The
biological consequences of chronic consumption of
Maillard reaction products (MRPs) on renal function in health and renal disease are still incompletely understood. We investigated the metabolic and renal effects of a diet with varying MRP content in healthy and subtotally nephrectomized rats. Male Wistar rats were subjected to
sham operation (control, C, n = 12), or to 5/6
nephrectomy (5/6NX, n = 12). Both groups were randomized into subgroups and pair-fed with either a MRP-poor or -rich diet for six weeks. The diet was prepared by replacing 5% or 25% of wheat
starch by bread crust (BC). In spite of pair-feeding, the rats on the 25% BC diet gained more
body weight (C: 183 +/- 6 g; C + 5%
BC: 197 +/- 7 g; C + 25% BC: 229 +/- 6 g [P < 0.05]; 5/6NX: 165 +/- 10 g; 5/6NX + 5% BC: 202 +/- 3 g; 5/6NX + 25% BC: 209 +/- 8 g [P < 0.05]) and had a higher organ weight (heart, liver, lung, kidney/remnant kidney). Bread crust-enriched diet induced
proteinuria (C: 15 +/- 5 mg/24 h; C + 5% BC: 19 +/- 4; C + 25% BC: 26 +/- 3 [P < 0.05]; 5/6NX: 30 +/- 7 mg/24 h; 5/6NX + 5% BC: 47 +/- 9; 5/6NX + 25% BC: 87 +/- 19 [P < 0.01]) and a rise in urinary
transforming growth factor beta(1) excretion (C: 0.4 +/- 0.1 ng/24 h; C + 5% BC: 0.6 +/- 0.1; C + 25% BC: 1.2 +/- 0.3; 5/6NX: 0.5 +/- 0.1 ng/24 h; 5/6NX + 5% BC: 0.9 +/- 0.1; 5/6NX + 25% BC: 1.6 +/- 0.2 [P < 0.01]). Plasma
creatinine or
creatinine clearance were not affected significantly. In conclusion, our data suggests that long-term consumption of a diet rich in MRPs may lead to damage of the kidneys.