In the study, which will be published in the Aug. 12 issue of the Journal of Agricultural and Food Chemistry, boffins also challenged the widespread belief that most of garlic's benefits are due to its rich array of antioxidants.
Instead, garlic's heart-healthy effects seem to result mainly from hydrogen sulfide, a chemical signaling substance that forms after garlic is cut or crushed and relaxes blood vessels when eaten.
In the study, Dipak K. Das and colleagues point out that raw, crushed garlic generates hydrogen sulfide through a chemical reaction. Although best known as the stuff that gives rotten eggs their distinctive odor, hydrogen sulfide also acts as a chemical messenger in the body, relaxing blood vessels and allowing more blood to pass through.
rocessed and cooked garlic, however, loses its ability to generate hydrogen sulfide.
To reach the conclusion, scientists gave freshly crushed garlic and processed garlic to two groups of lab rats, and then studied how well the animals' hearts recovered from simulated heart attacks.
"Both crushed and processed garlic reduced damage from lack of oxygen, but the fresh garlic group had a significantly greater effect on restoring good blood flow in the aorta and increased pressure in the left ventricle of the heart," Das said.