According to the U.S. National, Lung, and Blood Institute, one in three United States adults have high blood pressure, reading over 140/90 millimeters of mercury. Hypertension or high blood pressure a preventable and treatable risk factor for heart attack and stroke but approximately 25 percent of adults do not know they have it, according to a new study published in the January issue of Circulation: Cardiovascular and Quality Outcomes.

Many who do know about their condition are not likely to have it under control, says lead researcher Dr. Uchechukwu Sampson, a cardiologist at Vanderbilt University Medical School in Nashville. "Despite all the progress we have made in having available treatment options, more than half of the people we studied still have uncontrolled high blood pressure," Sampson said.

In the study, the researchers evaluated how prevalent hypertension was in 69,000 participants in the southeastern U.S., an area known for high rates of cardiovascular disease. 57 percent self-reported them having high blood pressure. Blacks were more likely to be affected more than whites and extremely obese individuals were more likely to high blood pressure than those who were not obese, according to the researchers

Dr. Daniel Kolansky, an Interventional cardiologist and associate professor of medicine at the University of Pennsylvania's Perelman School of Medicine told HealthDay  News, "This study points out that high blood pressure is still a huge problem in this country".

Sampson noted that more information is needed to understand why the number of untreated hypertension patients are so high.