Vitamin C is water-soluble and the body cannot make it, so it has to come from fruit, vegetables or supplements. You will find regular tablets, slow-release tablets, chewables and effervescent tablets. Effervescent tablets are easy to take but often contain sodium, so check the label if you need to limit salt. Common strengths are 500 mg or 1,000 mg per tablet, already above the daily need of most adults, so there is no reason to take several at once. People with a history of kidney stones should ask a doctor before taking high doses. The list is ranked by the independent usdxu score from real sales and ratings.