Chromosome translocation frequency and intakes of B vitamins, meat, and grain products in airline pilots.
Proceedings of the American Association for Cancer Research (AACR) 101st Annual Meeting, April 17-21, 2010, Washington, DC. Abstract 2812. Philadelphia, PA: American Association for Cancer Research, 2010 Apr; 51:1
B vitamins such as folate and vitamins B2, B6, and B12 are essential for the maintenance of DNA integrity. Deficiency in these B vitamins can result in DNA strand breaks which, if unrepaired, can lead to the formation of chromosome aberrations (CA). Niacin also contributes to chromosome stability due to several important roles, including DNA repair and regulation of cell division and apoptosis. Animal and in vitro studies suggest that these B vitamins may protect against chromosome damage induced by ionizing radiation (IR), but data from IR-exposed human populations are limited. Airline pilots are exposed to cosmic IR, an efficient inducer of CA which have been shown to be associated with increased cancer risk. We examined the association between the frequency of translocations (stable form of CA) and intakes of these B vitamins and their food sources in 82 male airline pilots. All subjects completed a self-administered questionnaire with information on occupational history and lifestyle factors. Dietary vitamin B intakes were estimated using a validated semiquantitative food-frequency questionnaire and were energy-adjusted. Translocations were scored in an average of 1039 cell equivalents (CE) per subject using fluorescence in situ hybridization with whole chromosome paints, and expressed per 100 CE. Negative binomial regression was used to estimate rate ratios (RR) and 95% confidence intervals (CI), adjusted for age, flight experience in years, self-reported personal diagnostic X-ray procedures, military service, and lifestyle factors. We observed a significant inverse association between the frequency of translocations and intake of niacin from food: adjusted RR (95% CI) for subjects in the highest compared with lowest tertile was 0.58 (0.40, 0.83). Translocation frequency was not associated with total niacin intake from food and supplements, nor was it associated with intakes of folate, or vitamin B2, B6, or B12 either from food or from food and supplements. These results remained unchanged after further adjustment for the combined intakes of vitamins C and E, ß-carotene, ß-cryptoxanthin, and lutein-zeaxanthin from food (previously shown to be significantly and inversely associated with translocation frequency), or multivitamin supplement use. Additionally, the adjusted RR (95% CI) for = median compared with < median intake of whole grains (median 7.5 servings/week) was 0.69 (0.50, 0.96) and of red and processed meat (median 14.5 servings/week) was 1.56 (1.13, 2.16). Significant inverse associations were also previously observed for high intakes of vitamin C-rich fruit and vegetables, citrus fruit, and green leafy vegetables which are food sources of B vitamins, especially folate. Our data suggest that a high intake of niacin from food or a diet high in whole grains as well as fruits and vegetables but low in red and processed meat may protect against IR-induced chromosome damage.
Proceedings of the American Association for Cancer Research (AACR) 101st Annual Meeting, April 17-21, 2010, Washington, DC