International Unit - Mass Equivalents of 1 IU

Mass Equivalents of 1 IU

For some substances, the precise mass equivalent of one IU is later established. If that happens, the former IU mass for that substance is officially abandoned in favor of a newly established mass. The unit count often will still remain in use.

• Vitamin A: 1 IU is the biological equivalent of 0.3 μg retinol, or of 0.6 μg beta-carotene
• Vitamin C: 1 IU is 50 μg L-ascorbic acid
• Vitamin D: 1 IU is the biological equivalent of 0.025 μg cholecalciferol/ergocalciferol
• Vitamin E: 1 IU is the biological equivalent of about 0.667 mg d-alpha-tocopherol (2/3 mg exactly), or of 0.45 mg of dl-alpha-tocopherol acetate.
• Insulin: 1 IU is equivalent to 0.0347 mg of human insulin (28.8 IU/mg).