Absorption of Different Oral Formulations of Natural Vitamin E in Horses Nicole M. Fiorellino, Emily D. Lamprecht, and Carey A. Williams, PhD ABSTRACT The objective of this study was to determine the effect of vitamin E source on plasma vitamin E concentration. Five different formulations of natural source vitamin E (4,000 IU/day) were supplemented to Standardbred mares (n ¼ 4 per group) for 14 days. Treatment 1 was given 10 g of 400 IU/g natural acetate (RRR-a-toco- pheryl-acetate) powder, treatment 2 was given 6.66 g of 600 IU/g natural acetate powder, treatment 3 was given 6.66 g of 600 IU/g natural alcohol (RRR-a-to- copherol) powder, treatment 4 was given 20 g of 200 IU/g micellized natural alcohol powder, and treatment 5 was given 8 mL of 500 IU/mL micellized natural alco- hol liquid. Blood samples were collected before supple- mentation (day 0), after day 7 and day 14 of supplementation, and analyzed for plasma a-tocopherol. Treatments 1, 2, and 3 increased (P < .05) from days 0 to 7, but remained similar at day 14. Treatments 4 and 5 also increased (P ¼ .004, and P < .0001, respectively) from days 0 to 7 and were higher (P < .05) than treat- ment 1, 2, and 3. Plasma levels peaked at day 7 and either plateaued or decreased (treatment 5, P ¼ .004) at day 14. The micellized alcohol formulations remained elevated (treatment 4) or decreased (treatment 5) after achieving peak blood concentration and, as hypothesized, tended to have plasma concentrations higher than the other vi- tamin E forms. Care should be taken to ensure that the most active biologically available form of vitamin E is provided in the diet to maximize its efficiency. Keywords: a-tocopherol; Antioxidant; Equine; Natural; Vitamin E INTRODUCTION A healthy diet for any animal must contain the correct bal- ance of different nutrients. The components of any diet must be balanced to include sufficient energy from carbo- hydrates and fats; however, an adequate diet should also contain ingredients/nutrients to provide water, protein, minerals, and vitamins. Vitamin E is one such nutrient, a fat-soluble vitamin that is present in nature as RRR-a-to- copherol. 1 The natural isomer a-tocopherol is unstable; thus, to improve stability for inclusion into complete feeds and supplements, the natural vitamin E is esterified, typi- cally with an acetate moiety. Natural vitamin E differs from synthetic vitamin E in that synthetic vitamin E (all- rac-a-tocopherol) contains a mixture of eight different di- astereoisomers, 1 of which only one of the isomers is iden- tical to natural vitamin E. Both synthetic and natural forms of vitamin E can be con- tained in various equine supplements and complete feeds. Ingold and colleagues 2 compared the absorption of natural a-tocopherol with that of synthetic a-tocopherol acetate in different rat tissues and found that most tissues had an affin- ity for the natural form over the synthetic acetate form. A study performed using human infants demonstrated a pref- erence for the natural tocopherol versus the synthetic form and a higher trans-placental transport efficiency of the nat- ural form to the developing fetus. 3 In other human studies, a preference for natural a-tocopherol over g-tocopherol has been shown. 4 Horses fed water-soluble natural vitamin E (RRR-a-tocopherol) had higher plasma vitamin E levels than horses fed either synthetic vitamin E (all-rac-a-toco- pheryl acetate) or natural vitamin E acetate (RRR-a-toco- pheryl acetate) at levels of 500 IU to 8000 IU per horse per day (Kane, personal communication). In addition to supplementing different vitamin E diaste- reoisomers, different physical forms of the supplement, either dry or liquid, or emulsified and micellized, are avail- able. Ochoa and colleagues 5 experimented with various forms of vitamin E supplemented to sheep, one of those being the micellized form. Micelles are similar to viruses or lipoproteins in their method of transport. They have a core-shell structure, which carries the deliverable mole- cule in its core surrounded by a shell for protection. Micelle stability increases with additional lipid moieties because of the presence of additional fatty acid acyls that increase the hydrophobic interaction within its core. 6 Controlled in vivo research must be conducted to iden- tify and quantify additional benefits of vitamin E SHORT COMMUNICATION From the Department of Animal Science, Equine Science Center, Rutgers, the State University, New Brunswick, NJ. Reprint requests: Carey A. Williams, PhD, 84 Lipman Dr, Bartlett Hall, New Brunswick, NJ 08901. E-mail: cwilliams@aesop.rutgers.edu 0737-0806/$ - see front matter Ó 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.jevs.2008.12.007 100 Journal of Equine Veterinary Science  Vol 29, No 2 (2009)