Ascorbic Acid is a water-soluble vitamin, which take important role in immune system. Vitamin C can help the immune system against viral and bacterial infections, through support immune and increase the bacterial activity of anti-infection cells. If lack of vitamin C, breeder reaction of lymphocyte, the killing ability of cytotoxic T lymphocyte against tumor cells and tardive hypersensitivity will significantly decrease. Interferon, a immune stimulant that secreted by leucocyte, also increases due to vitamin C strengthen. So vitamin C plays an important role in the human immune system.