Is it possible to convert international units seen on such items as vitamin bottles to milligrams or micrograms?
Development Ofweights and Measures
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No, there is no direct way to convert international units (IU) to mass units, such as milligrams. Most familiar to people who read vitamin and mineral bottles, an IU has nothing to do with weight; it is merely the measure of a drug or vitamin’s potency or effect. Although it is possible to convert some items’ IUs to a weight measurement, there is no consistent number. This is because not all materials weigh the same and the preparation of substances vary, making the total weight of one preparation differ from another.
But there are some substances that can be converted, because for each substance, there is an international agreement specifying the biological effect expected with a dose of 1 IU. For example, for vitamins, 1 IU of vitamin E equals 0.667 milligram (mg); 1 IU of Vitamin C is equal to 0.05 mg. In terms of drugs, 1 IU of standard preparation insulin represents 45.5 micrograms; 1 IU of standard preparation penicillin equals 0.6 microgram.