Renal function and sodium intake: A review. 


Recent guidelines propose a dietary sodium intake of less than 2.0 g or even less than 1.5 g daily for patients with chronic kidney disease (CKD), report Japanese nephrologists at the Teikyo University School of Medicine in Tokyo. However, other topical studies have failed to find robust evidence to support this approach and have even indicated that a sodium intake of less than 1.5 g/d could be potentially harmful. In view of the ongoing controversy, the aim of the present quantitative review of the literature was to assess currently available evidence. Data were extracted from 36 studies (11 cross-sectional and 5 longitudinal observational studies, 20 intervention trials).
The key findings:
  • In observational studies, renal function as assessed by eGFR, albuminuria, urinary albumin-to-creatinine ratio, CKD, or ESRD yielded insufficient direct evidence for association with sodium intake.
  • Five longitudinal studies did not generate robust evidence that reduction of salt intake would prevent CKD or its progression.
  • The majority of intervention studies failed to provide sufficient information on design, results, and potential sources of bias, resulting in low quality scores.
  • According to intervention studies, eGFR and albuminuria or proteinuria increased with higher salt intake.
This review shows that there is currently no robust evidence to suggest that a long-term reduction of salt intake could or would prevent CKD or delay its progression, summarize the authors. However, they also stress that the present review is mainly based on studies investigating people with only low-grade renal impairment. Therefore, the current findings cannot be extrapolated to patients with moderate or severe chronic kidney disease.
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