Dietary Plant and Animal Protein Intake and Decline in Estimated Glomerular Filtration Rate Among Elderly Women

A 10-Year Longitudinal Cohort Study

Amélie Bernier-Jean; Richard L. Prince; Joshua R. Lewis; Jonathan C. Craig; Jonathan M. Hodgson; Wai H. Lim; Armando Teixeira-Pinto; Germaine Wong

Disclosures

Nephrol Dial Transplant. 2021;36(9):1640-1647. 

In This Article

Abstract and Introduction

Abstract

Background: Many older women demonstrate an age-related accelerating rate of renal decline that is associated with increased rates of bone disease, cardiovascular disease and mortality. Population-based protein restriction has been studied principally in patients with reduced renal function. In this investigation, we examined the hypothesis of a differential effect of plant-derived protein compared with animal-derived protein on renal function in older women.

Methods: We assessed dietary intake from a validated food frequency questionnaire and the estimated glomerular filtration rate (eGFR) (using the Chronic Kidney Disease Epidemiology Collaboration creatinine and cystatin C equation) at baseline, 5 and 10 years in the Longitudinal Study of Aging Women cohort. We tested the association between plant- and animal-sourced protein intake and kidney function using linear mixed modeling.

Results: A total of 1374 Caucasian women [mean (standard deviation, SD) age = 75 years (2.7) and mean (SD) baseline eGFR = 65.6 mL/min/1.73 m2 (13.1)] contributed to the analysis. The average decline in eGFR was 0.64 mL/min/1.73 m2/year [95% confidence interval (CI) 0.56–0.72]. Higher intakes of plant-sourced protein were associated with slower declines in eGFR after adjusting for covariates including animal protein and energy intake (P = 0.03). For each 10 g of plant protein, the yearly decline in eGFR was reduced by 0.12 mL/min/1.73 m2 (95% CI 0.01–0.23), principally associated with fruit-, vegetable- and nut-derived protein. The intake of animal protein was not associated with eGFR decline (P = 0.84).

Conclusions: Older women consuming a diet that is richer in plant-sourced protein have a slower decline in kidney function. These data extend support for the health benefits of plant-rich diets in the general population to maintain kidney health.

Introduction

Chronic kidney disease (CKD) is a growing public health concern responsible for 956 000 deaths globally in 2013, compared with 409 000 in 1990.[1] With population aging and rising rates of diabetes, obesity and hypertension (HTN), the need for renal replacement therapy is expected to double by 2030.[2] The consequences of CKD extend well beyond the loss of kidney function as it contributes to cardiovascular disease, cognitive decline, bone and mineral disorders, and loss of quality of life.[3] Public health-oriented prevention of CKD progression is key to face this expanding public health concern.

Population studies of individuals without risk factors for renal impairment have identified a progressive reduction in renal function with age[4] and older women developing CKD face an increased burden of comorbidities.[5] Thus, population-based interventions aimed at reducing the loss of kidney function in this population are attractive. Protein restriction has long been advocated. Indeed the current Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend against high protein intake (>1.3 g/kg/day) in people with CKD who are at risk of progression.[6,7] However, evidence suggests that the origin of protein may be an influential factor for kidney function. Proteins from plants reduce acidosis while animal proteins contribute to the acid-load and can induce hyperfiltration and proteinuria.[8–10] The evidence for this effect in the general population is mostly theoretical and observational studies are often limited to a baseline assessment of diet even though diet and kidney function are dynamic processes that are better evaluated longitudinally across repeated measurements.

Few studies have focused on older patients with Stages 2 and 3 progressive kidney disease.[11] Thus, we aimed to assess the association between the source, plant or animal, of dietary protein and the age-related decline in kidney function to examine the hypothesis of a differential effect of plant-derived protein compared with animal-derived on renal function. We used data from a cohort study of older women with repeated assessments of food intake and renal function. Our intent was to refine guidelines advising limiting protein intake in this population.

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