Relationships between vitamin A and vitamin E in the chick.

Plasma levels of vitamins A and E were analysed during the dietary administration of two levels of vitamin A (10 000 or 50 000 IU/kg) in combination with four levels of supplemental vitamin E (0, 50, 100, or 150 mg/kg) and with or without a supplement of oil to the diet. Tocopherol levels in plasma were markedly decreased by the higher vitamin A supplementation. In contrast, the various vitamin E intakes had no influence on plasma retinol levels. The addition of oil to the diet did not affect this interaction. The absorption, distribution and elimination of labeled 3H-dl-alpha-tocopheryl acetate after an oral or intravenous administration, in combination with a high oral dose of vitamin A (100 000 IU/chick), were studied. The high oral single dose of vitamin A reduced the levels of radioactivity in all the analysed tissues and organs, when both vitamins were administered orally. However, vitamin A did not affect distribution and elimination of radioactivity, when an interaction in the gastro-intestinal tract was avoided by different routes of administration.