Two experiments were conducted to determine the effect of vitamin A supplementation on serum vitamin E in adult female northern fur seals (Callorbinus ursinus). In the first experiment five animals received, in addition to their routine dietary multivitamin supplement, a high-level vitamin A supplement (53 mu mol retinyl palmitate/d) for 30 d. Five seals consuming their routine dietary supplement served as controls. Serum vitamin E decreased significantly in animals receiving high-level vitamin A supplements. At the end of 30 d serum vitamin E averaged 18.6 mu g/mL in the control animals and 13.4 mu g/mL in the animals receiving the high-level vitamin A supplement. In experiment 2 ten animals received the high level vitamin A supplement for 60 d. After 30 d, serum vitamin E levels were reduced, but by 60 d had returned to baseline levels. However, the ratio of serum vitamin E to phospholipid, another index of vitamin E status, remained decreased. Although the exact mechanism of interaction is unknown, this study shows that when providing vitamin supplements for captive pinnipeds, vitamin interactions must be considered. The vitamin A supplementation currently used by some institutions seems unnecessary and may have detrimental effects on vitamin E status.
