Skim soy protein enhances GFR as much as beefsteak protein in healthy human subjects

It has been reported that an acute load of beefsteak (200 g) significantly enhanced the glomerular filtration rate (GFR; inulin clearance and creatinine clearance) in healthy human subjects compared to that in the same subjects in the fasted state. However, no comparative study of the effects of the same amount of vegetable protein on GFR has been reported to date.

We attempted to compare changes in the GFR (inulin clearance and creatinine clearance) in six healthy male subjects following consumption of the same amount of beefsteak or baked skim soy with soy sauce (protein, 86.9 g) after fasting. The clearance study was performed by conventional methods. Inulin was measured by the anthrone method. Creatinine was measured by the Jaffe rate assay method. Amino-acid analysis of the beefsteak and baked skim soy with soy sauce was done by acid or hydroxide hydrolysis and an amino-acid analyzer.

A significant enhancement of the GFR (both inulin clearance and creatinine clearance) was observed following acute loading with beefsteak or baked skim soy with soy sauce, compared to the GFR in the fasted state. No significant difference was observed between the results with beefsteak and the results with baked skim soy with soy sauce. Amino-acid analysis revealed that the total amount of three amino acids (glycine, alanine, and arginine; or serine, alanine, and proline) was almost identical in beefsteak (animal protein) and baked skim soy with soy sauce (vegetable protein).

The present study demonstrated that vegetable protein with the same amino-acid composition could enhance the GFR in healthy subjects as much as animal protein.