What do they do? Garlic has antibacterial, antiviral, and antifungal activity. It may work against some intestinal parasites. Garlic appears to have roughly 1% the strength of penicillin against certain types of bacteria.
Many publications have shown that garlic supports the cardiovascular system by lowering cholesterol and triglyceride levels in the blood, inhibit platelet stickiness (aggregation), and increase fibrinolysis—which results in a slowing of blood coagulation. It is mildly antihypertensive and has antioxidant activity. Three reviews of double blind studies in humans have found that garlic can lower blood cholesterol levels in adults by approximately 10%. Garlic has been shown to be as effective as the drug bezafibrate in lowering cholesterol levels. However, a recent placebo-controlled study found no effect for garlic on lowering cholesterol. Several double blind studies also suggest it can prevent atherosclerosis. Garlic is also helpful for persons with intermittent claudication (cramping in the lower legs secondary to poor blood flow), according to one controlled study.
Eating garlic regularly reduces the risk of esophageal, stomach, and colon cancer. This is partly due to garlic’s ability to reduce the formation of carcinogenic compounds. Animal and test tube studies also show that garlic and its sulfur compounds inhibit the growth of different types of cancer—especially breast and skin tumors.
Parsley leaf or root has een used to relieve irritation of the urinary tract and to aid in passing kidney stones. Although there is no evidence that parsley is helpful for these conditions, two of its constituents, apiol and myristicin, are believed to be diuretics; because diuretics would increase the flow of urine, this might help the body to wash out bacteria as well as stones.