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 unknown in SS subjects if the low-sodium Dietary Approaches to Stop Hypertension (LS-DASH) reduces oxidative stress more than DASH, which is high in anti-oxidants. 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 ∼120 mmol Na(+)/day), then 3-weeks on low-sodium (LS)-DASH (60 mmol Na(+)/d). SS was defined as systolic blood pressure ≥5 mmHg lower on LS-DASH than DASH. In SS subjects (N=9), systolic blood pressure was lower on LS-DASH (111.0±2.0 mmHg) 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-isorprostane 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.