Garlic supplements have strong antioxidant properties, which are beneficial in preventing cells from becoming weak or susceptible to disease. It also is used to reduce cholesterol, lower blood pressure, and improve blood flow, all important factors in reducing the advance of cardiovascular disease. Garlic has proved beneficial against the common cold. Although comprehensive studies are still underway, promising research suggests that garlic supplements strengthen the immune system in ways that reduce cancer risks and combat existing cancers.