2010 Grant Award - Daniel D. Gallaher, Ph.D.
Reduction in Adiposity and Change in Fuel Utilization by Viscous Dietary Fiber in Diet-induced Obesity in Rats
The prevalence of obesity has reached alarming levels. The connection between excess adiposity and chronic diseases is becoming clearer, as it is now understood that adipose tissue is a major endocrine organ, which modulates insulin resistance and energy metabolism. Obesity is associated with chronic low-grade inflammation, the predominant source being adipose tissue, which plays a fundamental role in insulin resistance. It is desirable to identify food components that may reduce adiposity. Viscous dietary fibers are highly bioactive categories of dietary fiber. We have conducted animal studies showing that viscous dietary fibers reduce adiposity, independent of body weight changes. We hypothesize that viscous dietary fiber will also decrease the inflammation of obesity and increase fatty acid oxidation. We will investigate chronic consumption of viscous dietary fiber in rats fed an obesity-inducing diet, which leads to both obesity and insulin resistance, on measures of adiposity, insulin resistance, inflammation, gene expression related to glucose and fatty acid metabolism, and fuel utilization, The viscous dietary fiber to be used is a purified material, hydroxypropyl methylcellulose, as this avoids the confounding effects of other bioactive compounds present in food sources of viscous fibers. The studies described in this proposal will confirm this effect on adiposity and greatly extend it, by examining the effect of viscous polysaccharides on adipose metabolism, fatty acid oxidation, inflammation, and adipose gene expression. If successful, this project may provide a dietary alternative to pharmacological approaches to reduction in body fat. This project represents a collaboration between investigators of several different areas. Dr. Gallaher's area of research has focused on dietary influences on cholesterol metabolism and colon cancer. Thus, research in obesity represents a new area of research for him. Dr. Chen has focused on adipose metabolism, particularly inflammation and insulin resistance, but not obesity reduction per se. Dr. Kotz area of expertise is in neural regulation of food intake. The outcomes of this study will further establish the effectiveness of viscous polysaccharides on adiposity as well as greatly expand our knowledge of the relationship between adiposity, inflammation, and adipokine secretion. This information will be useful in furthering our understanding of how changes in viscous components of the diet affect adiposity and will set the stage for human studies of the effects of these types of dietary fiber on adiposity.