Regulation of cell growth by carotenoids:benefits and liabilities

There is a growing body of literature on the effects of beta-carotene and other carotenoids in human chronic diseases, including cancer. Although epidemiological studies have shown that a high consumption of fruit and vegetables rich in carotenoids is associated with a low risk for cancer, some human ntervention trials showed an increased risk of lung cancer among smokers and asbestos workers. As a consequence of these contradictory findings, there has been considerable interest in elucidating the effects of carotenoids on cell growth. In this review, we showed that carotenoids are able to modulate molecular pathways involved in cell proliferation, differentiation and apoptosis and that such a modulation induces beneficial or detrimental effects, depending on carotenoid concentration and cell status. We also discussed the possible mechhanisms by which carotenoids may act as anti- or pro-carcinogenic agents.