An international unit (IU) is an internationally accepted amount of a substance. This type of measure is used for the fat-soluble vitamins (such as vitamins A, D and E) and certain hormones, enzymes, and biologicals (such as vaccines). The definition of an international unit (IU) is generally arbitrary, technical, and eminently forgettable. For exa [..]

A unit used to measure the activity of many vitamins, hormones, enzymes, and drugs. An International Unit is the amount of a substance that has a certain biological effect. For each substance there is [..]

IU is a measurement unit that is primarily used on nutrition labeling for vitamin A. One IU is equivalent to 0.3 mcg of retinol, 0.6 mcg of beta-carotene, or 1.2 mcg other provitamin-A carotenoids.

An internationally accepted amount of a substance based on its biological activity or effect; used as a measurement for fat-soluble vitamins.

A standard unit of potency of a biological agent (e.g., vitamin, hormone, antibiotic, antitoxin); also called a USP unit in the U.S.

A unit used to measure the activity of many vitamins, hormones, enzymes, and drugs. An International Unit is the amount of a substance that has a certain biological effect. For each substance there is an international agreement on the biological effect that is expected for 1 International Unit. Also called IU.

a measurement of biological activity

A measure of potency based on an accepted international standard. It is usually used with beta-carotene and vitamins A, D, and E. Because it is a measure of potency, not weight or volume, the number of milligrams in an IU varies, depending on the substance being measured.