I talk about gas so much, you would think I would have the answer down pat. Well, I don't. But to give you a simplified answer, there are chemical reactions going on in the body which give off gas. Like some bicarbonates with acid in your stomach which give off carbon dioxide.Secondly, air which you inhale goes into the blood and from there some components can diffuse back into the digestive system.And thirdly, the most important one is bacteria which feed off the carbohydrates and produce gas in the process. I think kmottus describes it as them giving off millions of tiny little farts which all add up to the ones we experience
