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.
