Dietary total antioxidant capacity and odds of lung cancer: a large case-control study

Background& aims: We aimed to study the association between dietary total antioxidant capacity (dTAC) and lung cancer (LC) odds in an Iranian population. Methods: We recruited histopathologically diagnosed LC patients and healthy subjects from 10 provinces of Iran. Trained interviewers conducted face-to-face interviews using a structured questionnaire to collect demographic and other non-dietary information. Dietary habits in the previous year were evaluated using a validated food frequency questionnaire (FFQ). We calculated daily energy and nutrient intakes using the USDA Food Composition Table. DTAC was assessed as ferric reducing antioxidant power (FRAP) and total radical-trapping antioxidant parameters (TRAP) whose scores were calculated using published databases. The odd ratios (OR) of LC and 95% confidence intervals (CI) were estimated using unconditional logistic regression after adjusting for potential confounders. Moreover, we assessed the associations in stratified groups of age, gender, tobacco including waterpipe smoking, and opium use. Results: Six hundered and sixty patients and 3,412 healthy controls were included in our study. Higher FRAP and TRAP scores were associated with a lower odd of LC (FRAP, upper tertile (T3) vs. lower tertile (T1): OR = 0.53, 95% CI: 0.40–0.68; TRAP, T3 vs. T1: OR = 0.44, 95% CI: 0.33–0.57) with a significant dose-response trend for both scores (p < 0.01). The inverse association was seen for both indicators in all histologic types of LC and in all stratified analyses including male/female, tobacco smokers/nonsmokers, opium users/nonusers, water pipe users/nonusers, and subjects under/over 50 years of age. However, Interaction between none of these variables with dTAC scores was significant. Conclusion: Higher dTAC is associated with a lower odd of LC. The strong association in all subgroups highlights the importance of an antioxidant-rich diet intake in all subjects, even in the low-risk group.