Question: what are iu in vitamins?
Answer: An IU (International Unit) is a unit of measurement for vitamins and other specific biologically active substances. ... Vitamin A: 1 IU is the biological equivalent of 0.3 mcg retinol, or of 0.6 mcg beta-carotene. Vitamin D: 1 IU is the biological equivalent of 0.025 mcg cholecalciferol or ergocalciferol.