Taking garlic and vitamin C supplements together may reduce blood pressure, says a new study published in the journal Nutrition Research (2007, vol. 27, no. 2).

Scientists from New York's Pharmaceutical Research Institute at Albany College of Pharmacy recruited six people with marginally high blood pressure (140/90 mmHg). With one-week breaks between each course, subjects completed ten-day doses of vitamin C alone (2 grams per day), then garlic capsules alone (2.5 grams per day of freeze-dried bulb powder), and finally, a combination of the two.

Taking vitamin C by itself did not affect the subjects' blood pressure. Garlic alone reduced systolic (peak) blood pressure, but not diastolic pressure (when the heart is resting). But together, vitamin C and garlic reduced systolic levels to between 110 and 120 and diastolic to 75 to 80.

Blood pressure dropped, researchers theorized, because cells lining the walls of the blood vessels were producing more nitric oxide, a compound that helps to regulate blood pressure and immunity, as well as many other bodily functions. Taking garlic supplements alone caused a twofold increase in cellular nitric oxide production, they said. But combining garlic and vitamin C resulted in a threefold increase.

An estimated 72 million Americans older than 20 (1 in 3 adults) have high blood pressure, the number-one changeable risk factor for stroke.