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

描述（由申请人提供）：本提案的目的是研究单个食物和食物组合的血糖指数（Gl）和血糖负荷（Gl）值测定的个体内可重复性（在同一个体内重复测量时）和个体间可变性（个体之间）。实现这一目标的具体目的是评估不同生物学特征（身体质量指数（BMI）、年龄和性别）的志愿者Gl值测定的可重复性和可变性；评估常量营养素的量和组合以及纤维对Gl和Gl值测定的变异性的影响；评估前一餐常量营养素组成（“第二餐”效应）对Gl值测定的影响；并将这些数据与干预前和干预期间监测的慢性疾病风险因素联系起来。这些目标将通过评估白面包（通常用作参考食物）相对于葡萄糖的重复Gl值测定的个体内可重复性和个体间可变性来实现，选择代表BMI范围（18.5-24.9,25-29.9，¿30）和年龄（18-49.9,50-85）的志愿者，并根据性别将这些数据与身体成分和胰岛素敏感性联系起来（第一阶段）。随后，这项工作将扩展到解决与常量营养素和纤维组合和负荷差异（第二阶段）以及最后的“第二餐”效应（第三阶段）相关的变异性问题。在每组食物挑战（葡萄糖和测试食物随机排序）之前，志愿者将根据空腹HbA1c进行特征描述；果糖胺;脂质和脂蛋白；胰岛素，葡萄糖和C-反应蛋白。在5小时的挑战中（0、15、30、45、60以及之后每30分钟采样一次），志愿者将被监测血糖、胰岛素、甘油三酯、总脂蛋白胆固醇和高密度脂蛋白胆固醇以及非酯化脂肪酸水平的变化。Gl和Gl的概念都属于公共领域，有人建议将这些概念纳入美国联邦膳食指南（美国膳食指南和膳食参考摄入量[DRI]），以促进健康和降低慢性疾病风险。该提案涉及了一些研究不足的领域，在这些领域中，为了确定是否应该像建议的那样，在为一般人群制定膳食指南时，使用Gl和Gl来对个人食物进行分类，额外的信息将是有用的。

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.