Vitamin C crystals polarised light micrograph Vitamin C ascorbic acid is a chemical essential for good health It is required for the production of collagen the main constituent in connective tissue acts as a reducing agent to maintain cellular health and as an antioxidant to help mop up destructive free radicals Vitamin C deficiency leads to scurvy causing bleeding and bruising loose teeth a weakened immune system and anaemia It is fatal if left untreated Most animals can produce their own vitamin C