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According to Merriam-Webster Dictionary

Whey is the watery part of milk that is seperated from the coagulable part or
curd.  esp.  in the process of making cheese and that is rich in lactose,
minerals & vitiams.  also contains lactalbumin and traes of fat.

If you seem to have a reaction when eating a product with whey it maybe that
you are lactose intolerant.  Jane