FRIDAY, Sept. 19, 2008 (HealthDay News) -- Too much salt can contribute to resistant high blood pressure despite taking several medications to control it, University of Alabama researchers report.
High blood pressure is called resistant hypertension when blood pressure remains above goal despite their taking three medications to lower it. High blood pressure that is under control, but requires four or more medications to treat it, is also considered resistant to treatment.
"High-salt diet contributes importantly to resistant-to-treatment hypertension and high volume and vascular resistance may contribute to resistant hypertension," said lead researcher Dr. Eduardo Pimenta, now at the Department of Hypertension and Nephrology at the Dante Pazzanese Institute of Cardiology in Sao Paulo, Brazil.
Details of the study were expected to be presented Friday at the American Heart Association's Fall Conference of the Council for High Blood Pressure Research, in Atlanta.
For the study, Pimenta's team randomly assigned 13 patients with resistant high blood pressure, to a high- or low-salt diet. These patients were all taking at least three blood pressure medications.
The researchers found that patients on the low-salt diet saw their systolic blood pressure drop by 22.6 mmHg, and their diastolic blood pressure dropped by 9.2 mmHg, compared with people on high-salt diet.
In addition, body weight, as well as brain natriuretic peptide levels and thoracic fluid content, two measures indicating fluid reduction, also significantly increased among those on the low-salt type compared with those on the high salt, the researchers found.
"Patients with resistant hypertension, in spite of three or more antihypertensive drugs, are specially salt-sensitive," Pimenta said. "The blood pressure reduction achieved with low-salt diet was higher than some antihypertensive drugs."
Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles, agreed that salt could contribute to resistant high blood pressure.
"This small, but interesting, study, shows among patients with medication-resistant hypertension that salt restriction has a substantial impact on lowering blood pressure by reducing intravascular fluid retention and improving vascular function," Fonarow said.
Recent large-scale clinical trials show that blood pressure can be effectively lowered by following the Dietary Approaches to Stop Hypertension (DASH) eating plan and by eating less salt, Fonarow said.
"Excess sodium intake, above 2,300 milligrams daily, should be avoided in all patients with hypertension, and among those patients with medically resistant hypertension, a closely monitored low-salt diet [1,500 milligrams daily] should be considered," Fonarow advised.
For more about high blood pressure and salt, visit the American Heart Association.