Yang C S, Sun Y H, Yang Q P, Miller K W, Li G Y, Zheng S F, Ershow A G, Li J Y, Blot W J
Natl Cancer Inst Monogr. 1985 Dec;69:23-7.
Plasma levels of nutrients in 196 individuals were assayed as part of a study of the feasibility of a nutrition intervention trial in Linxian, a county in North Central China with exceptionally high rates of esophageal cancer. High-performance liquid chromatography analyses of samples collected in April 1983 showed low (relative to United States standards) base-line levels for retinol, alpha-tocopherol, and beta- and alpha-carotene. Repeat sampling in August 1983 revealed significantly increased plasma levels of retinol and alpha-tocopherol among those who had in the interim received daily supplementation with multivitamin pills containing the Recommended Dietary Allowance levels of those nutrients but not among those without supplementation. Levels of carotenes, which were not included in the pills, tended to increase regardless of supplementation, consistent with seasonal variations in availability of carotenoid-containing foods. Atomic absorption spectrophotometry analyses showed essentially normal levels of copper and zinc in plasma. Neither was affected by vitamin supplementation (the pills did not contain minerals) nor seasonal variation. The data are generally consistent with prior biochemical surveys in indicating marginal or low status of several nutrients in Linxian and in showing that supplementation with vitamins can effectively raise blood nutrient levels.
作为在中国中北部食管癌发病率极高的林县进行营养干预试验可行性研究的一部分，对196人的血浆营养成分水平进行了测定。1983年4月采集的样本经高效液相色谱分析显示，视黄醇、α-生育酚、β-胡萝卜素和α-胡萝卜素的基线水平较低（相对于美国标准）。1983年8月的重复采样显示，在此期间每日补充含有推荐膳食营养素摄入量水平的多种维生素片的人群中，视黄醇和α-生育酚的血浆水平显著升高，而未补充的人群中则没有升高。片剂中未包含的胡萝卜素水平，无论是否补充，都有升高趋势，这与含类胡萝卜素食物供应的季节性变化一致。原子吸收分光光度法分析显示血浆中铜和锌的水平基本正常。两者均不受维生素补充（片剂不含矿物质）或季节变化的影响。这些数据总体上与之前的生化调查一致，表明林县几种营养素的状况处于边缘或较低水平，并表明补充维生素可有效提高血液中的营养素水平。
