Associations between dietary patterns and kidney health assessed in the population-based CHRIS study using reduced rank regression

Objective: While diet plays a key role in CKD management, the potential for diet to impact CKD prevention in the general population is less clear. Using a priori knowledge, we derived disease-related dietary patterns (DPs) through reduced rank regression (RRR) and investigated associations with kidney function, separately focusing on generally healthy individuals and those with self-reported kidney diseases, hypertension or diabetes mellitus. Methods: 8,686 participants from the population-based Cooperative Health Research in South Tyrol (CHRIS) study were split into a group free of kidney disease, hypertension and diabetes (n=6,133) and a group with any of the three conditions (n=2,553). Diet was assessed through the self-administered GA2LEN food frequency questionnaire (FFQ) and DPs were derived through RRR selecting FFQ-derived sodium, potassium, phosphorus and protein intake as mediators. Outcomes were creatinine-based estimated glomerular filtration rate (eGFR), urinary albumin-to-creatinine ratio (UACR), CKD and microalbuminuria. Multiple linear and logistic models were used to assess associations between RRR-based DPs and kidney outcomes separately in the two analytic groups. Results: We identified three DPs, where high adherence reflected high levels of all nutrients (DP1), high potassium-phosphorus and low protein-sodium levels (DP2), and low potassium-sodium and high protein-phosphorus levels (DP3), respectively. We observed heterogeneous associations with kidney outcomes, varying by analytic group and sex. Kidney outcomes were much more strongly associated with DPs than with single nutrients. Conclusion: RRR is a feasible approach to estimate disease-related DPs and explore the combined effects of nutrients on kidney health. Heterogeneous associations across kidney outcomes suggest possible specificity to kidney function or damage. In individuals reporting kidney disease, hypertension or diabetes, specific dietary habits were associated with better kidney health, indicating that disease-specific dietary interventions can be effective for disease control.