Dietary exposure to nitrite and nitrosamines and risk of nasopharyngeal carcinoma in Taiwan

Previous studies of nasopharyngeal carcinoma (NPC) have found elevated risk s with higher consumption of salted fish and preserved foods, particularly during childhood. These foods can contain high levels of nitrosamines; howe ver, most studies have not estimated exposure to nitrosamines directly. We conducted a case-control study in Taiwan to evaluate dietary intakes and NP C risk. A total of 375 cases (99% response rate) and 327 controls (88% resp onse rate) were interviewed about their diet as an adult and at age In usin g a food-frequency questionnaire. We interviewed mothers of participants ab out their child's diet at age 10, age 3 and during weaning and the mother's diet while she was breastfeeding. Mothers of 96 cases and 120 controls wer e interviewed. Nitrosamine and nitrite levels were assigned to 66 foods bas ed on published values, Intake of nitrosamines and nitrite as an adult was not associated with risk of NPC. High intakes of nitrosamines and nitrite d uring childhood and weaning were associated with increased risks of NPC for foods other than soy products. Adjusted odds ratios for the highest quarti le were 2.2 [95% confidence interval (CI) 0.8-5.6] for age in, 2.6 (95% CI 1.0-7.0) for age 3 and 3.9 (95% CI 1.4-10.4) for weaning diet. Intakes of n itrite and nitrosamines from soybean products during childhood and weaning were inversely associated with risk. Soybeans contain known inhibitors of n itrosation, and thus may explain the inverse association we observed. Our r esults suggest that nitrosamine and nitrite intake during childhood may pla y a role in the development of NPC.