How effective is the dash diet in Hypertension?
Americans, besides consuming excess salt, eat foods high in saturated fats and low in fiber and potassium. Low dietary potassium predisposes to sodium retention, volume expansion, and hypertension. Potassium supplementation can decrease blood pressure in hypertensive patients. The mechanism by which fiber may prevent hypertension is not well delineated, although a meta-analysis showed that diets supplemented by fiber lower blood pressure (–1.13/–1.26 mm Hg). The DASH diet emphasizes fruits and vegetables and low-fat foods. During an 8-week trial, the DASH diet, in patients with and without hypertension, lowered blood pressures by −5.5/–3 mm Hg. If the DASH diet is coupled with low sodium intake (1.5 g daily), blood pressures will decrease by –8.9/–4.5 mm Hg compared to an average American diet. Unfortunately, the National Health and Nutrition Examination Survey (NHANES) data reveal that nearly 91% of Americans consume more than 2300 mg of sodium daily. Only 1.2% patients who would benefit from reducing dietary sodium to ≤1.5 g (i.e., African Americans, patients ≥51 years, or patients with diabetes mellitus, hypertension, or chronic kidney disease) actually restrict dietary sodium appropriately. Over 60% of these patients consume more than 3 g of sodium daily. DASH dietary instructions have been published for easy reference.
While the appropriateness of the DASH diet for chronic kidney disease patients has not been studied extensively, a small pilot study of 11 patients recently showed that the DASH diet is safe for patients with moderate kidney disease (i.e., an estimated glomerular filtration rate of 30 to 59 mL/min per 1.73 m 2 ). No significant hyperkalemia occurred during the 2-week study, and nighttime systolic blood pressure decreased by 5.3 mm Hg.
