FRUCTOSE IN DENOVO LIPOGENESIS IN HUMANS

果糖是一种天然存在于水果和蔬菜中的糖，并且越来越多地作为加工食品和饮料中的甜味剂。它对肥胖或糖尿病患者有潜在的益处;然而，有证据表明它也可能导致血浆甘油三酯、总胆固醇和LDL胆固醇水平升高。这些参数的增加与冠状动脉疾病的风险增加有关，特别是在已经处于这种疾病高风险的人群中。本研究的目的是确定膳食果糖对正常体重、肥胖和II型糖尿病人群中甘油三酯和胆固醇从头合成的影响。氘（一种稳定同位素）的掺入速率将用于确定氘标记掺入新形成的胆固醇和甘油三酯的速率。将在2个饮食阶段收集数据。每组将入组12例受试者。受试者将进食等热量流质饮食（55%碳水化合物、15%蛋白质、30%脂肪）5天。在一个测量期间，30%的热量将由果糖提供，在另一个测量期间，30%的热量将由麦芽糊精提供。受试者将饮用0.7 g D2 O/kg总身体水分。在接下来的36小时内，每餐前6小时采集一次血样。几周后将重复这项研究，届时将消耗剩余形式的糖。将通过薄层色谱法分离血浆胆固醇和甘油三酯，并通过同位素比质谱法测定掺入的氘量。氘掺入血浆甘油三酯和胆固醇的速率将用于计算从头脂肪生成的速率。

Fructose is a form of sugar occurring naturally in fruits and vegetables, and increasingly, as a sweetener in processed foods and beverages. It has potential benefits to obese or diabetic individuals; however, evidence exists that it may also lead to high levels of plasma triglyceride, total cholesterol, and LDL cholesterol. Increases in these parameters are associated with increased risk of coronary artery disease, especially in populations already at high risk for this disease. The purpose of this investigation is to determine the effect of dietary fructose on de novo synthesis of triglyceride and cholesterol in normal weight, obese, and Type ll diabetic populations. The rate of incorporation of deuterium, a stable isotope, will be used determine the rate of incorporation of a deuterium label into newly formed cholesterol and triglyceride. Data will be collected in 2 dietary periods. Twelve subjects will be enrolled in each group. Subjects will consume an isocaloric liquid diet (55% carbohydrate, 15% protein, 30% fat) for 5 days. During one measurement period, 30% of calories will be supplied by fructose, in the other, 30% of calories will be supplied by maltodextrine. Subjects will drink 0.7 g D2O/kg total body water. Over the next 36 hours, blood samples will be drawn every 6 hours prior to a meal. The study will be repeated several weeks later, at which time the remaining form of sugar will be consumed. Plasma cholesterol and triglyceride will be isolated by thin layer chromatography and the amount of deuterium incorporated will be determined by isotope ratio mass spectrometry. The rate of deuterium incorporation into plasma triglyceride and cholesterol will be used to calculate the rate of de novo lipogenesis.