Vitamin C, also known as ascorbic acid, is a water-soluble vitamin that is important for many bodily functions, including collagen synthesis, immune system function, and wound healing. Vitamin C is found in many fruits and vegetables, including citrus fruits, berries, kiwi, broccoli, and bell peppers. A deficiency in vitamin C can lead to health problems such as scurvy, weakened immune function, and impaired wound healing.