DASH diet lowers blood pressure and lipid-induced oxidative stress in obesity

Evidence suggests that obesity may raise blood pressure (BP) through oxidative stress-sensitive mechanisms and that the Dietary Approaches to Stop Hypertension combination diet (DASH-CD) may decrease BP by enhancing antioxidant capacity. To address this question, 12 obese patients with high-normal-to-stage 1 hypertension (hypertensives) and 12 lean normotensives were studied on their usual diets and after following the DASH-CD and a low-antioxidant diet in random sequence for 4 weeks each. Acute oxidative stress was induced by a 4-hour infusion of intralipid and heparin. Ferric-reducing activity of plasma (FRAP) and plasma F-2-isoprostanes were measured as biomarkers of antioxidant capacity and oxidative stress, respectively. BP was lower in obese hypertensives on the DASH-CD than on the usual and low-antioxidant diets (-8.1+/-1.5/-7.4+/-1.6 mm Hg, P<0.05). BP did not change significantly in lean normotensives after 4 weeks on the DASH-CD but tended to rise on the low-antioxidant diet. FRAP on usual diets was higher in lean subjects than in obese subjects. FRAP increased in obese but not lean volunteers on the DASH-CD compared with usual diet, and the group difference disappeared. F-2-isoprostanes increased from baseline during intralipid and heparin in both groups on the low-antioxidant diet but not in obese hypertensives on the DASH-CD. Among free-living obese hypertensives, the DASH-CD raises antioxidant capacity, lowers BP, and reduces oxidative stress induced by acute hyperlipidemia. The findings are consistent with evidence that elevated BP in obese subjects may reflect an imbalance between antioxidant capacity and oxidative stress that is improved by the DASH-CD.