Findings from two National Institutes of Health (NIH)-supported studies show that lifestyle changes, such as modifying one's diet and losing weight, substantially reduce blood pressure in adults and can keep older patients off antihypertensive medication. Findings from the studies are being presented at the American Heart Association scientific sessions in New Orleans, LA.
The "Dietary Approaches to Stop Hypertension" (DASH) Trial was funded by the National Heart, Lung, and Blood Institute (NHLBI) and the National Center for Research Resources, with supplemental support from the NIH Office of Research on Minority Health. The "Trial of Nonpharmacologic Interventions in the Elderly" (TONE) was funded by the National Institute on Aging (NIA), with additional support from the NHLBI.
Dr. Thomas Moore of Brigham and Women's Hospital in Boston, MA, will speak about DASH at the late-breaking clinical trials session at 2:15 p.m. on November 13. Dr. Paul Whelton, director of the Welch Center for Prevention, Epidemiology, and Clinical Research at The Johns Hopkins University School of Hygiene and Public Health and School of Medicine in Baltimore, MD, will present TONE's main results at 4:30 p.m. on November 11. Dr. Shiriki Kumanyika of the University of Illinois at Chicago, will describe the TONE intervention 2:00 p.m. on November 13.
"With 50 million Americans having hypertension and many developing it each year, the findings of these two studies have very important public health implications," said NHLBI Director Dr. Claude Lenfant. "The results show the value of lifestyle changes in preventing and controlling this condition," he added.
The studies' results are:
DASH found that a diet low in fat and high in vegetables, fruits, fiber, and low-fat dairy products significantly and quickly lowers blood pressure. The diet was tested without changes in weight, or sodium or alcohol consumption.
For those with hypertension, the diet produced blood pressure reductions similar to those from drug treatment. The multicenter trial examined the effect on blood pressure of whole dietary patterns, rather than of individual nutrients. According to the DASH investigators, prior clinical trials of individual nutrients (such as calcium or magnesium) had produced only small or inconsistent effects on blood pressure. The investigators felt that the nutrients, often taken as supplements, may cause blood pressure decreases too small to be detected in the trials or that multiple nutrients taken together in entire dietary patterns may be needed to produce a significant reduction.
DASH involved clinical centers at The Johns Hopkins University in Baltimore, MD, the Pennington Biomedical Research Center in Baton Rouge, LA, Brigham and Women's Hospital and Harvard Medical School in Boston, MA, and Duke University Medical Center in Durham, NC. The coordinating center was at the Kaiser Permanente Center for Health Research in Portland, OR.
The study enrolled 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic pressures of 80-95 mm Hg. About half were women and nearly 60 percent were African Americans, who tend to develop hypertension earlier and more often than whites.
For 8 weeks, participants were fed one of three diets: a control diet similar in nutrients to what many Americans consume; a diet high in fruits and vegetables, which results in specific increases in fiber, potassium, and magnesium; and a "combination" diet low in total fat, saturated fat, and cholesterol, but high in fruits, vegetables, and low-fat dairy products, which results in specific increases in fiber, protein, potassium, magnesium, and calcium. All three diets had a similar, moderate salt content.
Overall, the combination diet reduced systolic blood pressure by an average of 5.5 mm Hg and diastolic by an average of 3.0 mm Hg. The fruits and vegetables diet also reduced blood pressures but less--by an average of 2.8/1.1 mm Hg.
For those with hypertension, the combination diet reduced systolic blood pressure by an average of 11.4 mm Hg and diastolic by an average of 5.5 mm Hg. The fruits and vegetables diet reduced blood pressure by 7.2/2.8 mm Hg for hypertensives.
Blood pressure reductions occurred in men and women, and in whites and minorities. Further, the blood pressure reductions happened within 2 weeks after the participants started on the diets.
The DASH investigators believe the combination diet, if added to current lifestyle recommendations, could prevent hypertension and reduce or possibly eliminate the need for medication in those who already have the condition. Current recommendations are to maintain a healthy weight, choose foods lower in salt and sodium, drink alcohol in moderation (for those who drink), and be physically active. The DASH combination diet calls for 9-10 servings/day of fruits and vegetables (about twice that now consumed by American adults), along with nearly 3 servings/day of low-fat dairy products (about double the number Americans now consume).
TONE found that weight loss and reduction of dietary sodium safely reduce the need for antihypertensive medication in older patients, while keeping their blood pressure under control.
"This study provides important news for older Americans, many of whom may be able to reduce their use of antihypertensive medication if they make certain lifestyle changes," said Dr. Richard J. Hodes, director of the NIA. "Patients who are now taking medications for high blood pressure should not discontinue or alter their medications without consulting their physician," Dr. Hodes stressed.
The multicenter, 3-year study involved 975 patients at four medical centers--Johns Hopkins University School of Hygiene and Public Health and School of Medicine in Baltimore, MD, the University of Tennessee in Memphis, the University of Medicine and Dentistry of New Jersey--Robert Wood Johnson School of Medicine in New Brunswick, and the Bowman Gray School of Medicine in Winston-Salem, NC.
The study tested the effects on blood pressure of weight loss and sodium reduction, alone and in combination, in non-overweight and overweight patients, ages 60 to 80, whose blood pressure was being controlled by one medication. Patients were men and women; about a quarter were African American.
The 585 overweight patients were assigned to one of four treatments: weight loss alone, sodium reduction alone, combined weight loss and sodium reduction, or usual care, which involved no lifestyle change. The 390 non-overweight patients were assigned to either the sodium reduction or usual care.
At the outset, patients were taking a single antihypertensive medication to keep their blood pressures below 150/90 mm Hg. About 3 months after patients were assigned to a treatment, an attempt was made to taper and discontinue their antihypertensive medication under close supervision. The antihypertensive medication was restarted if a patient's blood pressure did not stay below 150/90 or a physician determined it was needed.
Patients in the weight reduction groups lost 10 to 12 pounds on average. Average sodium intake was reduced to about 2300 mg a day for non-overweight patients and to about 2900 mg for those who were overweight. These reductions were well maintained during followup. The results showed that sodium reduction and weight loss each decreased patients' need for treatment with antihypertensive medication by about 40 percent. After 30 months of followup, almost 40 percent of the patients assigned to the treatments had their blood pressures under control without an antihypertensive medication. Patients assigned to the combination of sodium reduction and weight loss therapy did especially well at maintaining control of their blood pressures without an antihypertensive medication.
To monitor treatment safety, the study looked at patients' cardiovascular events, such as stroke, heart attack, and angina. Few such events occurred in the groups and there were no significant differences among the therapies.
Dr. Eva Obarzanek, nutritionist, and Dr. Jeffrey Cutler, director of the Clinical Applications and Prevention Program, are the NHLBI project officers for DASH and TONE, respectively. To arrange an interview with them, call the NHLBI Communications Office.
Dr. Andre Premen, director of NIA's Cardiovascular Aging Program, is the NIA Project Officer for TONE. To arrange an interview with him or for more information on hypertension and the elderly, call the NIA Information Office.