12. How can I convert 'mg' or 'mcg' to 'IU' for Vitamins A, D and E?
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
所以，Costco 的维生素D3现在标为 50mcg，其实和以前的2000 IU 完全一样。
