Research into Vitamin E Supplementation to Combat Oxidative Stress in Equines

Research into Vitamin E Supplementation to Combat Oxidative Stress in Equines: A Mini-Review

J Equine Vet Sci. 2026 Nov 4:106198. doi: 10.1016/j.jevs.2026.106198. Online ahead of print.
Authors
Dylan S Matsuda 1 , Lucia Seale 2 , Caleb C Reichhardt 3
Affiliations

1 Department of Human Nutrition, Food, and Animal Sciences, University of Hawai’i at Mānoa, 1955 East-West Road, Honolulu, Hawai’i, 96822, United States.
2 Pacific Biosciences Research Center, University of Hawai’i at Mānoa, 1993 East-West Rd, Honolulu, HI 96822, United States.
3 Department of Human Nutrition, Food, and Animal Sciences, University of Hawai’i at Mānoa, 1955 East-West Road, Honolulu, Hawai’i, 96822, United States. Electronic address: ccreichh@hawaii.edu.

PMID: 42982149
DOI: 10.1016/j.jevs.2026.106198

Abstract

Oxidative stress is a concern in performance horses because intense and prolonged exercise increases production of reactive oxygen species (ROS) in contracting skeletal muscle. Low ROS concentrations support normal muscle function and adaptation, but excess ROS can damage lipids, proteins, and DNA. Vitamin E, particularly alpha tocopherol, is a lipid-soluble antioxidant that interrupts lipid peroxidation by donating a hydrogen atom to lipid peroxyl radicals. This mini-review summarizes recent equine research on vitamin E supplementation and exercise-induced oxidative stress. Results are variable and appear to depend on dose, form, baseline vitamin E status, and exercise intensity. Natural RRR-α-tocopherol raised serum alpha tocopherol more than synthetic vitamin E, and a water-dispersible liquid formulation rapidly increased serum concentrations in horses with subclinical deficiency, although studies of these formulations are small and limited to subclinical or healthy horses. The review also covers vitamin E metabolism, the role of alpha tocopherol transfer proteins in equine neurologic disease, forage sources of vitamin E, the interaction of vitamin E with selenium, and daily rhythms of oxidative parameters. Further controlled studies with larger sample sizes are needed to define the optimal dose, form, and timing of vitamin E supplementation in performance horses.

Keywords: Alpha Tocopherol; Antioxidant; Exercise; Horses; Oxidative Stress; Training.

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