Objective: Numerous epidemiological studies show an increased prevalence of
metabolic diseases related to oxidation stress causing cell damage. Antioxidant supplementation is
therefore useful to protect against the oxidative stress mediated disease development and has
become an increasingly popular practice. In this review, a selection of clinical and in vitro studies
on vitamin C and E supplementation and the evaluation of their beneficial or negative effects have
Results: Clinical studies and supplementation trials show a correlation between antioxidants and
metabolic improvement in different diseases such as cancer, cardiovascular disease, diabetes,
obesity. Vitamin C (ascorbic acid) and E (α-tocopherol) appear to be among the most commonly
used antioxidants. However, taking antioxidant supplements in high doses can be harmful. In some
studies, little supportive evidence has been provided on substantial protection against chronic
diseases by antioxidants. In addition, previous studies have revealed negative effects of antioxidant
supplements such as pro-oxidant activities in particular conditions including their dosage and the
body oxidant/ antioxidant status.
Conclusion: Antioxidant supplements should be used with caution.