An ingredient in garlic appears to prevent a potentially deadly type of high blood pressure affecting the lungs, at least in rats, according to new research presented Saturday.

The garlic ingredient, called allicin, seems to ward off pulmonary hypertension, or high blood pressure in the arteries that bring blood to the lungs. In humans, pulmonary hypertension can lead to potentially fatal complications in the heart and blood vessels.

“Garlic is very effective against pulmonary hypertension,” researcher Dr. David D. Ku of the University of Alabama at Birmingham told Reuters Health.

Ku added that humans would need to eat two cloves of garlic every day to equal the rats’ dose of allicin. He also cautioned that these findings are still very preliminary, and a lot more research is needed before doctors can recommend garlic in people who run the risk of developing pulmonary hypertension.

To put rats at risk of pulmonary hypertension, Ku and his team gave them a drug that triggers a constriction of the arteries feeding the lungs. Some of the rats received a garlic extract that contained allicin, and some of the rats ate boiled garlic, which contains no allicin.

By three weeks, rats that did not get any garlic had developed pulmonary hypertension, while the rats given allicin largely did not. Rats that ate allicin-free garlic developed pulmonary hypertension, as well, confirming that allicin is the key ingredient.

In an interview, Ku explained that allicin likely prevents pulmonary hypertension by causing the constricted blood vessels to relax, and by preventing damage to the blood vessels.

Interestingly, Ku said he and his colleagues experimented with allicin in other forms of hypertension and found it was largely ineffective, suggesting that the lung’s blood vessels are “uniquely responsive to allicin.”

Ku and his colleagues presented their findings during the meeting of the American Society for Pharmacology and Experimental Therapeutics in San Diego, California.