LAUSR

Background: The blood pressure-lowering effects of the Dietary Approaches to Stop Hypertension (DASH) dietary pattern and reduced sodium intake are well-established. The effects on other biomarkers related to vascular health are of interest and may assist in explaining cardiovascular benefits of the DASH diet. Objective: We hypothesized that a low-sodium DASH diet improves biomarkers of inflammation [i.e. reduces C-reactive protein (CRP) and soluble urokinase plasminogen activator receptor (suPAR)] and mineral metabolism [phosphorus and fibroblast growth factor-23 (FGF23)]. Methods: We conducted a post hoc analysis of the DASH-Sodium trial using stored frozen serum samples. This controlled feeding study randomized 412 adults to consume either a DASH diet or control diet representative of a typical American diet. Within each arm, participants received three sodium levels (low, intermediate, high) in random sequence, each for 30 days. To maximize contrast, samples collected at the end of the low-sodium DASH (n=198) and high-sodium control (n=194) diets were compared. Between-diet differences in biomarker concentrations were assessed by t-test or Wilcoxon rank sum test for normally distributed and skewed variables, respectively. Results: CRP concentrations did not differ between groups ( P =0.19), but suPAR was higher after the low-sodium DASH diet than the high-sodium control (median, IQR: 2473, 2127-2887 pg/mL vs. 2281, 1929-2679 pg/mL; P =0.003). FGF23 was also higher after the DASH diet (35.9, 26.9-44.8 pg/mL vs. 30.2, 23.5-37.5 pg/mL; P< 0.001). Serum phosphorus was higher after the DASH diet (mean±SEM: 3.5±0.04 mg/dL) versus the control (3.4±0.04 mg/dL; P =0.02). Conclusions: Contrary to our hypothesis, biomarkers of inflammation and mineral metabolism were increased or unchanged by a low-sodium DASH diet compared to a high-sodium control diet. Potential reasons (e.g. short duration of the trial, sodium-specific effects, bioavailable phosphorus-rich dairy intake) require further investigation.