Garlic has always been known for its good health effects inspite of its bad smell that it generates in your mouth!!
It is used extensively in India with vegatables. Generally, we use raw garlic (uncrushed) and make our tadka(Garlic tomato paste). There is nothing bad in using it raw but research in food cooking has proved that Garlic retains its medicinal properties if you chop or crush Garlic before cooking.
The research was targeted to examine how the heat of cooking affects the chemical compounds associated with garlic’s beneficial health effects.
The researchers have found that even a few minutes of cooking reduces levels of those compounds. The reduction is steepest in whole garlic, and less pronounced in garlic that has been crushed before cooking. Crushing or chopping garlic releases an enzyme, alliinase, that catalyzes the formation of allicin, which then breaks down to form a variety of healthful organosulfur compounds.
Hence, allowing crushed garlic to stand for 10 minutes before cooking enhances formation of those compounds before heat inactivates alliinase.
The studies have also proved that using fresh Garlic instead of the processed one helps the patients of Heart disease. Processed garlic obviously contains preservatives which may reduce the kind of benefits you can derive from fresh produce.