Final answer:
Humans cannot digest some fibers like cellulose because we lack the necessary enzymes, so these fibers are fermented by bacteria in the large intestine, aiding in bowel movements and producing healthful compounds.
Step-by-step explanation:
Complex carbohydrates, specifically certain types of fiber, are broken down in the large intestine because humans lack the enzyme necessary to digest cellulose, which is a major component of dietary fiber. In the large intestine, the intestinal flora—composed of various bacteria—can ferment this indigestible fiber. The fermentation process by these bacteria leads to the production of short-chain fatty acids, which provide numerous health benefits. Insoluble fibers add bulk to the stool and help maintain regular bowel movements, while soluble fibers can regulate blood glucose levels and help lower cholesterol.
Fibers like cellulose add bulk and help ease bowel movements due to their indigestible nature. This is because our enzymes cannot bind to the cellulose due to its structure. The only digestion of such fibers occurs through bacterial fermentation in the large intestine, which results in the creation of flatus but also the generation of beneficial short-chain fatty acids.
Complex carbohydrates, specifically some types of fiber, are broken down in the large intestine because the human digestive system does not produce the enzymes necessary to digest cellulose, a type of fiber found in plants. While most carbohydrates are broken down into simple sugar molecules in the digestive tract, fiber remains undigested and adds bulk to the food, easing bowel movements. Fiber also has other important roles in the body, such as promoting regular bowel movements, regulating blood glucose consumption, and reducing the occurrence of colon cancer.