Soy protein increases glomerular filtration rate in dogs with normal or reduced renal function

In mammals, protein ingestion increases the glomerular filtration rate (GFR), an effect which has been incriminated as a risk factor in progression of renal disease. Some studies suggest that a postprandial increase in GFR is absent or mild with vegetable proteins compared to animal proteins. The objective of this experiment was to determine whether vegetable (soy) protein had different effects than animal protein on GFR in dogs with normal or reduced renal function. A trial was conducted in which GFR was measured in four dogs with normal kidney function and seven dogs with reduced renal mass before and after administering protein. Normal dogs were fed four protein sources (casein, soy meal, soy flakes and purified soy protein). Dogs with reduced renal mass were fed three protein sources (casein, purified soy protein and pork liver). All proteins significantly (P < 0.05) increased the GFR in both groups except for casein (P = 0.066) in normal dogs. Proteins did not differ significantly in the magnitude of the increase in GFR that was induced. This study indicates that soy proteins in dogs have the same effect on GFR as animal-source proteins, which is contrary to reports of effects in humans.