DOCTOR'S ARCHIVE

Salt, DASH, and Blood Pressure

Medical Author: Dwight Makoff, M.D.
Medical Editor: Leslie J. Schoenfield, M.D., Ph.D.

Patients often ask what changes in life style can contribute to improving their blood pressure. In response, we doctors often recommend that reducing body weight, decreasing intake of dietary salt, and limiting consumption of alcohol can be beneficial. However, we need to now also consider the increasingly publicized DASH diet. This diet can bring about a reduction in blood pressure in people with normal blood pressure or high blood pressure (hypertension). Furthermore, when combined with a restricted dietary intake of salt, DASH actually has an additive effect in reducing the blood pressure.

DASH stands for "Dietary Approaches to Stop Hypertension." This diet is rich in fruits, vegetables, and grain (cereal) products. It also includes low-fat and fat-free dairy products, fish, legumes (e.g., peas and beans), nuts, poultry, and lean meats. The diet contains only small amounts of red meat, sweets, and sugar-containing beverages and is low in fat. The DASH diet is higher in potassium, calcium, magnesium, dietary fiber, and protein than the typical American diet.

The average intake of salt (sodium chloride) in the U.S. is approximately 9 grams per day, which contains 150 mmol, or 3.5 grams, of sodium per day. Reductions in the daily sodium intake to 100 mmol (2.3 grams), and then to 50 mmol (1.2 grams), lead to sequential reductions in blood pressure. When dietary salt restriction is combined with the DASH diet, an even greater reduction in blood pressure occurs at each level of sodium intake. The studies have indicated that the groups who have the best response to this combined approach are people older than 45 years, patients with hypertension, and African-Americans. Importantly, it is also thought that younger people with normal blood pressures who follow these combined dietary guidelines may develop less hypertension as they get older.