Vitamin C (ascorbic acid) is a water-soluble vitamin that supports normal growth and development. Vitamin C also helps your body absorb iron. Because your body doesn't produce or store vitamin C, it's important to include vitamin C in your diet. For most people, a small glass of orange juice and a cup of strawberries, a medium orange, or a serving of broccoli provide enough vitamin C for the day. Any extra vitamin C will simply be flushed out of your body in your urine. Still, it's possible to have too much of a good thing. Although too much vitamin C from your diet is unlikely to harm you, megadoses of vitamin C supplements can cause nausea, diarrhea, kidney stones and inflammation of the stomach lining (gastritis). Rarely, too much vitamin C can cause faintness, dizziness and fatigue.