In relation to vitamins, what does IU stand for, literally…….?

….and how do you work out a dosage stated in IU's equivalent to the dosage in mcg (micrograms)?

There's a suggested dosage for a vitamin supplement in a book which says how much you should take in IU's, but I'm trying to work out if I would be taking too high a dose since it's also present in another supplement I would be taking, but the dosage is said in mcg on this other one.

Can anyone help?

Thanks : )

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Answer:
It stands for International Unit. The precise definition of one IU differs from substance to substance and is established by international agreement for each substance. There’s no equivalence among different substances; for instance, one IU of vitamin E does not contain the same number of milligrams as one IU of vitamin A.

For more, see this: http://en.wikipedia.org/wiki/Internation…

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Answer:
IU is “international units”, an effort on the part of the world health organization to bring some consistency and continuity to the world of supplements.

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Answer:
IU stands for international unit.

The dosages of different vitamins can be found here:

http://en.wikipedia.org/wiki/Internation…

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Answer:
It means μ, one millionth. So 1μg is one microgram.