Smelly garlic: a lung tonic?

Many people suffer from acute pulmonary hypertension, where blood pressure is selectively elevated in the lungs. The potentially lethal condition can make the right side of the heart work too hard and thus lead to heart failure. This particular form of high blood pressure might be prevented by a daily downing of two cloves of fresh garlic or its powdered equivalent, a new study in rats suggests.

Seven years ago, pharmacologist David D. Ku of the University of Alabama in Birmingham reported experiments showing that constituents of some garlic tablets could relax constricted blood vessels,just what is needed to alleviate pulmonary hypertension (http://www.sciencenews.org/pages/ sn_arc98/5_23_98/food.htm). The tablets that were most effective had been prepared from fresh garlic or were labeled as likely to contain allicin. That highly reactive compound, responsible for garlic's characteristic pungent aroma, normally forms only when raw garlic is crushed.

Now, Ku's team has fed pure allicin or over-the-counter garlic supplements, some of which contained allicin, to rats for 3 weeks before administering a drug that causes pulmonary hypertension. Other animals received either no supplement or allicin free garlic before being induced to have this type of hypertension. Only the animals receiving allicin were protected from progressive injury to the walls of blood vessels and high blood pressure in their lungs.

Ku used sophisticated tools to determine how much, if any, allicin a garlic supplement had. Unfortunately, he notes, supplement labels gave no reliable clue of allicin's presence or quantity.--J.R.