From the Guidelines
Poor nutritional status can indeed cause a decline in estimated Glomerular Filtration Rate (eGFR). According to the most recent and highest quality study, a dietary protein intake of 0.8 g/kg body weight per day is recommended to slow GFR decline 1. Malnutrition affects kidney function through several mechanisms, including protein-energy malnutrition, which can lead to decreased muscle mass and altered eGFR calculations. Severe protein restriction or deficiency can impair kidney structure and function directly. Micronutrient deficiencies, particularly vitamin D, can negatively impact kidney health by affecting calcium-phosphorus metabolism and increasing inflammation. Dehydration associated with poor nutrition reduces renal perfusion, leading to decreased filtration.
Key considerations for patients with declining eGFR include:
- Balanced protein intake, typically 0.8-1.0 g/kg/day for early CKD
- Adequate hydration
- Restriction of dietary sodium to <2,300 mg/day to control blood pressure and reduce cardiovascular risk
- Individualization of dietary potassium to manage serum potassium concentrations
It is essential to note that reducing dietary protein below the recommended daily allowance of 0.8 g/kg/day is not recommended, as it does not alter blood glucose levels, cardiovascular risk measures, or the course of GFR decline 1. Additionally, higher levels of dietary protein intake (>20% of daily calories from protein or >1.3 g/kg/day) should be avoided, as they have been associated with increased albuminuria, more rapid kidney function loss, and CVD mortality 1. For patients with declining eGFR, nutritional assessment and appropriate dietary interventions should be considered as part of comprehensive kidney care.
From the Research
Association between Poor Nutritional Status and eGFR Decline
- Poor nutritional status has been associated with a decline in estimated Glomerular Filtration Rate (eGFR) in several studies 2, 3, 4.
- A study published in the Journal of Renal Nutrition found that malnutrition risk was significantly associated with decreasing eGFR coefficients and increasing chronic kidney disease (CKD) odds ratios 2.
- Another study published in The British Journal of Nutrition found that diet therapy along with nutrition education can improve renal function in people with stages 3-4 CKD, and that the eGFR increased significantly in the intervention group compared to the control group 3.
- A literature review published in Current Hypertension Reports found that a healthy dietary pattern may lower CKD risk, and that plant-based foods, coffee, and dairy may be beneficial for kidney function 5.
Mechanisms and Factors Involved
- The prognostic nutritional index (PNI), an integrated index of serum albumin and peripheral lymphocyte count, has been found to be associated with renal function changes in the general population, with lower PNI values reflecting poor nutritional status or inflammation 4.
- A high-protein diet has been found to increase eGFR in healthy adults, although the long-term effects of a high-protein diet on kidney function are uncertain 6.
- Other factors, such as meat, fish, dairy, vegetables, fruit, coffee, tea, soft drinks, and dietary patterns, have also been found to be associated with kidney function, although the evidence is not always consistent 5.
Implications for Kidney Function
- The studies suggest that poor nutritional status can contribute to a decline in eGFR, and that improving nutritional status through diet therapy and nutrition education may help to slow or prevent this decline 2, 3, 4.
- A healthy dietary pattern, including plant-based foods, coffee, and dairy, may be beneficial for kidney function, while a high-protein diet may have uncertain long-term effects 6, 5.
- Further research is needed to fully understand the relationships between nutritional status, diet, and kidney function, and to develop effective strategies for preventing or slowing kidney function decline 2, 3, 5, 4.