Vitamin A: An Essential Nutrient
Vitamin A is a fat-soluble nutrient found in animal products as preformed vitamin A (retinol) and in fruit and vegetables as the provitamin A, beta-carotene.
It is necessary for healthy vision, the immune system, and reproduction, and also helps the heart, lungs, kidneys, and other organs work properly.
Vitamin A is required for regulating the growth and specialization of almost all cells in the human body.
It takes part in embryonic development, organ formation during fetal development, normal immune functions, and eye development and vision.
Symptoms of Vitamin A Deficiency
Deficiency of vitamin A is linked to various health issues, including:
Increased susceptibility to night blindness.
Infections, thyroid disorders, and skin disorders are also associated with vitamin A deficiency.
New RDA Regulations for Vitamin A
The FDA has introduced new labeling regulations for foods and dietary supplements containing vitamin A.
Vitamin A will be listed on product labels only in μg RAE (retinol activity equivalents) and not IUs.
The recommended dietary allowance (RDA) for vitamin A is 700 micrograms of retinol activity equivalents (μg RAE)/day for women and 900 μg RAE/day for men.
The upper intake level for vitamin A in adults is 3,000 μg RAE/day, but it only applies to non-carotenoid forms of vitamin A.
| Age | Male | Female | Pregnancy | Lactation |
|---|---|---|---|---|
| 0–6 months* | 400 mcg RAE | 400 mcg RAE | ||
| 7–12 months* | 500 mcg RAE | 500 mcg RAE | ||
| 1–3 years | 300 mcg RAE | 300 mcg RAE | ||
| 4–8 years | 400 mcg RAE | 400 mcg RAE | ||
| 9–13 years | 600 mcg RAE | 600 mcg RAE | ||
| 14–18 years | 900 mcg RAE | 700 mcg RAE | 750 mcg RAE | 1,200 mcg RAE |
| 19–50 years | 900 mcg RAE | 700 mcg RAE | 770 mcg RAE | 1,300 mcg RAE |
| 51+ years | 900 mcg RAE | 700 mcg RAE |
* Adequate Intake (AI), equivalent to the mean intake of vitamin A in healthy, breastfed infants.
Food Sources of Vitamin A
Animal-based food sources of vitamin A include dairy products, liver, and fish liver oils.
Rich sources of provitamin A carotenoids, which can be converted to vitamin A in the body, include orange and green vegetables like sweet potato and spinach.
Contraindications for Vitamin A Supplements
Pregnant women should not consume excessive amounts of preformed vitamin A in supplement form (such as retinol, animal-based vitamin).
While sufficient vitamin A intake is necessary for healthy fetal development, it is recommended to obtain it from plant-based sources like beta-carotene.
Prenatal multivitamins typically contain vitamin A derived from beta-carotene in low dosages.
The tolerable upper intake level for vitamin A in adults is set at 3,000 μg RAE/day (but it does not apply to vitamin A derived from carotenoids).
References-
National Institutes of Health. 2019. Vitamin A Fact Sheet for Health Professionals. [ONLINE] Available at https://ods.od.nih.gov/factsheets/VitaminA-HealthProfessional/.
Oregon State University. 2019. Vitamin A. [ONLINE] Available at https://lpi.oregonstate.edu/mic/vitamins/vitamin-A.
