Final answer:
Bacterial fermentation of lactose in the colon produces lactic acid, hydrogen, carbon dioxide, methane, and short-chain fatty acids. These products result from the activity of lactic acid bacteria and are responsible for flatus in the colon. Hydrogen production is also used to diagnose lactose intolerance via the hydrogen breath test.
Step-by-step explanation:
The bacterial fermentation of lactose in the colon produces several gases and by-products due to the activity of intestinal bacteria. Bacteria such as Lactobacillus and other lactic acid bacteria (LAB) are involved in the process known as lactic acid fermentation, which primarily yields lactic acid. Additionally, as a consequence of the bacterial breakdown of lactose, gases such as hydrogen, carbon dioxide, and methane are produced. This process also generates short-chain fatty acids that are important for colon health.
In the context of the hydrogen breath test, hydrogen production is a key indicator of lactose intolerance. The produced hydrogen is absorbed into the bloodstream, transported to the lungs, and then exhaled. The presence of hydrogen in exhaled breath suggests that lactose is not digested properly, as it is fermented by bacteria in the colon instead.