Results of the study, called "Premier," show that rates of high blood pressure dropped from 37 percent to 22 percent among participants who received diet and physical activity counseling.

"These results contain two very good pieces of news for the millions of Americans who have elevated blood pressure," says William Vollmer, PhD, senior investigator at Kaiser Permanente's Center for Health Research and a study co-author.

"Our previous research showed that making multiple lifestyle changes -- eating a healthier diet and increasing physical activity -- for a short-term period of six months led to significant reductions in blood pressure. Now we know that sustaining these lifestyle changes for the longer period of 18 months also leads to substantial blood pressure reductions," Vollmer said. "This is very good news, because the longer people can keep their blood pressure down, the better it is for their heart health. The other good news is that this study shows that people can make and sustain these lifestyle changes over a fairly long time period."

'Dietary Approaches to Stop Hypertension'

The study, funded by the National Heart, Lung and Blood Institute (NHLBI), was conducted at four clinical centers at Duke University; Johns Hopkins University; Louisiana State University; and Kaiser Permanente's Center for Health Research, which also served as the coordinating center for the study.

A total of 810 men and women ages 25 and older with either prehypertension (120-139mmHg/80-89mmHg) or stage 1 hypertension (140-159mmHg/90-95mmHg) but who were not taking medications to control blood pressure were randomly assigned to three groups.

Participants in two of the groups attended 18 counseling sessions during the first six months -- 14 group meetings and 4 individual sessions. During the last 12 months, they attended 12 group meetings and 3 individual sessions. They were prescribed goals for weight loss and physical activity. They were also given sodium and alcohol intake limits.

One of these groups also received guidance on following the DASH diet, an eating plan rich in fruits and vegetables, low-fat dairy products and low in saturated fat, total fat and dietary cholesterol. DASH stands for "Dietary Approaches to Stop Hypertension," a diet that substantially lowered blood pressure in a previous NHLBI-sponsored feeding study. DASH is used as an example of a healthy eating plan by the US Dietary Guidelines for Americans.

A third group served as a control, receiving only two 30-minute sessions of advice to follow standard recommendations for blood pressure control; one at study enrollment and one 6 months later. A third session was offered at the end of the 18-month trial after measurements were completed.

Control Hypertension Without Drugs?

Rates of high blood pressure declined in all three groups, but the reduction was greater in both intervention groups and most striking in the intervention group that included the DASH eating plan. While approximately 37 percent of participants in all three groups had high blood pressure at the study's start, this was reduced to 22 percent in the group following DASH and 24 percent in the intervention group without DASH. By comparison, the rate of hypertension fell to only 32 percent in the control group.

Goals for the intervention groups included a 15-pound weight loss (95 percent of participants were overweight or obese), 3 hours per week of moderate physical activity, daily sodium intakes of no more than 2,300 milligrams (1 tsp salt), and limits of one alcoholic drink per day for women and two per day for men.

Those also following the DASH diet were asked to increase their consumption of fruits and vegetables to 9-12 servings per day, consume 2-3 servings of low-fat dairy products, and keep total fat to no more than 25 percent of total daily calories. To keep track, participants kept food diaries, monitored calories and sodium intakes, and recorded minutes of physical activity.

More than one-third of all participants had high blood pressure at the beginning of the study. Of these, 62 percent in the intervention group with DASH and 60 percent in the intervention group without DASH had their blood pressure under control after 18 months (that is, their blood pressure levels were no longer considered high). Comparatively, only 37 percent of the control group with hypertension at the study's start had their blood pressure under control at the end of the study.

"These rates of hypertension control produced by the two interventions are even better than the 50 percent control rates typically found when single drug therapy is used to control high blood pressure," Vollmer says. "This is also good news for many people with high blood pressure because it means they may be able to control their hypertension without drugs or by reducing the number of drugs they take. However, we strongly advise patients taking hypertension drugs to consult with their physicians before trying to substitute lifestyle changes for their prescribed drugs."