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Relationships between vitamin A and vitamin E in the chick
Summary
High vitamin A intake significantly reduces plasma vitamin E (tocopherol) levels in animals. Vitamin E levels did not affect vitamin A (retinol) levels, and dietary oil had no impact on this interaction.
Area of Science:
- Animal Nutrition
- Nutritional Biochemistry
- Vitamin Metabolism
Background:
- Vitamins A and E are essential fat-soluble vitamins with crucial but distinct physiological roles.
- Interactions between vitamin A and vitamin E have been reported, but the precise mechanisms and effects of varying dietary levels require further elucidation.
- Understanding these interactions is vital for optimizing animal health and productivity through balanced nutrition.
Purpose of the Study:
- To investigate the impact of varying dietary levels of vitamin A and supplemental vitamin E on plasma vitamin concentrations in animals.
- To examine the influence of dietary oil on the interaction between vitamins A and E.
- To assess the effects of high oral vitamin A doses on the absorption, distribution, and elimination of vitamin E.
Main Methods:
- Animals were fed diets with two levels of vitamin A (10,000 or 50,000 IU/kg) and four levels of vitamin E (0-150 mg/kg), with or without added oil.
- Plasma levels of retinol and tocopherol were analyzed.
- The absorption, distribution, and elimination of radiolabeled vitamin E were studied following oral or intravenous administration alongside a high oral dose of vitamin A.
Main Results:
- Higher dietary vitamin A supplementation significantly decreased plasma tocopherol levels.
- Dietary vitamin E levels did not influence plasma retinol concentrations.
- Dietary oil did not alter the observed interaction between vitamins A and E.
- A high oral dose of vitamin A reduced radioactivity in tissues when both vitamins were given orally, but not when routes of administration bypassed gastrointestinal interaction.
Conclusions:
- High vitamin A intake negatively impacts vitamin E status by reducing plasma tocopherol levels.
- The interaction primarily affects vitamin E status rather than vitamin A status.
- Gastrointestinal absorption appears to be a key site for the antagonistic interaction between high oral doses of vitamin A and vitamin E.