Recommended Dietary Allowance (RDA) for Vitamin A
The RDA for vitamin A is 900 μg retinol activity equivalents (RAE) per day for adult men and 700 μg RAE per day for adult women, with an upper tolerable limit of 3,000 μg/day to avoid toxicity. 1
Standard RDA Values by Population
Adults
- Men: 900 μg RAE/day (approximately 3,000 IU) 1, 2
- Women: 700 μg RAE/day (approximately 2,333 IU) 1, 2
- Upper limit: 3,000 μg/day for all adults to prevent adverse health effects 1
Pediatric Populations
- Ages 2-5 years: Mean intake data shows approximately 606 μg/day in healthy children 3
- Ages 6-11 years: Mean intake approximately 618 μg/day 3
- Ages 12-19 years: Mean intake approximately 611 μg/day 3
- Infants 7-36 months: 250 μg RE/day 4
- Adolescents 15-17 years: 750 μg RE/day 4
Special Populations
- Pregnant women: 770 μg RAE/day, but should not exceed 3,000 μg/day total intake due to teratogenic risk 5, 6
- Lactating women: 1,300 μg RAE/day to support milk production 5
Understanding Vitamin A Measurement Units
The conversion between different vitamin A units is critical for accurate dosing 4:
- 1 μg RAE = 1 μg retinol = 12 μg beta-carotene = 3.33 IU vitamin A 4
- Provitamin A carotenoids (like beta-carotene) never cause hypervitaminosis A, unlike preformed retinol 4
Clinical Assessment of Vitamin A Status
Biochemical Markers
- Deficiency: Blood retinol concentration <0.70 μmol/L (200 μg/L) indicates insufficient intake 4
- Adequate status: Blood retinol >1.05 μmol/L (300 μg/L) 4
- Optimal body stores: 20 μg vitamin A/g liver (0.07 μmol/g) represents adequate reserves for 4 months 2
Important caveat: Plasma retinol concentrations do not reliably reflect vitamin A status except in cases of deficiency or excess, due to tight homeostatic control 5
Safety Considerations and Toxicity Thresholds
Acute Toxicity
- Acute hypervitaminosis A occurs after single doses ≥500,000 IU (>100 times the RDA) in adults 6
- Symptoms are usually reversible upon cessation 6
Chronic Toxicity Risk
- Intakes up to 3 times the RDA (approximately 3,000 μg RE) are generally well-tolerated 5
- The Institute of Medicine established 3,000 μg/day as the upper limit to avoid adverse health effects 1
Pregnancy-Specific Warnings
- Critical: Women of childbearing age should not exceed 3,000 μg RE/day total intake due to potential teratogenic effects 5, 6
- Both excess and deficiency of vitamin A during pregnancy have been associated with congenital malformations 6
- The American Pediatric Society recommends pregnant women limit total daily intake to 3,000 μg RE 5
Practical Clinical Considerations
Populations at Risk for Deficiency
- Low-income groups and individuals following weight-reducing or unbalanced diets 5
- Children with chronic conditions like sickle cell disease may require higher doses than standard RDA 7
- Developing countries where vitamin A deficiency causes xerophthalmia and blindness 5
Dietary Sources vs. Supplementation
- RDA values can be achieved through diet alone using either preformed vitamin A (animal sources) or provitamin A carotenoids (fruits and vegetables) 5
- Non-breastfed infants may exceed recommended intake or even upper limits (600 μg/day) with some formulas 4