In a study(1) that was performed this year designed to study the effects of a high protein diet in young men, the blood markers for kidney function of 77 men who participated in an average of 6 hours of weight training per week (average age of 26), and ate a diet consisting of 19% protein were analyzed. Their protein intake came out to be about 0.76 grams of protein per pound bodyweight, which is very close to the 1 gram per pound minimum that is typically recommended for bodybuilders. Primary blood tests for kidney function were ran in which blood urea nitrogen, uric acid and creatinine levels were monitored. The measurements showed that all of these items were within normal parameters in all participating men.
Therefore, one can conclude that a high protein diet does not apply stress on healthy kidneys.
It must be mentioned that kidney function naturally declines with age due to the gradual loss of nephrons which are the kidney's filtering units. This loss can be caused by ailments like heart disease since in this case the blood flow to the kidneys is reduced. Also untreated high blood pressure can lead to kidney damage as well as long term use of prescription and non prescription pain relievers such as aspirin.
References
(1) LaBounty, P, et al. (2005). Blood markers of kidney function and dietary protein intake of resistance trained males. J Int Soc Sports Nutr.2:5
Creatine -
http://www.nlm.nih.gov/medlineplus/d...tural/873.html
check all the references there as well.
Do you have your PHD in Broscience?