Harvard Health Tips
Vitamin C supplements
Many people take vitamin C supplements in unnecessarily high doses to prevent or treat various conditions for which its effectiveness is unproved, from preventing cardiovascular disease and osteoarthritis, to staving off sunburn, to improving the appearance of wrinkles. To date, scientific studies don't support this practice. For adults, the tolerable upper intake level (UL) ? the highest daily intake likely to pose no risks ? is 2,000 mg per day.