Antioxidant supplements contribute towards the protection of cells from oxidative stress. Antioxidants fight free radicals which steal electrons from healthy cells in the body creating damage. Although a certain degree of free radicals are required by the body, when their levels get to high, oxidative stress occurs causing damage to DNA and contributing to illness. In fruits and vegetables, colour indicates antioxidant presence. The body produces its own antioxidants from nutrients obtained from food, (for example selenium is used to make an antioxidant enzyme), or the nutrients can be used directly as antioxidants, such as vitamins C and E.