Vitamin C health benefits include the production of the tissue that holds muscles and bones together, promotes wound healing; supports immune function and keeps gums healthy and since vitamin C is a powerful antioxidant it may reduce the risk of some cancers and prevent signs of aging. It also is helps your body absorb the iron from plant foods. 
It is found to be helpful in the prevention of cataracts, macular degeneration, heart disease, stroke, cancer, and colds and improves wound healing and response to stress.
Severe vitamin C deficiency symptoms include scurvy (bleeding, bruising, hair and tooth loss, joint pain, and swelling), which is rare today. Marginal deficiencies are common among the elderly, alcoholics, and those with cancer, chronic illness, or stress. Vitamin C deficiency symptoms include fatigue, easy bruising, poor wound healing and appetite, anemia, and sore joints.
Drugs that deplete vitamin C include oral contraceptives, aspirin, corticosteroids, and furosemide. Large doses of vitamin C (greater than 1,000 mg/day) may reduce the effect of warfarin (blood-thinning drug).
Natural and synthetic forms are chemically identical and have the same effects on the body. Vitamin C from calcium ascorbate is buffered and therefore less acidic and less likely to cause upset stomach. Side effects may include upset stomach, diarrhea, kidney stones (in those at risk), and excess iron absorption.
It is easy to get the recommended amount of vitamin C from foods including: citrus fruit, tomatoes, red peppers, broccoli, strawberries, and potatoes.