a nutrient that the body needs in small amounts to function and stay healthy. vitamin c helps fight infections, heal wounds, and keep tissues healthy. it is an antioxidant that helps prevent cell damage caused by free radicals (highly reactive chemicals). vitamin c is found in all fruits and vegetables, especially citrus fruits, strawberries, cantaloupe, green peppers, tomatoes, broccoli, leafy greens, and potatoes. it is water-soluble (can dissolve in water) and must be taken in every day. vitamin c is being studied in the prevention and treatment of some types of cancer. also called ascorbic acid.