Protein must be processed under low-temperature and low-acid conditions to maintain the integrity and high quality. The amount of lactose in protein decreases as the protein level increases. Whey protein isolate is the purest form of whey and contains between 90 to 95 percent protein and little to no fat or lactose.

Inexpensive whey may be low in protein and high in lactose. Cheaper forms may be cheaply processed at high temperatures, reducing the nutritional value. You may find consuming whey protein and pure whey protein isolate may help with lactose intolerance.