Vitamin A is measured using Retinol Equivalents (RE). The contribution of both retinol and beta-carotene is used to determine the total vitamin A content of a specific food.

Vitamin A can be calculated from its content of retinol and beta-carotene and its derivatives, based on the following formula:

total vitamin A (RE) = µg of retinol + ( µg of beta-carotene ÷ 6)

International Units (IU) were formerly used to express the vitamin A content of a food. To convert IU of vitamin A into Retinol Equivalents, the following formulae are used:

IU retinol÷3.33 = RE
IU beta-carotene ÷ 10 = RE