New research suggests that an overhaul of dietary and fitness habits to help prevent or control high blood pressure is feasible with proper coaching, contrary to the theory that too many changes would be overwhelming and ineffective for most people. The best results in the study were achieved when weight loss, salt restriction and exercise were paired with the DASH (Dietary Approaches to Stop Hypertension) diet, which is rich in fruits, vegetables and low fat dairy products.
The results of the study, conducted at Duke University Medical Center, Johns Hopkins, Pennington Biomedical Research Center, and the Center for Health Research, were published in the April 23, 2003, issue of the Journal of the American Medical Association. The study, called PREMIER, is funded by the National Heart, Lung and Blood Institute.
Current national recommendations for lowering blood pressure include weight loss, reduced sodium intake, increased physical activity, limited alcohol consumption and DASH diet. The DASH diet increases fruit, vegetable and low-fat dairy consumption, while limiting fats, red meat, sweets and beverages containing sugar. No previous study has tested the ability of people to adopt DASH on their own or its effectiveness in the real world. And no previous study has tested all the other recommendations for lowering blood pressure, either with or without DASH, as an "all-in-oneintervention.
The PREMIER trial enrolled 810 generally healthy people with above-optimal blood pressure, including those with stage one hypertension (systolic BP140-159 mmHg and/or diastolic BP 90-95 mmHg None of the participants took medications for hypertension. Those in the "Advice Only" group each met with a registered dietitian at the beginning of the trial to discuss recommendations for weight control, reduced sodium intake, physical activity and the DASH diet for lowering blood pressure plus printed educational materials.
Participants in both the "Established" and "Established Plus DASH"intervention groups set goals to lose 15 pounds within six months, increase physical activity, lower sodium intake and limit alcohol to one or two drinks per day. The Established Plus DASH group also set goals to increase fruit, vegetable and low-fat dairy intake and reduce saturated fat and total fat. The Established group was given no instructions on the DASH diet. During the initial six months of the trial, both groups met frequently to reinforce behaviour modification.
During the first six months of the trial, all participants in both the Established and Established Plus DASH groups significantly lowered their blood pressures in comparison to the Advice Only group. The Established Plus DASH group had the lowest prevalence of hypertension cutting group members risk of developing hypertension by 53 percent compared to the Advice Only group. "At six months, we had 19 participants in the Advice Only group who had to begin anti-hypertensive medication to control their blood pressures, compared to only two in the Established Group and five in the Established Plus DASH group," said Svetkey. "And both behaviour modification groups had a significant number of the participants reach their optimum blood pressure."All groups had an overall reduction in weight. In the Established Plus DASH group, 34.3 percent lost 15 pounds or more, while in the Established group, 28.6 percent lost 15 pounds or more. The Advice Only group had only 6.2 percent lose 15 pounds or more. When participants took a treadmill exercise test, the tests showed fitness increased significantly in both the Established and Established Plus DASH groups.
Those on the DASH diet also benefited from other potential benefits: prevention of osteoporosis from the high calcium content, prevention of some cancers from the high fruit and vegetable content, and the prevention of cardiovascular disease from the low fat content."
Although the results for the Advice Only group were not as striking as the other two, this group did better in losing weight and decreasing sodium intake than expected. Svetkey said this could be because motivated people usually sign on to participate in clinical trials, and may produce better results than could be expected in the average population.
The long-term goal of the study, said Svetkey is to follow all the participants for an additional 12 months (18 months total) to determine whether the participants can stick with the diet and exercise, and monitor blood pressure control. The next phase in this series of research will focus on weight loss specifically on how to help people lose weight and keep the weight off long-term. This new study, which is also funded by the National Institutes of Health, began enrolling participants in May 2003.