Diet Potentiates the UV-Carcinogenic Response to β-Carotene

Abstract

The role of β-carotene as an anticancer agent has been questioned as a result of clinical trials in which the incidence of nonmelanoma skin cancer was unchanged in patients receiving a β-carotene supplement and in β-carotene-supplemented smokers who suffered a significant increase in lung cancer occurrence. In laboratory studies, β-carotene-supplemented semidefined diets, in contrast to earlier studies employing commercial closed-formula diets, not only failed to provide a protective effect to ultraviolet (UV) carcinogenesis but resulted in significant exacerbation. A rationale for this distinct carcinogenic response to β-carotene rests with the stability of the carotenoid radical cation, believed to be dependent on the presence of other antioxidants for rapid repair, and suggests that response to β-carotene depends on the presence and interaction with other dietary factors. Here, we report that diet potentiates β-carotene-mediated exacerbation of UV carcinogenesis. Although the dietary factor(s) responsible for this effect is unidentified, these studies underscore the potential risk of β-carotene supplementation in free-living populations where dietary status is widely varied.