Vitamin C promotes antioxidant protection and is one of the leading vitamins for immune support. At the 60th Anniversary Meeting of the American Academy of Allergy, Asthma, and Immunology (AAAAI), it was reported that 12 healthy subjects who took one gram of vitamin C a day for two weeks showed a boosted immune system response during that time. What's more, when they looked at responses in four of the patients, they found that in two of them, the response to vitamin C took place within five hours. According to the researchers this might mean that taking a vitamin C tablet at the first sign of a cold could achieve an effect quickly enough to ward off that cold.