The intake recommendations for vitamin A are based on the amount needed to ensure adequate stores (four months) of retinol in the body to support normal reproductive function, immune function, gene expression, and vision.
In 1993, the European Scientific Committee for Food set population reference intakes (PRI) for vitamin A in micrograms (mcg) of preformed vitamin A (Retinol Activity Equivalents, RAE, see below) and international units (IU) per day (22):
| Age | Males: mcg/day (IU/day) | Females: mcg/day (IU/day) |
| 6–12 months | 350 (1,166 IU) | 350 (1,167 IU) |
| 1–3 years | 400 (1,333 IU) | 400 (1,333 IU) |
| 4–6 years | 400 (1,333 IU) | 400 (1,333 IU) |
| 7–10 years | 500 (1,667 IU) | 500 (1,667 IU) |
| 11–14 years | 600 (2,000 IU) | 600 (2,000 IU) |
| 15–17 years | 700 (2,333 IU) | 600 (2,000 IU) |
| 18 years and older | 700 (2,333 IU) | 600 (2,000 IU) |
| Pregnant | - | 700 (2,333 IU) |
| Breast feeding | - | 950 (3,167 IU) |
Many European nutrition societies such as the German Nutrition Society (DGE) recommend a daily intake of 0.8 mg vitamin A (retinol) for women and 1 mg for men (23). As vitamin A plays an important role for the healthy development of the embryo and the newborn, pregnant women should take 1.1 mg vitamin A per day from the 4th month on. For breastfeeding women the recommended daily intake is 1.5 mg.
In 2001, the U.S. Food and Nutrition Board (FNB) established recommended dietary allowance (RDA) values for vitamin A in both micrograms (mcg) of preformed vitamin A (Retinol Activity Equivalents, RAE, see below) and international units (IU) (24):
| Life Stage | Age | Males: mcg/day (IU/day) | Females: mcg/day (IU/day) |
| Infants (AI) | 0–6 months | 400 (1,333 IU) | 400 (1,333 IU) |
| Infants (AI) | 7–12 months | 500 (1,667 IU) | 500 (1,667 IU) |
| Children | 1–3 years | 300 (1,000 IU) | 300 (1,000 IU) |
| Children | 4–8 years | 400 (1,333 IU) | 400 (1,333 IU) |
| Children | 9–13 years | 600 (2,000 IU) | 600 (2,000 IU) |
| Adolescents | 14–18 years | 900 (3,000 IU) | 700 (2,333 IU) |
| Adults | 19 years and older | 900 (3,000 IU) | 700 (2,333 IU) |
| Pregnancy | 18 years and younger | - | 750 (2,500 IU) |
| Pregnancy | 19 years and older | - | 770 (2,567 IU) |
| Breast-feeding | 18 years and younger | - | 1,200 (4,000 IU) |
| Breast-feeding | 19 years and older | - | 1,300 (4,333 IU) |
A consumption of excess preformed vitamin A (retinol) during pregnancy is known to cause birth defects (see Safety).
For a detailed overview of recommended daily intakes (PRIs/RDAs) of vitamins and minerals for adults derived from different countries and organizations see PDF.
Provitamin A intake – Retinol Activity Equivalents
Different sources of vitamin A such as food, supplements, and provitamin A carotenoids have different potencies. Beta-carotene is less easily absorbed than retinol and must be converted to retinal and retinol by the body; other provitamin A carotenoids in foods (e.g., alpha-carotene) are even less easily absorbed than beta-carotene.
The international standard of measure for vitamin A is ‘retinol activity equivalents’ (RAE), which considers the conversion ratio and represents vitamin A activity as retinol. According to the U.S. Food and Nutrition Board, the conversion factors are the following (24):
| Quantity consumed | Quantity converted to retinol | RAE ratio |
| 1 mcg dietary or supplemental vitamin A | 1 mcg of retinol* | 1:1 |
| 12 mcg dietary beta-carotene | 1 mcg of retinol | 12:1 |
| 24 mcg dietary alpha-carotene | 1 mcg of retinol | 24:1 |
* An older international standard, still commonly used, is the international unit (IU): One IU is equivalent to 0.3 microgram (mcg) retinol, and one mcg of retinol is equivalent to 3.33 IU retinol.
The conversion factors for dietary beta-carotene to vitamin A have changed over time and have not always been the same in different studies and surveys. Many researchers suggest a conversion factor of 1:6 ─ to produce 1 mcg retinol from fruits and vegetables, 6 mcg of dietary beta-carotene may be needed.