(NaturalNews) You probably know that getting enough fiber in your diet can keep constipation at bay and it can lower high cholesterol levels, too. Now Australian researchers have found another reason why the indigestible part of plant-based foods, known as roughage, is good for you -- it plays an important role in keeping your immune system healthy and in preventing specific diseases.When fiber moves through the digestive tract it remains mostly unchanged, working as a type of internal broom. Then, in the colon, bacteria interact with roughage. Fermentation takes place, producing compounds called(SCFAs) which are known to help soothe ulcerative colitis, an inflammatory gut condition. Probiotics and prebiotics, beneficial bacteria found in kefir, yogurt and nutritional supplements, affect the healthy balance of gut bacteria and have been documented to help the symptoms of two other inflammatory diseases, asthma and rheumatoid arthritis.But what is the connection between fiber, "good" intestinal bacteria and the healing of disorders marked by inflammation? In a study just published in the science journal, Sydney-based scientists say they've found the answer to that question. They've discovered a mechanism that explains how a plant-based diet rich in fiber works with beneficial gut bacteria and the immune system to promote health and potentially prevent a host of diseases.Kendle Maslowski, a PhD student, and Professor Charles Mackay from the Garvan Institute of Medical Research, working in collaboration with the Co-operative Research Center for Asthma and Airways, have demonstrated that a molecule dubbed GPR43 expressed by immune cells and previously shown to bind SCFAs reduces inflammation. They found that mice lacking the GPR43 gene have increased, unresolved inflammation in their bodies because their immune cells can't bind to and use SCFAs.So how does this information translate into helping human health?Maslowski explained in a statement to the press. "Changing diets are changing the kinds of gut bacteria we have, as well as their by-products, particularly short-chain fatty acids. If we have low amounts of dietary fiber, then we're going to have low levels of short chain fatty acids, which we have demonstrated are very important in the immune systems of mice."Professor Mackay pointed out in the press statement that the notion what you eat might have profound effects on immune responses and inflammatory diseases has never been taken seriously enough. "We believe that changes in diet , associated with western lifestyles, contribute to the increasing incidences of asthma, Type 1 diabetes and other autoimmune diseases. Now we have a new molecular mechanism that might explain how diet is affecting our immune systems," he stated.The scientists conclude that their current research provides compelling reasons to eat a diet rich in unprocessed whole foods such as fresh fruits, vegetables, grains, nuts and seeds. "The role of nutrition and gut intestinal bacteria in immune responses is an exciting new topic in immunology, and recent findings including our own open up new possibilities to explore causes as well as new treatments for inflammatory diseases such as asthma," said Professor Mackay.