Many ancient cultures believed that garlic had magical healing qualities , and it was used for health purposes thousands of years ago in Egypt, Greece , and India. Modern scientists have found that eating garlic really does have several valuable health benefits . "Allicin , the same substance that gives garlic its odor , kills bacteria , viruses , and funguses . Cloves of garlic also contain selenium , a nutrient that helps prevent the oxidation in cells which can lead to cancer . Garlic has also been shown to lower blood pressure . It can help reduce the chance of heart attack or stroke by thinning the blood , which prevents clots from forming . addition , garlic can clear the sinuses and relieve cold symptoms like commercial decongestants , it thins mucus so sinuses and lungs can flush themselves out more easily .