What causes people to pass gas?

When there is too much air in your digestive system, there are two ways to get rid of it. It can exit from the top, through your mouth, in the form of a burp. Or it can exit from the bottom, through your anus, in the form of passed gas, better known as a fart. Some of the gas in your digestive system comes from the air you swallow when you eat, while some of it is a natural by-product of food digestion in your large intestine. When your intestine encounters foods that are difficult to digest—including greasy or high-fat foods—it produces more gas than with foods that are digested easily. This gas travels through your intestine to your rectum and eventually passes out through your anus. While some may not like to admit it, everyone passes gas several times a day.