DASH is more effective in lowering blood pressure in metabolic syndrome patients than potassium, magnesium and fiber supplements

Abstract

We found that the DASH Eating Plan lowered blood pressure (BP) in obese hypertensives. The reduction in BP correlated inversely with the increase in plasma anti-oxidant capacity, although others have attributed BP changes to the high K+, Mg++ and/or Ca++ content of DASH. In this study, the BP lowering effects were examined of supplementing the usual diet with K+, Mg++, and fiber vs DASH in lean normotensives and obese, metabolic syndrome patients. Seven obese [BMI 37.2±5.3] volunteers, 38.7±9.2 [SD] years old, 2:AA, 5:C, 3:M, 4:F, with the metabolic syndrome and 8 lean healthy subjects [BMI 22.3±1.4, age 35.5±7.7 yrs, 2:AA, 6:C, 2:M, 6:F]. All subjects initially followed a standardized usual diet (low anti-oxidant) for 3 weeks. They were randomized to follow either the same diet supplemented with K+, Mg++, and fiber to match the content of DASH or the DASH Eating Plan for 3 weeks each followed by a 3-week crossover to the other diet. All 3 diets were isocaloric and matched for Na+ and Ca++ content. Subjects prepared their own meals. Dietary adherence was determined by digital photographs of meals and beverages and food records. At the end of each 3-weeks, 6 resting supine BP readings were taken by mercury sphygmomanometry on the left arm; the first value was deleted and last five were averaged. Compared to the usual diet, BP did not decline significantly in either group when the usual diet was supplemented with ∼2000 mg K+ and 300 mg Mg++ daily to match DASH but declined on DASH in metabolic syndrome (−5.3/−4.6 mmHg, p=0.02/0.03) but not control subjects (−3.2/−2.2 mmHg, NS/NS). The data suggest the DASH Eating Plan lowers BP more effectively in obese, metabolic syndrome patients than supplementing the usual diet with K+, Mg++ and fiber to match DASH. These findings raise the possibility that other components of the diet, e.g., antioxidant / bioflavonoids, contribute to the BP benefits of the DASH Eating Plan. See Table 1.