Please post the conversion factor between an international unit of a vitamin and its metric equivalent. i.e. how many IU = X milligrams or micrograms?
An international unit of a vitamin varies. I use the following table from “Food Chemistry and Nutritional Biochemistry by Zapsalis and Beck.
Vitamin A, 1 IU retinol = 0.300 – 0.344 micrograms
Vitamin A, 1 IU beta carotene = 0.600 micrograms
Vitamin E, 1 IU tocopherol = 1.5 milligram
For beta-carotene, I have calculated the following conversion for 25,000 IU of beta-carotene = 15,000 micrograms.