Study Finds Few Remedies to Curb Mild Hypertension : Health: Dieting and lower salt intake help. But other non-drug methods, including stress reduction, do little.

Tens of millions of Americans with borderline hypertension could cut their blood pressure by losing weight and avoiding salt, but stress reduction and other dietary changes promoted for that purpose will have little effect, a new study has found.

The findings emerged from the first phase of a decade-long federal project exploring the possibility of preventing high blood pressure, a condition that afflicts about 63 million Americans and kills nearly 32,000 a year.

“This is one of the first steps that will lead us toward the goal of a national policy for prevention of hypertension,” said Dr. Paul K. Whelton, a co-author of the study published today in the Journal of the American Medical Assn.

Blood pressure is the force of blood through the arteries. A reading consists of a high figure, the systolic pressure, and a lower figure, the diastolic. A healthy young adult has an average reading of about 110/75 millimeters of mercury (mm Hg), which may rise to 130/90 at the age of 60.

High blood pressure is defined as systolic pressure of at least 140 mm Hg and diastolic pressure of at least 90. But people with borderline-high diastolic levels in the 80s--as many as 80 million Americans, according to Whelton--face some increased risk of complications.

Until recently, patients with mild high blood pressure were commonly put on drugs. But improved understanding of their side effects has prompted physicians to place greater emphasis on non-drug approaches such as weight loss.

“People work very hard not to go on medication,” said Dr. Richard Johnson, associate chief of the division of family medicine at the UCLA School of Medicine, who said physicians encourage weight reduction, salt restriction and stopping smoking and drinking.

The new study, conducted at 11 medical and health centers nationwide, examined the value of seven promising forms of non-drug treatment--weight reduction, salt restriction, stress management and the use of calcium, magnesium, potassium and fish oil as dietary supplements.

Although exercise was a part of the weight reduction regimen, the researchers did not address the effects of exercise by itself.

The survey studied 2,032 men and women ages 30 to 54. All had diastolic blood pressure levels of 80 to 89--levels that would be considered in the “high normal” range, perhaps necessitating regular monitoring. Although systolic and diastolic readings are significant, diastolic pressure is often emphasized because it is less likely to fluctuate.

The participants were divided into groups of several hundred and assigned to one of the seven lifestyle and dietary approaches. They were followed for six to 18 months and their blood pressure levels were tracked.

Those in the weight-loss group, who had cut calories and walked for 45 minutes four times a week, experienced a 2.3 mm Hg average drop in their diastolic blood pressure and 2.9 mm Hg drop in their systolic pressure, the researchers found.

Those in the salt reduction group experienced a 0.9 mm Hg drop in their diastolic pressure and a 1.7 mm Hg drop in their systolic. But neither the people in the stress reduction group nor those taking the nutritional supplements experienced any significant change.

“Certainly there have been individuals who have reported notable success with stress management,” Whelton said. “But our findings are more consistent with a growing pattern (of research findings) that . . . there is no effect.”

Dr. Thomas G. Pickering, a professor of medicine at the cardiovascular center at New York Hospital-Cornell Medical College, said there may be subgroups of patients who benefit from the approaches that the study found to have failed.

Furthermore, Pickering said, nutritional supplements may have other benefits in preventing heart disease and strokes. As for the success of weight reduction and salt restriction, he noted that genetic factors in hypertension may necessitate drug treatment nevertheless.

“The problem with things like weight reduction is you can do it for about six months, but after that, most studies show people tend to creep up again,” Pickering said.

The second phase of the study, already under way, will measure the effectiveness of weight reduction and salt restriction in not merely lowering blood pressure but in actually preventing hypertension in the longer run.

“The real public-policy implications will derive from the data in Phase 2,” said Dr. Charles Hennekens, a professor of medicine at Brigham and Women’s Hospital in Boston and chairman of preventive medicine at Harvard Medical School.

“We know that lowering mild to moderate blood pressure will cut strokes,” said Hennekens, who is coordinating the federal study. “If we can prevent that condition from developing in the first place, that would be a big step.”

According to Whelton, lowering the average blood pressure in the population by as little as 2 mm Hg would cause a 6% drop in stroke deaths per year and a 4% drop in deaths from coronary heart disease.