In terms of scientific research however, garlic has long been known for it’s anti-oxidant properties. That is its ability to provide protection against free radical damage in the body. In a study1, a team of researchers from the Cardiovascular Research Centre at the University of Connecticut School of Medicine have found that garlic may be more valuable than simply for it’s anti-oxidant benefits.
As it transpires, freshly crushed garlic, rather than processed or dry garlic, protects the heart. Crushed garlic generates a chemical reaction that produces hydrogen sulphide. You might know hydrogen sulphide as that odiferous smell that comes off rotten eggs. Yes it’s the same stuff. But biologically speaking, hydrogen sulphide is a chemical messenger that relaxes the blood vessels. This in turn allows more blood to pass through. The difference is that processed and cooked garlic actually lose their ability to generate hydrogen sulphide.
“Freshly crushed garlic generates hydrogen sulphide, a gas that is also generated from rotten egg,” says Professor Dipak K. Das of the study. “Although this gas in excess may become poisonous, in small quantities it functions as an intracellular signalling compound and can protect the heart.”
In the study1 scientists tested two groups of rats. One group they gave freshly crushed garlic. The other, processed garlic. They then studied how well the rodent’s hearts recovered from simulated heart attacks.
Whilst garlic in all of its forms was noted to reduce damage from the deprivation of oxygen to the heart, it was the fresh garlic group that showed the most impact in restoring blood flow to the heart.
“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.
Essentially this is good news and bad news. The good news of course is that if you eat a clove of garlic a day you’ll start to experience the health benefits of garlic. The bad news is that you’re eating raw, crushed garlic. Which means whilst your heart may be thanking you, no one on the train in the morning will.
 Freshly Crushed Garlic is a Superior Cardioprotective Agent than Processed Garlic. Subhendu Mukherjee, Istvan Lekli, Shyamal Goswami†, and Dipak K. Das Cardiovascular Research Center, University of Connecticut School of Medicine, Farmington, Connecticut 06030-1110 Agric. Food Chem., 2009, 57 (15), pp 7137–7144 DOI: 10.1021/jf901301w