Green tea contains compounds known as polyphenols, including phytochemicals that have antioxidant, antibacterial, antiviral,  and health enhancing properties. Epidemiological studies have shown that green tea protects against cancer, lowers cholesterol levels, and reduces the clotting tendency of the blood.  Because green tea boosts immune function and acts as an antiviral and anti-inflammatory agent, it may help prevent cancer. In one study, it was shown to prevent the symptoms associated with colds and  flu, and even reduce the number of these illnesses. It also shows promise as a weight-loss aid that can promote burning of fat and help to regulate blood sugar levels and insulin levels.