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Safety of vitamin A
1Department of Clinical Nutrition, Hoffmann-La Roche Inc, Nutley, NJ 07110-1199.
The American Journal of Clinical Nutrition
|February 1, 1989
Summary
Vitamin A is essential, but both deficiency and excess can cause harm. Deficiency leads to blindness and increased child mortality, while toxicity from supplements can cause acute and chronic health issues.
Area of Science:
- Nutrition Science
- Public Health
- Toxicology
Background:
- Vitamin A adequacy is crucial for health, with established recommended dietary allowances (RDAs).
- Vitamin A deficiency can lead to severe health consequences, including xerophthalmia, permanent blindness, and increased childhood mortality.
- Overconsumption of vitamin A supplements can result in toxicity, known as hypervitaminosis A.
Purpose of the Study:
- To discuss vitamin A adequacy in relation to recommended allowances.
- To outline the health risks associated with both vitamin A deficiency and toxicity.
- To explore factors influencing chronic vitamin A toxicity and its teratogenic potential.
Main Methods:
- Review of recommended dietary allowances for vitamin A.
- Analysis of reported cases and symptoms of vitamin A deficiency and toxicity.
- Examination of factors contributing to chronic hypervitaminosis A and teratogenic effects.
Main Results:
- Vitamin A deficiency causes blindness and increases child mortality.
- Acute vitamin A toxicity can occur from ingesting over 500,000 IU, with reversible symptoms.
- Chronic toxicity is influenced by dosing, form, health status, diet, and vitamin interactions; teratogenic effects observed in animals and suspected in humans.
Conclusions:
- Maintaining adequate vitamin A levels is critical, balancing the risks of deficiency and toxicity.
- While vitamin A toxicity is rare, awareness of risks associated with high-dose supplements is important.
- Further research is needed to establish definitive cause-and-effect relationships for teratogenic effects in humans.