Almost 50 million Americans (out of 285 million) have high blood pressure , or hypertension. Blood pressure is measured as the systolic pressure over the diastolic pressure in millimeters of mercury (mm Hg). Hypertension is defined as a blood pressure (BP) of 140/90 mm Hg or higher. The risk of high blood pressure increases with age so that more than half of Americans aged 60 or older are hypertensive.

Hypertension is the primary risk factor for stroke , and is also a major risk factor for heart disease . But even blood pressure below 140/90 mmHg increases risk of cardiovascular disease. In fact, most patients with stroke and heart disease have blood pressure in the normal to high-normal range of 120/80 to 139/89 mm Hg. (An optimal blood pressure is below 120/80 mm Hg.)

The Dietary Approaches to Stop Hypertension (DASH) diet , which emphasizes consumption of fruits, vegetables and low-fat dairy products and reduces fats, red meat, and sweets, has been shown to lower blood pressure, but only under experimental conditions. It has also been established that weight loss, reduced sodium intake, increased physical activity, and limited alcohol consumption are capable of lowering blood pressure. But no studies have shown the effects of actually implementing these recommendations simultaneously.

In a study published in the April 23/30, 2003 Journal of the American Medical Association , researchers found that individuals with or without hypertension can dramatically reduce their blood pressure levels through a combination of weight loss, exercise, reduced salt intake, and the DASH diet.

About the Study

The researchers enrolled 810 adults at four clinical centers between January 2000 and June 2001. The participants had an average age of 50 years; 62% were women; 34% were African American. All participants had normal to mildly elevated blood pressure or Stage 1 hypertension (systolic BP 120–159 mm Hg; diastolic BP 80–95 mm Hg), and none were taking antihypertensive medications.

The study subjects were broken up in into three groups:

  • Advice Only Group : Received one 30-minute session with a registered dietician who offered general advice and printed educational materials on lowering BP, including weight loss, sodium intake, physical activity, and the DASH diet
  • Established Group : This group had 18 counseling sessions over six months about established lifestyle changes for lowering BP, including weight loss, reducing salt intake, and increasing physical activity. The group was also asked to try to meet the following goals over the subsequent six months:
    • Weight loss of at least 15 pounds
    • At least 180 minutes per week of moderate-intensity exercise
    • No more than 100 mEq sodium (equivalent to about 2.3 grams) per day
    • No more than two alcoholic drinks per day for men; one for women
  • Established Plus DASH : This group received counseling sessions and set goals identical to the established group. They also received advice on following the DASH diet.

At six months, the researchers measured the participants’ blood pressure. They also measured weight loss, fitness levels, and changes in dietary patterns.

The Findings

At six months, blood pressure declined in all three groups, but the decline was significantly greater in the Established and Established Plus DASH groups. Systolic blood pressure declined by an average of 11.1 mm Hg in the Established Plus DASH group, 10.5 mm Hg in the Established group, and by 6.6 in the Advice Only group. Diastolic blood pressure declined on average by 6.4 mm Hg in the Established Plus DASH group, by 5.5 in the Established group, and by 3.8 mm Hg in the Advice Only group.

The percentage of people with hypertension declined over six months from 37 to 12 in the Established Plus DASH group, from 37 to 17 in the Established group, and from 38 to 26 in the Advice Only group. At the end of the six months, 19% of the Advice Only group, 30% of the Established group, and 35% of the Established Plus DASH group had optimal blood pressure.

In addition, significant weight loss occurred in all groups, fruit and vegetable intake increased significantly in the Established Plus DASH group compared to the other two groups, and participants in the Established and Established Plus DASH groups had significantly improved fitness test scores at the end of the study.

How Does This Affect You?

According to the study, lifestyle changes can effectively reduce blood pressure, even in individuals without hypertension. The results also provide additional evidence for the effectiveness of the DASH diet in the context of other, “real world” health behaviors.

In addition, the researches showed that with some guidance, patients have the capacity to successfully implement multiple lifestyle changes, at least for six months. Even participants in the Advice Only group managed to lower their blood pressure and lose weight. This suggests that even minimal physician counseling regarding blood pressure reduction can produce measurable, albeit short-term, results.

It is important to note that these promising results are tempered by the fact that the researchers did not address the question of whether lifestyle change directly reduces the risk of disease. While it is reasonable to assume that lowering blood pressure to the degree demonstrated here would reduce the risk of stroke and heart disease, this study cannot make that claim. It takes years, even decades, of blood pressure control to affect cardiovascular risk. Six months is simply not long enough to show such an effect.