Effect of low-protein diet on kidney function and nutrition in nephropathy: A systematic review and meta-analysis of...

The effects of low-protein diet (LPD) on kidney function and nutrition in nephropathy are so far unclear.

To investigate the effect of LPD on kidney function and nutrition.

PubMed, Embase and Cochrane library up to January 2019 and references of retrieved relevant articles.

Twenty-nine studies with 1784 individuals in the LPD arm and 1782 individuals in the normal protein diet were identified. Compared with normal protein diet, LPD significantly reduced BUN (WMD -20.756 mg/dl; 95% CI: -33.969 to -7.544 mg/dl; P = 0.002), UREA (WMD -1.400 g/24 h; 95% CI: -1.713 to -1.088 mmol/L; P < 0.001), proteinuria (WMD -0.416 g/24 h; 95% CI: -0.715 to -0.117 g/24 h; P = 0.006), body weight (WMD -2.757 kg; 95% CI: -3.890 to 1.623 kg; P < 0.001) and BMI (WMD -0.646 kg/m²; 95% CI: -1.068 to -0.223 kg/m²; P = 0.003). Dose-response analysis showed that reduction of protein intake by 0.1 g/kg/d was associated with a 0.68009 kg, 0.08771 kg/m², 0.27147 g/L and 0.00309 g/24 hS reduction in body weight, BMI, ALB and Proteinuria, associated with a 0.135289 ml/min/1.73 m² increase in GFR. The effects of LPD were more obvious on aged, obesity, moderate or severe renal impairment and DN patients.

Low-protein diet was significantly associated with improvement of nephropathy, but LPD increases the risk of malnutrition such as BMI. The present meta-analysis provides evidence that LPD was associated with malnutrition, and high-quality RCTs with multi-center and large simple-size should be performed to confirm the present findings.