An excess of bacteria in the gut can change the way the liver processes fat and could lead to the development of metabolic syndrome, according to health researchers. Metabolic syndrome is a group of conditions including obesity, type 2 diabetes, high blood pressure, high blood sugar and excess body fat around the waist. People experiencing three or more of these conditions are considered to have metabolic syndrome and are vulnerable to liver and heart diseases. Approximately 20 to 25 percent of adult Americans have the syndrome, according to the American Heart Association. Research supported by the National Institutes of Health has recommended that Americans add more fiber to their diets because higher fiber diets have been found to improve many aspects of health. However in a certain segment of the population, this advice could be doing more harm than good. “It is a common misconception that plant–derived dietary fiber contains zero calories,” said Matam Vijay–Kumar, assistant professor of nutritional sciences and medicine at Penn State. While it’s true that neither people nor mice can digest plant–derived fiber, their gut bacteria can readily ferment the fibers and then release them as energy–rich short–chain fatty acids, such as acetic acid. Once they reach the liver, these compounds convert into lipids and add to fat deposits that could potentially lead to the development of metabolic syndrome, especially in people and mice lacking toll–like receptor 5 (TLR5). TLR5 is a receptor for bacterial flagellin and is part of the innate immune system that maintains gut–bacteria homeostasis, keeping gut bacteria from over–proliferating. Approximately 10 percent of the human population has a genetic mutation in TLR5, resulting in a complete lack of its function, according to Vijay–Kumar. These individuals have a weakened immune system that may increase the risk of developing metabolic syndrome.
Pennsylvania State University Health and Medicine News, 11/03/2015