Dietary Antioxidants and Melanoma: Evidence from Cohort and Intervention Studies

Melanoma is the most serious form of skin cancer affecting mostly people of Caucasian origin and is associated with high exposure to solar ultraviolet (UV) radiation. Antioxidants in the diet are thought to prevent UV-induced DNA damage and oxidative stress and laboratory-based studies have shown that high antioxidant intakes inhibit melanoma development. Corresponding epidemiological evidence is inconsistent, however. We therefore reviewed results from prospective observational studies and randomized controlled trials (RCTs) to clarify whether consumption of antioxidant vitamin C, E (tocopherol), and A (retinol), carotenoids and selenium, as food, supplements, or both, or high fruit and vegetable intake, reduce the incidence of cutaneous melanoma. A total of 9 studies (2 cohort, 1 nested case-control, 6 RCTs) were included. Neither antioxidant nutrients, individually or combined, nor fruit and vegetable intake showed any strong and significant associations with melanoma, though the number of relevant studies was limited and several had methodological shortcomings. In particular, melanoma was not a primary disease outcome in any of the RCTs and therefore, none adequately accounted for potential confounding by sun exposure. In conclusion, available evidence is currently inadequate to assess possible beneficial effects of antioxidant intake on melanoma risk.