Dietary (n-3) Fatty Acid and Vitamin E Interactions in Rats: Effects on Vitamin E Status, Immune Cell Prostaglandin E Production and Primary Antibody Response

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Abstract
To examine the interaction between dietary fat and vitamin E at the level of the rat immune system, a 2 × 3 factorial study was designed. Weanling female Sprague Dawley rats were fed for 8–9 wk diets that contained either corn oil (CO diet) or fish oil (FO diet) and one of three levels (30, 300, 900 mg/kg) of all-rac-α-tocopheryl acetate. At the lowest level of dietary vitamin E, α-tocopherol content of splenocytes from FO-fed rats was ∼40% lower (P < 0.05) than in those from CO-fed rats. Supplementation with all-rac-α-tocopheryl acetate elevated α-tocopherol in splenocytes from FO-fed rats but not in those from CO-fed rats, and reduced the relative proportion of arachidonic acid and eicosapentaenoic acid in the serum of CO-fed and FO-fed rats, respectively. Prostaglandin E production by isolated immune cells was not affected by all-rac-α-tocopheryl acetate supplementation. However, feeding the FO diet consistently reduced prostaglandin E synthesis by 70–80% as compared with the CO diet. Antibody production against sheep RBC was highest in rats fed the FO diet supplemented with 900 mg all-rac-α-tocopheryl acetate/kg of diet. However, antibody response was not directly correlated to diet-induced changes in immune cell prostaglandin E production or α-tocopherol content. Our data suggest that there are significant interactions between vitamin E and (n-3) fatty acids that affect the immune system and that further research in this area is warranted.