The basic upshot is this: taking vitamin C supplements will, in all likelihood, have no effect on your health. Since it's a water-soluble vitamin, any excess you take in will simply be excreted out in your pee. The greatest risk is that you'll get diarrhea or some other vague gastrointestinal problems (assuming that you don't have hereditary hemochromatosis, or iron overload, in which case it can actually cause long-term damage to your internal tissues). Taking vitamin C every day probably won't hurt you, but you almost certainly don't need it. It's not difficult to get enough in your diet without popping pills. You can find it in oranges, garlic, strawberries, chili peppers, kiwi, beef liver, oysters, guava, broccoli, parsley, onion, peach, apples, pears, carrots, bananas, avocados, plums, and a whole host of other foods that you never realized had vitamin C in them or possibly have never heard of (see: camu camu, seabuckthorn, and cloudberries).