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Iron, zinc, and calcium are major micronutrients in diet sources and supplements. Iron, zinc, and calcium are all involved in the metabolism of reactive oxygen species and other free radicals, and may compete with each other for similar binding sites. Dietary intake of these micronutrients has been associated with altered risks of colorectal, breast, and prostate cancers. In this hospital based case-control study with 472 Caucasian incident early stage lung cancer patients and 1125 healthy unrelated spouses and friends controls, we analyzed the associations between dietary iron, zinc, and calcium intake and the risk of lung cancer. Dietary intake was assessed at the time of recruitment (1992 to 2000) with the use of a 126-item semiquantitative food-frequency questionnaire. The results were analyzed using multiple logistic regression models, adjusting for smoking history and other potential risk factors including total caloric intake. The adjusted odds ratios of dietary iron, zinc, and calcium were 1.55 (95% confidence interval, 1.05-2.30; Ptrend<0.01), 0.73 (95% CI, 0.50-1.07; Ptrend=0.07), and 1.69 (95% CI, 1.16-2.45; Ptrend=0.03), respectively, for highest quartile vs. lowest quartile of each micronutrient. Stronger associations between micronutrients and lung cancer risk were found when these micronutrient were analyzed in the same model. Similar associations with lung cancer risk were also found for total iron, zinc, and calcium intake that included supplements. By different food sources, the increased risk effect of dietary iron was from non-heme iron vs. heme iron sources (red meat, poultry, and seafood), with the adjusted odds ratios of non-heme iron and heme iron of 1.56 (95% CI, 1.05-2.32; Ptrend=0.02) and 0.46 (95% CI, 0.30-0.71; Ptrend<0.01), respectively, for highest quartile vs. lowest quartile. In conclusion, this is the first study demonstrating the statistically significant associations between dietary micronutrients and the risk of lung cancer. Our results suggest that dietary iron and calcium intake may be associated with higher risk of lung cancer, while dietary zinc intake may be associated with lower risk of lung cancer. Supported by NIH grants CA74386, CA90578, ES/CA 06409, and ES00002

[Proc Amer Assoc Cancer Res, Volume 46, 2005]