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（GI）和血糖负荷（GL）值测定的个体内重现性（在同一个体内重复测量）和个体间变异性（个体间）。实现该目标的具体目的是评估生物学特征-体重指数（BMI）、年龄和性别不同的志愿者中GI值测定的再现性和可变性;评估大量营养素的量和组合以及纤维对GI和GL值测定的可变性的影响;评估先前膳食大量营养素组成对GI和GL值测定的影响;以及评估先前膳食大量营养素组成对GI和GL值测定的影响。（“第二餐”效应）对GI值测定的影响;并将这些数据与在干预期之前和期间监测的慢性疾病风险因素相关联。这些目的将通过评估在选择代表BMI范围的志愿者中，相对于葡萄糖，白色面包（通常用作参考食物）的重复GI值测定的个体内再现性和个体间变异性来实现（18.5-24.9，25-29.9，30岁）和年龄（18-49.9，50-85岁），并基于性别，并将这些数据与身体成分和胰岛素敏感性（I期）相关联。然后，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）以及最终“第二餐”效应（第三阶段）可能引入的变异性相关的问题。在每组食物激发（随机顺序的葡萄糖和测试食物）之前，将基于空腹HbA 1c、果糖胺、脂质和脂蛋白、胰岛素、葡萄糖和C-反应蛋白对志愿者进行表征。在5小时激发期间（在0、15、30、45、60和此后每30分钟取样），将监测志愿者的血糖、胰岛素、甘油三酯、总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。GI和GL的概念都是公共领域的，并且已经建议将这些概念并入美国联邦饮食指南（美国饮食指南和饮食参考摄入量[DRI]），其被制定为促进健康和降低慢性疾病风险。本建议涉及一些未充分研究的领域，这些领域的额外信息将有助于确定是否应按照建议使用GI和GL对食品进行分类，并为一般人群制定膳食指南。

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.