Lee Duk-Hee, Jacobs David R
Department of Preventive Medicine, college of Medicine, Kyungpook National University, Daegu, Korea.
Nutr Cancer. 2005;52(2):130-7. doi: 10.1207/s15327914nc5202_3.
Redox-active iron present at physiological levels in the pulmonary epithelial lining fluid may lead to damage of lung tissue under some circumstances. For example, factors that increase potential for oxidative stress, such as higher intake of heme iron or higher intake of vitamin C in the presence of high intake of iron, might increase the risk of lung cancer, whereas higher intake of the antioxidant zinc might decrease that risk. During 16 yr of follow-up, 34,708 postmenopausal women, aged 55-69 yr at baseline who completed a food-frequency questionnaire for the Iowa Women's Health Study, were followed for 700 incident lung cancers. When subjects were stratified by intake of vitamin C supplements, among women who took vitamin C supplements of >500 mg/day, after adjusting for age, total energy intake, cigarette smoking, alcohol consumption, and dietary zinc or dietary heme iron intake, relative risks across categories of dietary heme iron intake were 1.0, 0.85, 0.93, 1.32, 1.70, and 3.77 (P for trend = 0.05; P for interaction = 0.08), whereas corresponding figures for dietary zinc intake were 1.0, 1.15, 0.71, 0.84, 0.61, and 0.11 (P for trend = 0.12; P for interaction = 0.04). The strength of the associations of heme iron and zinc intake with lung cancer appeared to be stronger with increasing levels of vitamin C supplement intake. Our results suggest that high dietary heme iron intake may increase the risk of lung cancer, whereas high dietary zinc may decrease the risk of lung cancer among postmenopausal women who consume high-dose vitamin C supplements. This finding may be of particular importance to smokers, for whom vitamin C supplementation is a common recommendation.
肺上皮衬液中生理水平的氧化还原活性铁在某些情况下可能导致肺组织损伤。例如，增加氧化应激可能性的因素，如血红素铁摄入量较高或在铁摄入量高的情况下维生素C摄入量较高，可能会增加患肺癌的风险，而抗氧化剂锌摄入量较高可能会降低这种风险。在16年的随访中，对34708名绝经后妇女进行了跟踪，这些妇女在基线时年龄为55 - 69岁，她们完成了爱荷华妇女健康研究的食物频率问卷调查，共发现700例肺癌病例。当根据维生素C补充剂的摄入量对受试者进行分层时，在每天服用超过500毫克维生素C补充剂的女性中，在调整了年龄、总能量摄入、吸烟、饮酒以及膳食锌或膳食血红素铁摄入量后，膳食血红素铁摄入量各分类的相对风险分别为1.0、0.85、0.93、1.32、1.70和3.77（趋势P值 = 0.05；交互作用P值 = 0.08），而膳食锌摄入量的相应数字分别为1.0、1.15、0.71、0.84、0.61和0.11（趋势P值 = 0.12；交互作用P值 = 0.04）。血红素铁和锌摄入量与肺癌的关联强度似乎随着维生素C补充剂摄入量的增加而增强。我们的结果表明，高膳食血红素铁摄入量可能会增加绝经后女性患肺癌的风险，而高膳食锌摄入量可能会降低在服用高剂量维生素C补充剂的绝经后女性中患肺癌的风险。这一发现对于吸烟者可能尤为重要，因为补充维生素C是对他们的常见建议。
