Table 2.

Recent observational studies about high protein diet on renal function.

References	Sample size	Mean age (years)	Duration (years)	HP diet	Baseline eGFR (ml/min per 1.73 m2)	Renal function changes
Knight et al. 2003[11]	1,624	55.4	11	Divided into quintiles (5th group: 93 g/day)	Normal: >80 Mild CKD: 55–80	HP was not associated with eGFR decline in normal renal function. However, it was associated with accelerated eGFR decline in mild CKD, particularly with high intake of non-dairy animal protein.
Halbesma et al, 2009[12]	8,461	49.8	6.4	Divided into quintiles (5th group: 1.42–3.27 g/kg/day)	mean 80.6	There was no association of protein intake and rate of eGFR changes.
Lin et al, 2011[15]	3,121	67	12	Divided into quartiles (4th group: 78 g/day)	median 76	HP was directly associated with microalbuminuria (highest quartile vs. lowest OR, 2.17; 95% CI, 1.18–3.66; p=0.01), and rapid eGFR decline (OR, 1.77; 95% CI, 1.03–3.03).
Dunkler et al, 2013[16]	6,123	66.6	5.5	High: 0.96 g/kg/day Low: 0.36 g/kg/day	mean 74.3	Lower total and animal protein intake was associated with increased risk of CKD (highest tertile vs. lowest for total protein OR, 1.16; 95%CI, 1.05–1.30)
Cirillo et al, 2014[13]	1,522	49.3	12	High ≥ 1.6g/kg/day Low< 1.0g/kg/day	mean 84.0	HP was associated cross-sectionally with higher eGFR, but longitudinally with greater eGFR decline over time.
Lew et al, 2016[14]	60,198	56.5	15.5	Divided into quartiles (4th group: 65.3 g/day)	n.d	Protein intake amount, especially consumption of red meat was strongly associated with ESRD risk.

Abbreviations: CKD-chronic kidney disease; HP-high protein diet; eGFR-estimated glomerulofiltration rate; OR-odd ratios; CI-confidence interval; yr-year; n.d-not described; ESRD-end stage renal disease