Gout is a type of arthritis that occurs when excess uric acid—a natural compound in the body—builds up in the blood. In a 20-year study of about 47,000 men, those who consumed over 1,500 mg of vitamin C per day from all sources were nearly half as likely to have gout as were men who got less than 250 mg per day.
In gout, excess uric acid forms sharp, needle-like crystalline deposits in the joints, causing inflammation and pain. Doctors believe vitamin C may help the kidneys excrete excess uric acid and may keep excess uric acid from forming.
Archives of Internal Medicine; 2009, Vol. 169, No. 5, 502-7.