Diet and risk of adult glioma in eastern Nebraska, United States

Objective: To investigate potential associations between diet and adult glioma. Methods: We conducted a population-based case-control study of adult glioma in eastern Nebraska. Nutrient and food group intakes were estimated for 236 glioma cases and 449 controls using information obtained from a food-frequency questionnaire. Results: After adjusting for potential confounders, inverse associations with risk of adult glioma were observed for intakes of dark yellow vegetables (highest quartile versus lowest: OR = 0.6, P_trend = 0.03) and beans (OR = 0.4, P_trend = 0.0003), but no associations were seen for dietary sources of preformed nitrosamines or high-nitrate vegetables. Our nutrient analysis revealed significant inverse associations between risk of adult glioma and dietary intake of pro-vitamin A carotenoids (highest quartile versus lowest: OR = 0.5, P_trend = 0.005), α-carotene (OR = 0.5, P_trend = 0.01), β-carotene (OR = 0.5, P_trend = 0.01), dietary fiber (OR = 0.6, P_trend = 0.048) and fiber from beans (OR = 0.5, P_trend = 0.0002). We observed no significant associations with risk of adult glioma for intakes of other nutrients or compounds including nitrate, nitrite, vitamin C, vitamin E, saturated fat, cholesterol, dietary fiber from grain products, or fiber from fruit and vegetables. Conclusion: Our study does not support the N-nitroso compound hypothesis, but suggests potential roles for carotenoids and possibly other phytochemicals in reducing risk of adult glioma.