Vitamin E Supplementation in Cats’ Diets

This study investigated the effects of vitamin E (Vit E) and selenium (Se) dietary supplementation on feline immunological parameters. Vit E and Se are known to have immune-enhancing effects when supplemented in human and animal diets. Though the mechanism is not completely understood, Vit E is thought to enhance innate and acquired immunity through its antioxidant activity, reduction of immunosuppressive compounds (eg, prostaglandin E₂ and nuclear factor κB), and enhancement of interleukin-2 production. Little is known about the effects of Vit E and Se supplementation on feline immune function.  

Cats (n = 72) of varying ages were assigned to receive 1 of 9 diets supplemented with varying Vit E and Se levels or a control diet. Blood samples were drawn on days 0, 14, and 28, and leukocytes were analyzed for lymphocyte proliferation, immunophenotype, and phagocytic activity. After 28 days, enhanced lymphocyte proliferative responses were observed in cats fed diets containing Vit E. A higher dose of Vit E did not have a greater effect than a moderate dose. Vit E had a strong positive effect on peripheral blood leukocyte phagocytic activity. Se supplementation did not affect immune function. Immunophenotype was not altered by Vit E or Se supplementation. The authors conclude that Vit E supplementation at moderate levels is adequate to induce beneficial effects on feline immune function.

Commentary

Vit E is recommended as adjunct treatment of a variety of chronic inflammatory or immune-mediated diseases—particularly of the skin and gastrointestinal tract—in dogs and cats. Most of these recommendations are extrapolated from other species so, for feline patients, this article is particularly valuable. Although it is tantalizing to promote Vit E supplementation based on the significant finding of enhanced lymphocyte function, specific benefits are not clear. The long-term effects and specific dosing recommendations in healthy cats are needed before it can be evaluated for disease therapy. Future studies should clarify Vit E’s immunologic impact and guide study of supplementation for specific disease conditions.—Elizabeth Layne, DVM, Resident in Dermatology (University of Wisconsin)