A study suggested that eating two cloves of raw garlic a day could protect against a severe form of pulmonary hypertension.

The study was performed on rats. A small dose of monocrotalline was used on rats to induce vasoconstriction of the pulmonary arteries. Within three weeks, the control group of rats developed chronic pulmonary hypertension with pulmonary arterial pressure markedly increased while the group pf rats that received small doses of allicin, an active metabolite from garlic, in their diet did not develop the disease.

The study also found that it was allicin that plays the role in the prevention of the severe pulmonary hypertension. Garlic if heated or with allicin stripped does not have the protective effect.

The researchers demonstrated that this protective effect was achieved through vasorelaxation or reduction in tension of the blood vessel walls.

Garlic has been known for long to be medicinally beneficial to the human health. It may help lower blood pressure, decrease ischemic injury, reduce blood cholesterol, inhibit platelet functions and increase thrombolysis or destruction of a thrombus.

Allicin was proved in a separate study by the same group "to protect coronary vascular function and lessen the severity of right heart hypertrophy, two of the serious byproducts of chronic pulmonary hypertension", according to the news released by Federation of American Societies for Experimental Biology.

Although the study was conducted on rats, it's expected that garlic has the same effect on humans. The effective amount used on rats is equivalent to about two cloves of garlic a day for humans.

The study was conducted by Dr. David D. Ku and colleagues from University of Alabama at Birmingham. Results of the study were presented on April 2 at the Experimental Biology 2005 meeting in San Diego.