Effects of dietary animal or plant protein on risk of kidney stone formation in adults without urinary calculi

Objective To investigate whether dietary animal or plant protein can affect the propensity for kidney stone formation.Methods The study was a prospective, single-center, randomized cross-over controlled trial.Seven healthy male adults were recruited and randomized into groups A and B.Group A received an animal protein diet for 7 days, followed by 7-day, free-living diet wash-out period and plant protein diet for another 7 days.The dietary scheme of group B was opposite to that of group A.24 h urine collections were obtained at Day 7/21.24 h urinary excretion of sodium(Na), potassium(K), calcium(Ca), phosphorus(P), magnesium(Mg), urea nitrogen, creatinine, uric acid, sulfate, citrate, oxalate and urinary pH were measured.The supersaturation of urinary CaOx, Brushite, uric acid and sodium uric acid were calculated by EQUIL 2 software.Results Compared with baseline and plant protein diet, 24 ho urinary Ca(4.75±1.29) μmol vs (2.96±1.66) μmoland Mg(3.70±1.35) μmol vs (3.16±1.22) μmol, uric acid(4184±1032) μmol vs (2997±616) μmoland creatinine(14163±3685) μmol vs (7668±2569) μmolsignificantly spiked after an animal protein diet.Urinary Na(74.86±36.26) μmol vs (117.46±49.28) μmoland Cl(89.00±35.67) μmol vs (117.11±47.20) μmoldramatically declined on a plant protein diet.After receiving protein diets from different sources, no significant differences existed in urinary SS CaOx, SS Bru, SS UA and SS SUA between animal and plant protein diets.Conclusion Animal protein intake produces an elevation of urinary calcium, uric acid and magnesium excretion.Dietary plant protein decreases urinary sodium excretion.However, no variations exist in urinary CaOx, Brushite, UA supersaturation on either animal protein or plant protein diet.