Dietary carotenoids, essential fatty acids, and risk of colorectal cancer : a case-control study
aEpidemiology Research Unit, Research Centre, CHUM-Hôtel-Dieu, QC, Montréal, bMcLaughlin Centre for Population Health Risk Assessment, Institute of Population Health, University of Ottawa, Ottawa, ON, Canada
AIM: Some epidemiological studies suggest that consuming fruits and vegetables with a high carotenoid content may protect against colorectal cancer (CRC). The evidence, however, is not completely consistent. In an attempt to resolve some of the outstanding questions, a case-control study of French-Canadian in Montreal, was undertaken to examine the possible association between dietary carotenoids and CRC risk and to investigate whether this association varies with regard to lifestyle factors such as smoking or diet-related fatty acids. METHODS: A total of 402 colorectal cases (200 males and 202 females) and 688 population-based controls matched for age, gender, and place of residence were interviewed. Dietary intake was assessed through a validated food frequency questionnaire. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated in unconditional logistic regression models. RESULTS: After adjustment for important variables such as total energy intake, no association was found between dietary intake of carotenoids and CRC risk. Among those who had never smoked, a significantly reduced risk of CRC was associated with consumption of beta-carotene [OR=0.44; 95%CI(0.21-0.92); P=0.02], while an increased risk was associated with consumption of lutein + zeaxanthin [OR=2.22; 95%CI(1.06-4.63); P=0.05]. Among smokers, an inverse association was found between lycopene and CRC risk [OR=0.63; 95%CI(0.40-0.98); P=0.05]. For women with high intakes of essential fatty acids, inverse associations were found between lutein + zeaxanthin and CRC risk. ORs were 0.46 (P=0.04) for arachidonic acid, OR=0.41 (P=0.03) for eicosapentaenoic acid, and OR=0.36 (P=0.01) for docosahexaenoic acid. CONCLUSION: The results of this study suggest that a diet rich in both green vegetables and fish may be important in the prevention of CRC.
Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Nice, France; February 7 - 10, 2004; in oral session 793 (Dietary influences).