Low-sodium DASH reduces oxidative stress and improves vascular function in salt-sensitive humans

Salt induces oxidative stress in salt-sensitive (SS) animals and man. It is not known whether in SS subjects the low-sodium dietary approaches to stop hypertension (LS-DASH) reduces oxidative stress more than DASH, which is high in antioxidants. To assess the effects of DASH and LS-DASH on oxidative stress, 19 volunteers were studied after 3 weeks of a standardized usual low fruits and vegetables diet (ULFV), followed by 3 weeks on DASH (both diets similar to 120 mmol Na+ per day), then 3 weeks on LS-DASH (60 mmol Na+ per day). SS was defined as systolic blood pressure >= 5 mm Hg lower on LS-DASH than DASH. In SS subjects (N = 9), systolic blood pressure was lower on LS-DASH (111.0 +/- 2.0 mm Hg) than DASH (118.0 +/- 2.2, P<0.01) and ULFV (122.3 +/- 2.7, P = 0.002). In salt-resistant (SR) volunteers (N = 10), systolic blood pressure was lower on DASH (113.0 +/- 1.6) than ULFV (119.0 +/- 1.8, P<0.05) but not LS-DASH (115.7 +/- 1.8). Urine F2-isoprostanes, a marker of oxidative stress, were lower in SS subjects on LS-DASH (1.69 +/- 0.24) than ULFV (3.09 +/- 0.50, P<0.05) and marginally lower than DASH (2.46 +/- 0.44, P<0.20). F2- isoprostanes were not different among the three diets in SR volunteers (2.18 +/- 0.29, 2.06 +/- 0.29, 2.27 +/- 0.53, respectively). Aortic augmentation index, a measure of vascular stiffness, was lower in SS subjects on LS-DASH than either DASH or ULFV, and lower on DASH than ULFV in SR volunteers. In SS but not SR subjects, LS-DASH is associated with lower values for F2- isoprostanes and the aortic augmentation index. The results suggest that LS-DASH decreases oxidative stress, improves vascular function and lowers blood pressure in SS but not SR volunteers. Journal of Human Hypertension (2009) 23, 826-835; doi: 10.1038/jhh.2009.32; published online 30 April 2009