Carotenoid intake from natural sources and head and neck cancer : a systematic review and meta-analysis of epidemiological studies

Because of their role as antioxidants, the intake of carotenoids has been hypothesized to reduce the risk of head and neck cancer (HNC). We conducted a systematic review and meta-analysis of the epidemiological studies to investigate whether the intake of specific carotenoids from dietary sources, as well as combined carotenoids, is associated with the risk ofHNCaccording to cancer subsites. A comprehensive literature search of the Medline and Scopus databases was conducted. Sixteen articles were identified from the literature search, of which 15 were case-control studies and one prospective cohort study. The risk reduction associated with b-carotene equivalents intake was 46% (95% CI, 20%-63%) for cancer of oral cavity and 57% (95% CI, 23%-76%) for laryngeal cancer. Lycopene and b-cryptoxanthin also reduced the risk for laryngeal cancer; the ORs for the highest category compared with the lowest one of carotenoid intake were50%(95% CI, 11%-72%) and 59% (95% CI, 49%-67%), respectively. Lycopene, a-carotene, and b-cryptoxanthin were associated with at least26%reduction in the rate of oral and pharyngeal cancer (95% CI,2%-44%). Our systematic review and meta-analysis on dietary carotenoids intake and HNC showed carotenoids to act protectively against HNC, in relation to most of single nutrients and subsites.