Is It Time to Abandon the Nutrient-Based Renal Diet Model?

David E. St-Jules; Denis Fouque

Disclosures

Nephrol Dial Transplant. 2021;36(4):574-577. 

In This Article

Abstract and Introduction

Introduction

The traditional renal diet is logical, but perhaps not biological. In this issue of Nephrology Dialysis Transplantation, Gonzalez-Ortiz et al. present findings from cross-sectional analyses that add to the growing body of literature.[1] The analysis fails to support the theory that diet-related complications in hemodialysis (HD) patients are caused by diet-derived nutrient imbalances.[2–4] In particular, the renal dietary pattern for HD is designed to be low potassium, low phosphorus and high protein, with the understanding that this would help to prevent and treat hyperkalemia, hyperphosphatemia and protein–energy wasting (PEW), respectively.[5]

The approach used to develop the renal diet was similar to that used to prevent nutrient imbalances in the food guide.[6] First, prescriptions were established for key nutrients.[7] Then, the balance of food groups and variety of food choices within each food group were determined based on their nutrient composition.[5] The resultant HD diet restricts many high-potassium and high-phosphorus plant foods, and promotes animal-based protein foods. Regarding the latter, the 1993 National Renal Diet food guide produced by the American Dietetic Association Renal Practice Group advised dialysis patients to 'eat all the unsalted meats, fish, and poultry, or eggs you want'.[8] The study by Gonzalez-Ortiz et al. found that tertiles of the Healthy Plant-Based Diet Score, an index of plant intake, were not associated with serum potassium and phosphorus concentrations, or malnutrition inflammation score in HD patients.

As noted by Gonzalez-Ortiz et al., it is possible that the nutrient-based renal diet is efficacious for managing these conditions, but cannot be detected in observational studies using standard dietary assessment methods because of measurement error related to misreporting, and the effects of food processing and preparation, which can concentrate, dilute, add and remove nutrients. However, another possibility is that the assumptions underlying the nutrient-based model are incorrect, in which case, dietary restrictions may be an unnecessary burden in HD patients that could contribute to poor health outcomes.

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