Dietary inflammatory index and the aging kidney in older women: a 10-year prospective cohort study

Purpose: Chronic inflammation plays a role in the pathogenesis of age-related renal disease and the diet can moderate systemic inflammation. The primary objective of this study was to examine the associations between a dietary inflammatory index (DII^®) score and renal function, the trajectory of renal function decline, and renal disease-related hospitalizations and/or mortality over 10 years. Methods: The study was conducted in 1422 Western Australian women without prevalent chronic kidney disease and aged ≥ 70 years. Baseline dietary data, obtained from a validated food frequency questionnaire, were used to calculate a DII score for each individual. Results: In this cohort, the mean [range] DII score was 0.19 [− 6.14 to 6.39]. A higher DII score was associated with poorer renal function at baseline and a greater renal function decline over 10 years; after multivariable adjustments, a one-unit higher DII score was associated with a 0.55 mL/min/1.73 m² lower eGFR at baseline (p = 0.01) and a 0.06 mL/min/1.73 m² greater annual decline in eGFR over 10 years (p = 0.05). Restricted cubic splines provide evidence of a non-linear association between baseline DII score and risk of a renal disease-related event. Compared to participants in the lowest quintile, those in the highest quintile of DII score were at a higher risk of experiencing a renal disease-related event (adjusted HR 2.06, 95% CI 0.97, 4.37). Conclusion: Recommending an increased consumption of foods with a higher anti-inflammatory potential could form part of a multifaceted approach to reduce the risk of renal disease through diet and lifestyle changes.