The Association between Dietary Total Antioxidant Capacity and Glioma in Adults

We assessed the relation between dietary total antioxidant capacity (TAC) and risk of glioma among Iranian adults. Design: A hospital-based case-control study. Setting: This case-control investigation was done in 2011. Usual dietary intakes of participants during the preceding year were examined using a food frequency questionnaire. Data on dietary TAC from foods was gathered from published databases that provided the antioxidant capacity for each food item, measured by ferric reducing antioxidant power. Participants: Cases were individuals with pathologically confirmed glioma that were diagnosed during the last month (n = 128). Controls were individuals, aged between 20 and 75 years, who were hospitalized or were outpatients referred to other wards of the same hospitals (n = 256). Results: Compared with participants in the lowest quartile, those in the highest quartile of dietary TAC had a lower odds of glioma (OR: 0.28, 95%CI: 0.15-0.45). This association was strengthened when potential confounders were taken into account (OR: 0.13; 95%CI: 0.05-0.35). Such inverse association was also seen for men (OR: 0.05, 95%CI: 0.01-0.19), but not for women. Furthermore, significant inverse associations were seen between dietary intakes of vitamin C (OR for Q₄ vs. Q₁: 0.14, 95%CI: 0.05-0.36; P-trend < 0.01), vitamin B6 (OR for Q₄ vs. Q₁: 0.35, 95%CI: 0.13-0.97; P-trend = 0.02) and β-carotene (OR for Q₃ vs. Q₁: 0.43, 95%CI: 0.19-0.98; P-trend = 0.57) and glioma, after controlling for potential covariates. Conclusions: We found that dietary TAC as well as dietary intake of vitamin C, vitamin B6, and β-carotene was inversely associated with odds of glioma in adults.