Background: Although it is well-known that the restriction of protein intake in chronic renal failure (CRF) is effective in slowing the progressive loss of renal function, recent randomized controlled trials have not consistently shown a beneficial effect on CRF. There is controversy regarding the amount of protein intake that results in this effect. In this study, various amounts of protein intake were compared in CRF patients due to chronic glomerulonephritis (CGN) in order to explore effective restriction of dietary protein.
Methods: CGN patients (121 in total) with a serum creatinine level of 6 mg/dl were studied. They were subdivided into six groups depending on their protein intake: 0.3 g/kg BW/day (0.3 g), 0.4, 0.5, 0.6, 0.7, and > or =0.8 g (control group C). Deterioration of renal function was evaluated by the mean rate of decline in creatinine clearance, and the amount of protein intake was estimated on the basis of the urea nitrogen appearance rate in a 24-hour urine sample.
Results: There was no significant difference in the suppression of the progression of renal dysfunction in the 0.6- and 0.7-g groups. However, significant suppression was observed in the 0.5-, 0.4-, and 0.3-g groups in comparison with those that received more than 0.6 g (p < 0.05). The renal survival rate in the groups that received less than 0.5 g was higher than that in the groups that received more than 0.6 g (p < 0.05). Malnutrition was not observed in all patients studied.
Conclusion: We found that a protein intake of more than 0.5 g/kg BW/day is not effective in suppressing further deterioration of renal function in CRF resulting from CGN.