogenic muscle atrophy. Some adult horses, potentially those with shorter duration vitE deficiency, have a vitE-deficient myopathy(VEM) and present with muscle weakness, low muscle α-TP concentrations, mitochondrial alterations in skeletal muscle but no evidence of neurogenic atrophy
The type and formulation of vitE supplements has a major impact on their bioavailability. Natural vitE, RRR-α-TP, is more bioavailable than synthetic vitE and therefore many equine supplements now strongly market the "natural" (i.e., RRR) form. The natural formulation is available as an esterified form (α-TP acetate) to prolong shelf life (i.e., powder or pellet) or water dispersible (i.e., liquid) formulation with higher biopotency.
Alpha-TP acetate may have less bioavailability because the ester has to be removed and the α-TP made water-dispersible by the action of bile salts (micellization). In contrast to the α-TP acetate, the liquid formulation leads to a more rapid increase (within 24 hours) in serum α-TP concentrations in horses. Both formulations are useful for equine practice and selection of the appropriate formulation will depend upon whether or not vitE supplements are being used to prevent deficiency, to treat a deficiency, or to treat a disease associated with vitE deficiency.
