Vitamin C is one of nature's most powerful antioxidants, working to protect the body from harmful free radical molecules. It's found in some concentration in fruits and vegetables, however citrus fruits, strawberries, cantaloupe, tomatoes, broccoli, potatoes and leafy greens are the best sources.
As a water-soluble vitamin, vitamin C is not stored in the body and must be regularly replaced through diet or supplementation (the body cannot make it on its own). Deficiency is rare, but smoking, stress and certain illnesses can cause reduced levels. Supplementing with vitamin C may help strengthen the immune system.
One study conducted on Vitamin C at the Methodist Hospital in Brooklyn, New York, found significant reductions in blood levels of histamine after people took 1,000 milligrams of Vitamin C for three consecutive days. An Italian study found that people with hay fever, who had taken 2,000 milligrams of Vitamin C daily, were better able to maintain the volume of air they could exhale. Vitamin C may also help reduce some of the inflammation associated with chronic allergies, according to other studies.