Grant: Operating Grant

The high rate of obesity in Canada is a major public health concern because obesity increases risk for diseases such as diabetes and heart disease. Research shows that people who eat a high amount of dietary fiber gain less weight and are at lower risk of getting diabetes than those with low fiber diets. This may be because fibers are broken down (fermented) by bacteria in the large intestine (colon) to form gases (the cause of flatulence) and substances known as short chain fatty acids (SCFA). The most abundant SCFA is acetic acid, which is commonly consumed in vinegar. SCFA may be beneficial; our research shows that they influence the secretion of hormones such as glucagon-like peptide 1 (GLP-1), peptide YY (PYY), ghrelin and adiponectin which help control appetite and blood glucose levels. On the other hand, research suggests that obese people have different bacteria in their colons which break down fiber to produce more SCFA than lean people and that this causes weight gain because of the extra energy obtained from the SCFA. However, it is unknown if obese people produce more SCFA or not. The purpose of this research is to see if the types of colonic bacteria, and the absorption, metabolism and metabolic effects of SCFA differ in lean and obese subjects. Using a series of tests in human subjects involving intravenous and rectal infusion of acetate and measuring blood SCFA responses after feeding a fermentable fiber we will determine the rates of production, absorption and metabolism of acetate in lean and obese subjects and in people with different kinds of bacteria in their colons and whether these treatments have different effects on hormones and metabolites which control appetite and blood glucose. This research will help us to understand if and how colonic SCFA are involved in the development of obesity in humans so that treatments can be developed to help correct the problem(s) identified and ultimiately help to prevent or treat obe