Evaluation of Biological Relevance of Choline Intake

描述（由申请人提供）： 胆碱是人体必需的营养素，参与多种代谢途径，包括甲基转移。动物研究表明，胆碱缺乏症是在没有其他致癌物质的情况下足以发展为肝细胞癌的条件。不含胆碱和低蛋氨酸的甲基缺乏饮食促进动物化学诱导的致癌作用。叶酸和甲硫氨酸摄入量低的甲基缺乏饮食与人类几种器官的癌症有关。然而，由于缺乏饮食胆碱摄入量的食物组成数据，对胆碱在人类中的作用的理解受到阻碍。最近，我们通过食物频率问卷获得了食物的胆碱成分数据。在我们使用人群的摄入量数据之前，我们建议检查一般人群摄入量范围内胆碱摄入量变化的生物相关性。使用来自Frachial Offspring研究的数据，我们将研究胆碱摄入量和血浆同型半胱氨酸水平之间的关系，同型半胱氨酸是甲基代谢的中间产物，也是身体甲基可用性的指标。我们将描述胆碱摄入量与其他饮食和生活方式因素之间的关系。我们还将在护士健康研究中检查胆碱摄入量与结直肠腺瘤风险的关系，这是一项针对女性的大型前瞻性研究。这些数据将提供证据，证明人群中胆碱摄入量是否存在可测量的和生理上重要的变化。拟议拨款的结果将加强对胆碱摄入量在人类中作用的理解，并为未来关于胆碱摄入量和整体甲基缺乏饮食和癌症的研究奠定基础。

DESCRIPTION (provided by applicant): Choline is an essential nutrient for human and is involved in many metabolic pathways, including methyl-group transfer. Animal studies have demonstrated choline deficiency as a condition sufficient for the development of hepatocellular carcinoma in the absence of other carcinogens. A methyl-group-deficient diet with no choline and low methionine promotes chemically induced carcinogenesis in animals. A methyl-group-deficient diet with low folate and methionine intake has been related to cancers of several organs in humans. However, understanding the role of choline in humans has been hampered by lack of food composition data for dietary choline intake. Recently, we obtained choline composition data for foods measured by our food frequency questionnaire. Before we use the intake data in populations, we propose to examine the biological relevance of variation in choline intake over the range of intake in a general population. Using data from the Framingham Offspring Study, we will examine the relation between choline intake and plasma levels of homocysteine, an intermediate product in methyl-group metabolism and an indicator of the body's methyl-group availability. We will characterize the relationship between choline intake and other dietary and life-style factors. We will also examine choline intake in relation to colorectal adenoma risk in the Nurses' Health Study, a large prospective study of women. These data will provide evidence whether measurable and physiologically important variation in choline intake exists within populations. The results from the proposed grant will enhance understanding of the role of choline intake in humans and lay the groundwork for future studies on choline intake and overall methyl-group-deficient diet and cancer.