Effects of acute protein loads of different sources on renal function of patients with diabetic nephropathy.

Abstract

To evaluate effects of acute loading of different proteins on renal function, glomerular filtration rate (GFR), albumin excretion rate (AER), and concentrations of plasma amino acids, 11 normal volunteers and 20 diabetic patients were studied before and after eating 1.0 g/kg body weight of either tuna fish meal or bean curd on separate days. In normal subjects, the mean baseline GFR was 115.8+9.5 ml/min/1.73 m2, and the mean GFRs after ingestion of tuna fish meal were 134.1± 15.5 (1 hr), 146.2 + 18.8 (2 hr), and 157.8±21.2 (3 hr), respectively. GFR did not significantly increase in normal subjects after ingestion of bean curd. GFR in diabetic patients with normoalbuminuria after ingestion of each protein was similar to the response in normal subjects. In diabetic patients with microalbuminuria, GFR did not significantly increase after ingestion of each protein. In diabetes with macroalbuminuria, GFR decreased after ingestion of tuna fish meal and did not significantly change after intake of bean curd. In both normal subjects and diabetic patients, urinary AER did not increase after each kind of protein loading. Plasma concentrations of alanine, glycine, and arginine, known to induce glomerular hyperfiltration, increased to a greater degree after ingestion of tuna fish meal than after administration of bean curd. These findings suggest that responses of GFR to acute protein loading may differ according to the amino acid composition of the protein ingested and to the stage of diabetic nephropathy. Diabetic nephropathy ; GFR ; glomerular hyperfiltration ; proteins of different sources ; composition of amino acids An elevated glomerular filtration rate (GFR) in uncomplicated type 1 (insulin dependent) diabetic patients has been confirmed for many years. As to the clinical significance of this phenomenon, Mogensen (1971Mogensen ( , 1976 recently reported that glomerular hyperfiltration in type 1 diabetes with an early stage of diabetic nephropathy might play an important role in subsequent development of late diabetic nephropathy.Although the exact mechanism that induces glomerular

Animal Versus Plant Protein Meals in Individuals With Type 2 Diabetes and Microalbuminuria

“…Previous studies that demonstrated renal effects of protein in the diet used differing populations of subjects. Nakamura et al (14) found, in acute feeding studies, that individuals with type 1 or type 2 diabetes and microalbuminuria did not have a significant change in GFR during 3 h after eating tuna fish or bean curd (tofu). In nondiabetic individuals and individuals with diabetes and normoalbuminuria, there was a significant increase in GFR after tuna fish but not after tofu (12).…”

“…Studies performed in normoalbuminuric individuals with diabetes have suggested that changing the composition of the diet by altering the source of protein from animal to plant, either acutely in the setting of a standard test meal (12) or for up to 4 weeks (13), might produce beneficial renal effects. However, in another acute study, individuals with type 1 or type 2 diabetes and microalbuminuria showed no significant change in renal function when given plant-based protein (PP) versus animal-based protein (AP) (14).…”

“…Studies performed in normoalbuminuric individuals with diabetes have suggested that changing the composition of the diet by altering the source of protein from animal to plant, either acutely in the setting of a standard test meal (12) or for up to 4 weeks (13), might produce beneficial renal effects. However, in another acute study, individuals with type 1 or type 2 diabetes and microalbuminuria showed no significant change in renal function when given plant-based protein (PP) versus animal-based protein (AP) (14).In addition to having a possible renal benefit, plant-based diets (particularly those using soy) have been reported to reduce total and LDL cholesterol (15-17).Our hypothesis was that a diet based on PP would have beneficial renal and lipid effects compared with a diet with a majority of its protein from animal sources. The mechanism, if these benefits could be confirmed, might be attributed to differences in the distribution of amino acids between diets.…”

Glomerular filtration response to acute loading with protein from different sources in healthy volunteers and diabetic patients.

“…These facts led us to investigate whether diabetic nephropathy was influenced by the quality as well as the quantity of dietary protein. Our previous study showed that acute administration of vegetable proteins (at least of cooked soybean protein) did not increase GFR (Nakamura et al 1989). In addition, the present study demonstrates that ingestion of cheese or egg white does not induce hyperfiltration.…”

“…These findings, together with the finding that low-protein alimentation may have the abovementioned harmful side effects, led us to investigate whether diabetic nephropathy is influenced by the quality as well as the quantity of dietary protein. In a previous report, we examined the influence of proteins from two different sources on renal function in healthy volunteers and diabetic subjects (Nakamura et al 1989). Our study showed that ingestion of cooked soybean protein does not increase GFR.…”