07/06/2025
The 2025 Equine Science Society conference was a blast! We covered several topics, but one of the hottest discussions was about vitamin E, the antioxidant crucial for horse muscle health, nervous system, and cellular defense. A Purina study found that horses in training and maintenance had sufficient serum vitamin E levels regardless of their fitness. Vitamin E also gradually accumulates in adipose (fat) tissue.
Vitamin E deficiency remains a common issue. Pasture may not be accessible year-round, and stored hay can lose up to 50% of vitamin E every month. Some horses may not show clear signs of deficiency but still suffer at the mitochondrial level. Dr. Finno from UC Davis documented a case of muscle trembling and an inability to back up, which required increasing vitamin E to 8 μg/mL for clinical signs to disappear—four times the adequate threshold of 2 μg/mL (under 1.5 is considered deficient). Vitamin E deficiency is associated with several diseases in different ages, such as equine degenerative myeloencephalopathy (EDM) in foals. Boosting vitamin E in late pregnancy is crucial for foals since it is present in colostrum. Supplementing foals around 3–4 months old is also a good strategy.
Vitamin E supplements come in different forms. The natural form, D-alpha-tocopheryl (RRR), can increase serum vitamin E levels in 24 hours, while the synthetic version, DL-alpha-tocopheryl acetate, usually takes 8–10 weeks to show results. Polyphenol-added antioxidant supplements can enhance vitamin E retention. A University of Montreal study found that older horses retained vitamin E better and faster when supplemented with polyphenols, reaching optimal levels in just 31 days compared to 52 days in younger horses.
factors such as age, health status, source, and others
Regarding vitamin E's interaction with other common illnesses, we might guess that equine gastric ulcer syndrome (EGUS) drains vitamin E reserves, but a Purina study indicated otherwise. Even during gastric ulcer protocols, horses maintained serum vitamin E above 2 μg/mL. Gastric ulceration did not appear to mobilize vitamin E from adipose tissue or reduce circulating vitamin E.
To conclude, vitamin E is a dynamic nutrient whose effects depend on factors such as age, health status, source, and others. Performing routine vitamin E diagnostics is crucial for horse health.
References:
- Beaumont, M., Lessard, M., Desrochers, A., Beaudry, F., & Myrie, S. B. (2022). Age may impact vitamin E status in horses consuming a polyphenol-based supplement. University of Montreal.
- Finno, C. J. (2025). How Nutrigenomics Impacts Equine Health – A Case Study of Vitamin E. University of California, Davis.
- Purina Animal Nutrition. (2025). Effect of gastric ulceration on vitamin E status in horses. Purina Equine Research.
- Purina Animal Nutrition. (2025). Physiology of vitamin E in maintenance and exercising horses as measured via blood and adipose tissue concentrations. Purina Equine Research.
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