There are more potential heart-healthy benefits in freshly crushed garlic than in dried garlic and processed garlic pastes and powders. The antioxidant effects found in garlic are more potent with fresh types than the dried ones. The potent heart healthy effect of garlic is as a result of hydrogen sulfide, which is a chemical formed after garlic is cut or crushed. This challenges the widespread belief that garlic benefits come from its rich range of antioxidants.
This hydrogen sulfide is responsible for relaxing blood vessels when garlic is eaten. It is a chemical reaction taking place within the raw, crushed garlic that is responsible for the formation of this hydrogen sulfide. In addition to the best known function of hydrogen sulfide in giving rotten eggs their pungent smell, hydrogen sulfide is also known for many more (great) benefits. It acts as a great chemical messenger in the body as it allows for more passage of blood in the blood vessels by relaxing them, etc.
Processed and cooked garlic however does not have the ability to generate this hydrogen sulfide. This was proved in an experiment performed by giving freshly crushed garlic and processed garlic to 2 different groups of laboratory rats. The hearts of the rat groups given freshly crushed garlic were discovered to recover faster and better from simulated heart attacks. It was however discovered that both the freshly crushed and processed garlic reduced damage from lack of oxygen in both groups. The crushed garlic had a much more significant effect in increasing blood flow in the aorta and increasing pressure in the left ventricle (which is the lower left quadrant/chamber) of the heart.