Vitamin Units like IU and RE — What Do They Stand for?
International Units, or IUs, is an older system of measurement used with the fat-soluble vitamins A, D, E and K. The IU system is based on a standard unit of biological activity, or potency. The International Unit system was used when U.S. Recommended Daily Allowances (USRDA) first began to appear on food labels in 1968. On the food label, the USRDAs have now been replaced by the Daily Value (DV). The use of International Unit, however, has remained. Scientists have identified the precise chemicals responsible for all of the known vitamins. In an attempt to gain precision, vitamins have shifted over to measuring amounts of those key substances. For example, the key substance that provides the body with its vitamin A activity is named retinol (RHET-in-awl). The measure for vitamin A is now in the process of being changed from International Units of vitamin A to a new unit called “retinol equivalents” or RE Your confusion stems from the fact that, at the present time, we are right in the
