Evaluation of Glycemic Index to Assess Diet-Associated Chronic Disease Risk

描述(由申请人提供)：本建议的目的是调查个别食物和食物组合的血糖指数(Gl)和血糖负荷值(GL)测定的个体内重复性(重复测量时，在同一个体内)和个体间的变异性(个体间)。实现这一目标的具体目的是评估不同生物特征--体重指数(BMI)、年龄和性别的志愿者Gl值测定的重复性和变异性；评估大量营养素的数量和组合以及纤维对Gl和Gl值测定变异性的影响；评估先前膳食中的常量营养素成分(第二餐效应)对Gl值测定的影响；以及将这些数据与干预前和干预期间监测的慢性病风险因素联系起来。为了实现这些目标，将根据性别，评估被选为代表一系列体重指数(18.5-24.9，25-29.9，？30)和年龄(18-49.9，50-85岁)的志愿者的白面包相对于葡萄糖的重复Gl值测定的个体内重复性和个体间变异性，并将这些数据与身体成分和胰岛素敏感性(第一阶段)联系起来。然后，这项工作将扩展到解决与变化相关的问题，这些问题可能由大量营养素和纤维组合和负荷的差异引起(第二阶段)，最后是“第二餐”效应(第三阶段)。在每组食物挑战(按随机顺序排列的葡萄糖和测试食物[S])之前，志愿者将根据空腹糖化血红蛋白、果糖胺、脂类和脂蛋白、胰岛素、葡萄糖和C反应蛋白进行特征分析。在5小时的挑战中(在0、15、30、45、60以及之后的每30分钟采样)，志愿者将被监测血糖、胰岛素、甘油三酯、总和高密度脂蛋白胆固醇以及未酯化脂肪酸水平的变化。GL和GL的概念都是公共领域的，有人建议将这些概念纳入为促进健康和降低慢性病风险而制定的美国联邦膳食指南(美国膳食指南和膳食参考摄入量[DRI])。这项建议涉及一些研究不足的领域，补充信息将是有用的，以便确定是否应如所建议的那样，使用GL和GL对食品进行个别分类，并在为一般人群制定饮食指南时使用。

DESCRIPTION (provided by applicant): The objective of this proposal is to investigate the intra-individual reproducibility (within the same individual, when repeatedly measured) and inter-individual variability (among individuals) of glycemic index (Gl) and glycemic load (GL) value determinations for individual foods and food combinations. The specific aims to accomplished this objective are to evaluate reproducibility and variability of Gl value determinations in volunteers differing in biologic characteristics - body mass index (BMI), age and gender; assess the effect of macronutrient amounts and combinations, and fiber on variability of Gl and GL value determinations; assess the effect of prior meal macronutrient composition ('second meal' effect) on Gl value determinations; and relate these data to chronic disease risk factors monitored prior to and during the intervention period. These aims will be accomplished by assessing intra-individual reproducibility and inter-individual variability of repeated Gl value determinations for white bread, commonly used as a reference food, relative to glucose, in volunteers selected to represent a range of BMI's (18.5-24.9, 25-29.9, ¿ 30) and ages (18-49.9, 50-85 y), and on the basis of gender, and relate these data to body composition and insulin sensitivity (Phase I). This work will then be extended to address issues related to variability potentially introduced by differences in macronutrient and fiber combinations and loads (Phase II), and finally by 'second meal' effects (Phase III). Prior to each set of food challenges (glucose and test food[s] in random order) volunteers will be characterized on the basis of fasting HbA1c; fructosamine; lipids and lipoproteins; insulin, glucose and C- reactive protein. During the 5-hour challenge (sampling at 0,15, 30, 45, 60, and every 30 minutes thereafter) volunteers will be monitored for changes in blood glucose, insulin, triglycerides, total and high density lipoprotein cholesterol and non-esterified fatty acid levels. The concepts of both Gl and GL are in the public domain and it has been suggested that the concepts be incorporated into U.S. federal dietary guidance (U.S. Dietary Guidelines and Dietary References Intakes [DRI]) formulated to promote health and reduce chronic disease risk. This proposal addresses some of the understudied areas for which additional information would be useful in order to determine whether Gl and GL should be used to classify foods on an individual basis, as has been suggested, and when formulating dietary guidance for the general population.