The gut is a large organ, which is continuously remodeling itself in order to maintain its structure and function. One of the most important functions of the gut is to protect the body from ingested bacteria and dietary anti-nutritional factors (such as fiber) by secreting large amounts of mucus. Mucus is primarily composed of mucin proteins, which are continuously synthesized and secreted. In order to produce this mucus, the gut needs a large amount of specific nutrients such as the essential amino acid threonine. Because mucins are resistant to digestion, mucin proteins and the associated threonine are lost from the body. When the body is challenged by bacteria or dietary fiber, the gut reacts by increasing the production and release of mucus, which means even more threonine is needed to maintain an appropriate intestinal defense. Because the body cannot make threonine, more dietary threonine is required to meet the increased demands by the gut. Does this diversion of limited dietary threonine to the gut reduce the amount of threonine reaching the rest of the body for growth?
This research will show that a bacterial toxin and fiber challenge will increase mucus secretion in the gut, which in turn will require more threonine. In order to develop dietary recommendations for this increased mucus secretion we will develop a method to determine accurately the gut's actual requirement for threonine and how this changes with a gut challenge. Finally, this research will determine whether the whole body supply of threonine is diverted to the gut for mucus synthesis in the event of a gut challenge. Overall, this research will describe how the gut responds to a challenge and how the body re-organizes its nutrient demands in order to accommodate the gut's increased requirements. Not only is this information critical in the animal industries of Canada where low-grade gut diseases and high fiber diets are common, but such information is also essential to design effective therapeutic diets for human patients with gut diseases or infections.