Doctors know that those who regularly consume garlic have less cardiovascular disease, but until now did not know why. In this lab study, researchers determined for the first time that human red blood cells convert the active sulfur compound in garlic (allicin) into hydrogen sulfide or H(2)S, a sulfur compound that tells the blood vessels to relax (dilate), increasing blood flow. Scientists found that blood vessels also convert allicin to H(2)S and that as H(2)S levels rise, blood vessels dilate proportionately. Doctors suggested that because allicin converts to H(2)S and H(2)S regulates how much blood vessels dilate, nutrition companies could create a standardized garlic supplement to dilate blood vessels. The researchers noted, “Few plants other than garlic contain [these] sulfur compounds, and garlic is the only one of these with a dietary use.”
In a second study, researchers found that polyphenols, the beneficial antioxidants in olive oil, helped reduce risk for blood clots in people with high cholesterol. Twenty-one volunteers with high cholesterol ate two breakfasts containing a low-polyphenol (80 ppm) or high-polyphenol (400 ppm) olive oil on alternate days. Two hours after each meal, researchers measured several blood clotting factors and found that those in the high-polyphenol olive oil group were significantly less likely to form blood clots than were those in the low-polyphenol olive oil group. Researchers concluded that high-quality virgin olive oil—which has more polyphenols than lower-quality olive oil—reduces risk for blood clots in those with high cholesterol.