What is Vitamin C? Vitamin C remains one of the most widely used supplements across the world. Vitamin C tablets are perfect for complementing a healthy, balanced diet, whilst also supporting immune function. Research also suggests that Vitamin C can help to reduce the duration of illness. Where is Vitamin C found? Common sources of Vitamin C include: Broccoli, strawberries, pineapple & oranges. Vitamin C can also be referred to as: Ascorbic Acid. Why use Vitamin C? Intense training