Which gas pair is produced by colonic bacteria from remaining oligosaccharides and contributes to bloating?

• A. CO2 and CH4
• B. H2 and O2
• C. CO2 and H2
• D. O2 and CO2

Answer: (D)

Fermentation of remaining oligosaccharides by colonic bacteria occurs in an anaerobic environment, so no oxygen is produced. The typical gaseous end products are carbon dioxide and hydrogen, with methane produced by some microbes in certain individuals. This gas buildup in the colon contributes to bloating, making carbon dioxide and hydrogen the most consistent pair to associate with this process.