食物中总亚硝基化合物及其相关危险因素研究

目的　探索南方食管癌现场中亚硝基化合物综合危险因素。方法　在南方食管癌高发区南澳县和低发区陆丰县各随机选择12 0名35～6 4岁健康男性居民,收集2 4小时膳食和3天12小时夜尿。分别为空白尿样、5 0 0mg脯氨酸+2 0 0mg维生素C(VC)负荷尿样和5 0 0mg脯氨酸负荷尿样。测定总亚硝基化合物(TNOC)、挥发性亚硝胺、亚硝基氨基酸(NAAs)和还原型VC。用非条件logistic模型分析各类亚硝胺摄入水平和排泄水平、NAAs内源性合成能力、VC的营养状况及其对内源性合成的阻断能力等综合因素与食管癌死亡率的关系。结果　非条件logistic回归分析筛选出两个食管癌亚硝胺危险因素—膳食TNOC含量(OR为9 6. 13,95 %CI 1 92 .1～4 8 .115 )和服VC后尿NAAs浓度(OR为1 137,95 %CI为1 0. 0 1～1 2 .98)。结论　膳食TNOC高含量和VC对NOC内源性合成的低阻断能力是南方食管癌高死亡率的两个重要危险因素。

Study on N-nitroso compound in food and its relevant risk factors for esophageal cancer

Objective To study multiple risk factors of N-nitroso compounds (NOC) in high- and low-risk areas for esophageal cancer in southern China. Method The samples of 24-hr diets and 12-hr overnight urine were collected from 120 male healthy subjects (35-64 years old) selected by a 3-stage random cluster sample procedure in each of the high-risk area (Nanao County) and low-risk area (Lufeng County) for esophageal cancer. The urinary samples were respectively collected from undosed subjects, subjects ingested 500 mg L-proline (together with 200 mg ascorbic acid ) and subjects ingested 500 mg proline. The levels of total NOC (TNOC), N-nitrosamino acids (NAAs), volatile N-nitroso compounds and reductive ascorbic acid (VC) in the samples were measured. By unconditional logistic stepwise regression model, we analyzed the association between the multiple factors of NOC and esophageal cancer mortality. The factors included the intake and excretion levels of various kinds of NOC, the ability of NAAs endogenous formation and its inhibition by VC, and nutrition status of VC in the body. Results The results of unconditional logistic stepwise regression showed that risk factors entered the model were diet TNOC content (OR 9.613, 95%CI 1.921-48.115)and urinary NAAs level after ingested VC (OR 1.137, 95%CI 1.001-1.298). Conclusion The higher level of diet TNOC and the lower inhibition ability of NOC endogenous formation by VC were important risk factors on NOC etiology of esophageal cancer in southern China.