From The April 2001 Issue of Nutrition Science News

Has Hypertension Met Its Match?

A healthy overall diet as well as a low-sodium diet lower blood pressure, according to two major government-funded studies: Dietary Approaches to Stop Hypertension (DASH) and the Sodium Collaborative Research Group. Frank Sacks, M.D., and colleagues at Harvard Medical School in Boston studied the effect of different levels of dietary sodium, in conjunction with the DASH diet, which is rich in vegetables, fruits, and low-fat dairy products and also includes fish, nuts, poultry, and whole grains.

The prospective crossover study assayed 412 participants, who were provided with all the food they consumed during a three-month period. Subjects were at least 22 years old; half were male, half were black; and all had systolic blood pressures between 120 and 159 mmHg and diastolic between 80 and 95 mmHg, which are considered normal-to-high levels but not severely abnormal. For two weeks, all participants ate a standard American diet. Then they were randomly assigned to either continue the typical American diet or eat the DASH diet—higher in produce, lower in dairy fat. Both diets were provided at three different sodium levels: 140 mmoL/day (the average U.S. level), 100 mmoL/day (officially recommended upper limit), or 65 mmoL/day. Participants switched their assigned sodium levels every 30 days.

Lower sodium intake resulted in lower blood pressure on both diets. Participants eating the DASH diet had lower blood pressure at every sodium level compared with those eating the standard American diet. The combination of the two interventions—low sodium and the DASH diet—lowered blood pressure the most. During the study, 36 people on the control diet registered very high blood pressure (systolic greater than 170, or diastolic greater than 105) compared with six on the DASH diet, and, notably, none of the subjects eating the low-sodium DASH diet.

These study results indicate that reducing sodium lowers blood pressure in people with or without hypertension. The researchers concluded that the recommended sodium intake, already substantially lower than the average intake, should be lowered further, and that more low-sodium products should be made available. These findings can help doctors advise patients on their diets and reduce the number of heart attacks and strokes in this country.

—New England Journal of Medicine 2001 Jan 4;344(1):3.