Final answer:
Lack of GLUT5 in the small intestine leads to increased fermentation of fructose in the colon, potentially causing bloating and digestive distress.
Step-by-step explanation:
When there is little or no GLUT5 present in the small intestine enterocytes, fructose cannot be efficiently absorbed. Consequently, fructose passes into the colon where it is subject to fermentation by the gut microbiota. Unlike carbohydrates absorbed in the small intestine, this unabsorbed fructose is fermented, producing gas and potentially causing symptoms like bloating and discomfort in a manner similar to what can occur with lactose when lactase is deficient (leading to lactose intolerance). In such scenarios, the absence of enough GLUT5 can lead to increased fermentation of fructose, and in the absence of the right digestive enzymes, this can augment symptoms associated with digestive distress, such as bloating.
\When there is little or no GLUT5 present in the small intestine enterocytes, fructose cannot be efficiently absorbed and transported into the epithelial cells. Instead, it reaches the colon undigested. In the colon, fructose is fermented by bacteria through the process of saccharolytic fermentation, resulting in the production of hydrogen, carbon dioxide, and methane gases. This fermentation process can lead to increased fructose fermentation, bloating, and the production of flatus (gas) in the colon.