DASH diet, Reduced Rank Regression Dietary Patterns and relations with kidney function in the CHRIS general population study

Background: Chronic kidney disease (CKD) is a growing public health concern, closely linked to aging and chronic conditions such as diabetes, cardiovascular disease, and hypertension. Diet is a modifiable risk factor for kidney function, but evidence on how specific dietary patterns (DPs) relate to kidney health in healthy populations remains limited. To address this, we evaluated associations between DPs and kidney function, considering sex and menstrual status. DPs were derived using both an a priori approach (DASH) and a hybrid method (RRR), capturing established dietary recommendations as well as population-specific behaviours relevant to kidney health. Methods: We analysed cross-sectional data from 6133 healthy adult participants of the Cooperative Health Research In South Tyrol (CHRIS) study. Participants self-reporting previous diagnoses of any kidney disease, hypertension, or diabetes were excluded. Using self-reported food frequency questionnaire data, we derived the DASH-score and two RRR-based sex-specific DP-scores based on nine cardio-renal-metabolic parameters. We applied sex-stratified linear and non-linear models to examine associations with creatinine-based eGFR, including interaction and stratified analyses by menstrual status in females. Results: In males, a DP reflecting high intake of cereals, whole grains, sugar, fruits, and legumes, and low intake of beer, red and processed meat was associated with higher eGFR levels (β = 0.75, p = 0.0001). Similarly, higher adherence to the DASH diet was also positively associated with eGFR (β = 0.64, p = 0.0029). In females, the associations varied by menstrual status. Among those with ceased menstruation, a DP reflecting low intake of meat, spirits, and refined grains, and high intake of whole grains and dairy products was associated with higher eGFR (β = 1.11, p = 0.0049). In females still experiencing regular menstruation, a DP reflecting high intake of beef, nuts, beer, and legumes, and low intake of refined grains was associated with lower eGFR (β = −0.43, p = 0.0326). No association was observed with the DASH score in females. Conclusions: The DASH-style diet is associated with better kidney function in males, but not in females. Identifying sex-specific kidney function-oriented DPs using RRR provides new insights into the diet-eGFR relationship, suggesting potential effect modification by menstrual status. Supplementary information: The online version contains supplementary material available at 10.1186/s12882-026-04896-z.