FRIDAY, Sept. 28 (HealthDay News) -- An Italian study has identified overweight as a direct cause of high blood pressure. And it also showed that up to half of overweight people can bring down blood pressure to healthy levels by weight reduction.

But the weight loss has to be achieved before the borderline to outright obesity is crossed, said Dr. Roberto Fogari, professor of medicine at the University of Pavia. He was to present the study findings Friday at the annual meeting of the American Heart Association's Council for High Blood Pressure Research, in Tucson, Ariz.

It's important that the study linked overweight to high blood pressure, which usually is described as "essential," a medical term meaning that the cause is unknown, Fogari said.

"The study suggests that, in many cases, hypertension [high blood pressure] is not essential," he said. "It is secondary to overweight. So, in the first stages of overweight, if we can induce people to reduce overweight, they can also avoid being treated for hypertension."

The study included 210 men and women whose body mass index [a ratio of weight to height] was between 25 and 29.9, indicating overweight but just short of the 30 mark of obesity. Their systolic blood pressure was between 140 and 159, and their diastolic pressure was between 90 and 99, indicating moderately high blood pressure.

An individualized low-calorie diet was designed for each study participant. Some also were prescribed orlistat, a drug that prevents fat from being metabolized.

After six months, 53 percent of the men and 49 percent of the women in the study achieved normal body weight, and a 5 percent reduction in blood pressure.

"The other 50 percent of those in the study already had abnormal changes in the vascular tree [blood vessel system], so that hypertension was no longer reversible by losing weight," Fogari said.

The implication for practicing physicians who see moderately overweight people with high blood pressure is that their first goal should be weight reduction, he said.

"Only after six months of trying to reduce the patient's weight can a decision be made about drug treatment," Fogari said.

Dr. Daniel W. Jones, dean of the University of Mississippi School of Medicine, and a spokesman for the American Heart Association, said the study finding "is not new news, but it is important news."

There have been a number of previous studies showing that weight loss can reduce blood pressure, Jones said. "But this is an increasingly important problem in societies around the world," he said. "Once you gain weight, you find it difficult to lose weight, which is why we focus so much on preventing obesity these days."

As for drug treatment of high blood pressure, about half of California adults diagnosed with hypertension do not take medication for it, another report presented at the same meeting found.

The study of 11,467 persons given a diagnosis of hypertension found that 49.4 percent were not taking drugs to reduce their blood pressure, said the report by researchers at the California Department of Public Health's Heart Disease and Stroke Prevention Program.

There were some bright spots in the picture. Compliance was more than five times higher for those who had seen a doctor in the past year than for those who had not. And the compliance rate was twice as high for persons with health insurance than the uninsured.

More information

For more on high blood pressure and what to do about it, turn to the American Heart Association.

SOURCES: Roberto Fogari, M.D., professor of medicine, University of Pavia, Italy; Daniel W. Jones, M.D., head, University of Mississippi School of Medicine, Jackson; Sept. 28, 2007, fall meeting, American Heart Association Council for High Blood Pressure Research, Tucson, Ariz.

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