(International Rat Unit) A unit of quantity of vitamin E, determined by the following biological assay. When a group of pregnant rats do not get enough vitamin E, they do not give birth; the fetuses are absorbed. One International Rat Unit is the minimum amount of dl-alpha-tocopherol acetate that must be given orally to tocopheral-deficient rats to prevent absorption of the fetuses in 50% of the rats.
Siebet et al in
Rauen, H. M. (editor)
Biochemisches Taschenbuch, 2nd ed, part 2.
Berlin: Springer Verlag, 1964.
A unit of mass for riboflavin, = 4 micrograms of riboflavin.
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