You will be finding the certain formulation is highlighting ingredients in IU. For example in case of Vitamin D preparation vitamin D3 unit will be IU. Refer below –
An IU (International Unit) is a unit of measurement for vitamins and other specific biologically active substances.
The precise measure of one IU differs from substance to substance and is established by international agreement for each substance.
For example, vitamin E exists in a number of different forms having different biological activities. Rather than specifying the precise type and mass of vitamin E in a preparation, the Supplement Facts label summarizes the biological activity of the forms present as the number of International Units of vitamin E.
The equivalents of 1 IU for selected vitamins are:
- 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
- Vitamin E: 1 IU is the biological equivalent of 0.67 mg d-alpha-tocopherol, or 0.9 mg of dl-alpha-tocopherol
IU to mcg conversion guideline
To convert Vitamin A as retinol:
From IU to mcg: IU/3.33 = mcg
For example: 5000 IU/3.33 = 1500 mcg
From mcg to IU: mcg * 3.33 = IU
To convert Vitamin A as beta-carotene:
From IU to mcg: IU/1.66 = mcg
From mcg to IU: mcg * 1.66 = IU
To convert Vitamin D:
From IU to mcg: IU/40 = mcg
For example: 400 IU/40 = 10 mcg
From mcg to IU: mcg * 40 =IU
To convert Vitamin E if the product label has dl-Alpha-tocopherol as the ingredient:
From IU to mg: IU * 0.9 = mg
For example: 30 IU * 0.9 = 27 mg
From mg to IU: mg * 1.1 = IU
To convert Vitamin E if the product label has d-Alpha-tocopherol as the ingredient:
From IU to mg: IU * 0.67 = mg.
For example: 30 IU * 0.67 = 20.1 mg
From mg to IU: mg * 1.5 = IU
Note: Conversion mag to mcg
In the metric system, 1000 milligrams (mg) is a unit of mass equal to 1 gram and 1000 micrograms (mcg) is equal to 1 milligram (mg).