Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, MD 20850, USA.
Cancer Prevention Fellowship Program, Division of Cancer Prevention, National Cancer Institute, Rockville, MD 20850, USA.
Int J Environ Res Public Health. 2021 Jun 25;18(13):6822. doi: 10.3390/ijerph18136822.
Nitrate and nitrite are precursors in the endogenous formation of N-nitroso compounds (NOC) which are potent animal carcinogens for the organs of the digestive system. We evaluated dietary intakes of nitrate and nitrite, as well as nitrate ingestion from drinking water (public drinking water supplies (PWS)), in relation to the incidence (1986-2014) of cancers of the esophagus (n = 36), stomach (n = 84), small intestine (n = 32), liver (n = 31), gallbladder (n = 66), and bile duct (n = 58) in the Iowa Women's Health Study (42,000 women aged from 50 to 75 in 1986). Dietary nitrate and nitrite were estimated using a food frequency questionnaire and a database of nitrate and nitrite levels in foods. Historical nitrate measurements from PWS were linked to the enrollment address by duration. We used Cox regression to compute hazard ratios (HR) and 95% confidence intervals (CI) for exposure quartiles (Q), tertiles (T), or medians, depending on the number of cancer cases. In adjusted models, nitrite intake from processed meats was associated with an increased risk of stomach cancer (HR = 2.2, CI: 1.2-4.3). A high intake of total dietary nitrite was inversely associated with gallbladder cancer (HR = 0.3, CI: 0.1-0.96), driven by an inverse association with plant sources of nitrite (HR = 0.3, CI: 0.1-0.9). Additionally, small intestine cancer was inversely associated with a high intake of animal nitrite (HR = 0.2, CI: 0.1-0.7). There were no other dietary associations. Nitrate concentrations in PWS (average, years ≥ 1/2 the maximum contaminant level) were not associated with cancer incidence. Our findings for stomach cancer are consistent with prior dietary studies, and we are the first to evaluate nitrate and nitrite ingestion for certain gastrointestinal cancers.
硝酸盐和亚硝酸盐是内源性形成 N-亚硝基化合物 (NOC) 的前体，NOC 是消化系统器官的强力动物致癌物。我们评估了硝酸盐和亚硝酸盐的饮食摄入量，以及饮用水（公共饮用水供应 (PWS)）中的硝酸盐摄入与食管癌（n = 36）、胃癌（n = 84）、小肠癌（n = 32）、肝癌（n = 31）、胆囊癌（n = 66）和胆管癌（n = 58）发病率（1986-2014 年）的关系，研究对象为爱荷华州妇女健康研究中的 42000 名年龄在 50 至 75 岁之间的女性（1986 年）。饮食中的硝酸盐和亚硝酸盐是通过食物频率问卷和食物中硝酸盐和亚硝酸盐水平的数据库来估计的。PWS 的历史硝酸盐测量值通过持续时间与入组地址相关联。我们使用 Cox 回归计算暴露四分位数 (Q)、三分位 (T) 或中位数的危险比 (HR) 和 95%置信区间 (CI)，具体取决于癌症病例数。在调整后的模型中，来自加工肉类的亚硝酸盐摄入与胃癌风险增加相关（HR = 2.2，CI：1.2-4.3）。总膳食亚硝酸盐摄入量高与胆囊癌呈负相关（HR = 0.3，CI：0.1-0.96），这主要是由于植物来源的亚硝酸盐呈负相关（HR = 0.3，CI：0.1-0.9）。此外，小肠癌与动物亚硝酸盐摄入量高呈负相关（HR = 0.2，CI：0.1-0.7）。没有其他饮食相关性。PWS 中的硝酸盐浓度（平均值，年限≥最大污染物水平的 1/2）与癌症发病率无关。我们关于胃癌的发现与之前的饮食研究一致，并且我们是第一个评估硝酸盐和亚硝酸盐摄入与某些胃肠道癌症的关系的人。
