(NaturalNews) A naturally occurring plant compound found in onions may reduce high blood pressure if consumed regularly, according to a new study conducted by researchers at the University of Utah and published in the Journal of Nutrition.
Researchers studied 22 adults with hypertension and 19 adults with pre-hypertension, giving them each either a placebo or a 730-milligram supplement of quercetin each day. The blood pressure of the patients with hypertension who were given quercetin decreased by approximately 7 mmHg systolic and 5 mmHg diastolic relative to those who had been given the placebo. Among the pre-hypertension patients, neither the placebo nor quercetin-supplemented groups experienced a significant change in blood pressure.
The study was randomized and double-blind, meaning that neither researchers nor patients knew who was receiving a placebo, and that this had been randomly determined.
Hypertension is defined as having a blood pressure higher than 140/90 mmHg. The pre-hypertension patients in the study had an average blood pressure of 137/86 mmHg, while the hypertension patients had an average blood pressure of 148/96 mmHg.
"These data are the first to our knowledge to show that quercetin supplementation reduces blood pressure in hypertensive subjects," the researchers said.
Quercetin is in the family of plant chemicals called flavonols, which are known to have antioxidant properties. In the current study, however, quercetin did not appear to cause any changes to the patients' levels of oxidative stress. In some prior animal studies, such an effect has been observed.
The researchers did not conduct tests to determine how quercetin led to the reduction in blood pressure, but they speculated that the chemical may reduce the body's production of a blood-vessel constricting compound called angiotension II.
High blood pressure is associated with more than 7 million deaths each year, in large part due to its connection with cardiovascular disease. According to the American Heart Association, approximately 34.2 percent of people in the United States suffered from cardiovascular disease in the year 2002.