High-protein diets are not hazardous for the healthy kidneys.

High-protein diets are not hazardous for the healthy kidneys Sir, The recent letter by Luyckx and Mardigan [1] has a somewhat misleading title, as there is certainly no scientific evidence that the high-protein diets are hazardous for healthy kidneys. Furthermore, real world examples support this contention since protein-related kidney problems are essentially non-existent in the body-building community in which extremely high-protein intake has been the norm for over half a century [2]. Also, men in the famous Lewis and Clark expedition across America reportedly ate as much as nine pounds of buffalo meat each day with no ill effects [3]. That is well over 600 g of protein as a daily minimum. Nevertheless, Anderson and Brenner suggested that high-protein intake played a central role in the decline of renal function with age and that protein restriction might prevent this decline [4]. However, as discussed by Walser [5], this recommendation cannot be supported for a number of reasons: (i) caloric restriction is more effective in rats than is protein restriction in retarding age-associated decline in renal function; (ii) protein restriction tends to lower glomer-ular filtration rate rather than increase it; and (iii) there is certainly no evidence suggesting that a high intake of protein causes progressive reduction in renal function. Thus, Walser concluded that it is clear that protein restriction does not prevent decline in renal function with age, and, in fact, is the major cause of that decline [5]. According to Walser [5], a better way to prevent the decline would be to increase protein intake. More recently, the study by Poortmans and Dellalieux [6] investigated bodybuilders and other well-trained athletes with high-and medium-protein intake, respectively. The athletes underwent a 7-day nutrition record analysis as well as blood sample and urine collection to determine the potential renal consequences of a high protein intake. The data revealed that despite higher plasma concentration of uric acid and calcium, bodybuilders had renal clearances of creatinine, urea, and albumin that were within the normal range. To conclude, it appears, at least in the short term, that protein intake under 2.8 g/kg does not impair renal function in well-trained athletes. More recently, Knight et al. [7] determined whether protein intake influences the rate of renal function change in women over an 11-year period. 1624 women enrolled in the Nurses' Health Study who were 42–68 years of age in 1989 and gave blood samples in 1989 …