For those who are lactose intolerant, there is whey isolate which pretty much all protein supplement companies offer as an alternative. It's more expensive than regular whey, of course.

I do NOT agree with the above. My peers at bodybuilding.com, however, would unanimously agree that protein causes no long-term damage while my friends who are practicing doctors do warn of kidney damage. The argument goes both ways: protein is broken down into urea and nitrogen and then benignly excreted...versus...high amounts of protein intake causes kidney stones. Also, the increased filtration needed to remove urea & nitrogen causes elevated kidney function and stresses the organ. I've come across enough studies that hint at the possibility of kidney damage BUT there are no definitive conclusions. For every study you find saying there is damage, there's another study proving otherwise.

If you decide to supplement with whey, be sure to hydrate properly. I also agree with speaking to your doctor about possible problems, such as testing for kidney function (BUN and creatinine) and discussing any family history of diabetes/high BP. Be careful if you decide to have more than 1.5g/kg (bodyweight)/day of protein. Also, insist on regular kidney function tests once you're on the supplement. I know of bodybuilders who pay out of pocket to have their blood tested for BUN and creatinine levels. Of course, they are on a "stack" of supplements including but not limited to pro-hormones/creatine/b-alanine/etc.

If you are concerned, why not just drink an extra glass of milk or eat a bit more meat? The typical American diet usually contains quite a bit of protein though.