This has definitely been an ongoing discussion with much research surrounding it. From what I've seen, higher protein intakes (such that would be seen in athletes consuming above the RDA in protein) are not associated with decrease in bone health or risk for fractures and osteoporosis. It could even be speculated that those who generally consume more protein exercise more, and perform the necessary weight bearing work to increase bone mineral density. The same goes for kidney function in healthy adults. High protein diets do not seem to decrease or harm kidney function. It is only in those who have declining kidney function (who are at CKD stage 3) do we lower the protein to reduce the rate of degenerative function. No something the average healthy person has to worry much about.