For vitamin C capsules, choose a listing that explicitly identifies vitamin C and its capsule format. Ester-C with citrus bioflavonoids is one clearly named example to inspect. Compare the vitamin C amount per full serving, capsule count and additional ingredients. A capsule containing another vitamin is not automatically interchangeable, and a combination formula should be checked separately from a product with a different ingredient list.View Ester-C with Citrus Bioflavonoids – Non-Acidic Form of Vitamin C – 500 MG (120 Capsules).