Protein. How much is too much?

There is emerging evidence to suggest that increasing your protein intake to maintain your muscle mass as your age will reduce the likelihood and severity of frailty, falls and fractures in later life(1), but what about the effect on your kidneys? As ageing is associated with a decline in kidney function, is there any evidence that an increase in dietary protein does more harm than good?

Two large scale studies of women aged 42 to 79 found no evidence of any link between increased dietary protein intake and impaired kidney function for those with normal renal function.(2.3) This held regardless of age, BMI or general health status in one of the studies, while in the other long-term 11-year study, there was an association between higher dietary protein intake (especially of non-dairy animal protein) and accelerated renal function decline for those with existing impaired renal function.

A third study(4) looked at the available evidence for healthy individuals, and, defining high protein as 1.5g protein per kg body weight per day, concluded that:

“Although excessive protein intake remains a health concern in individuals with pre-existing renal disease, the literature lacks significant research demonstrating a link between protein intake and the initiation or progression of renal disease in healthy individuals. More importantly, evidence suggests that protein-induced changes in renal function are likely a normal adaptative mechanism well within the functional limits of a healthy kidney.”

As with any change to exercise or diet, the recommendation is to check with your doctor first.


1. Bauer et al 2013 PROTAGE Recommendations JAMDA 14 (2013) 542-559

2. Beasley JM, Aragaki AK, LaCroix AZ, et al. Higher biomarker-calibrated protein

intake is not associated with impaired renal function in postmenopausal

women. J Nutr 2011;141:1502e1507.

3. Knight EL, Stampfer MJ, Hankinson SE, et al. The impact of protein intake on

renal function decline in women with normal renal function or mild renal

insufficiency. Ann Intern Med 2003;138:460e467

4. Martin, William F, Lawrence E Armstrong, and Nancy R Rodriguez. “Dietary Protein Intake and Renal Function.” Nutrition & Metabolism 2 (2005): 25. PMC.