Science Questions

Why do people fart? Sally in Luton

There are a number of reasons why we have gas in our guts. Some of it's just air that we swallow, which contains nitrogen, carbon dioxide and oxygen. The rest of it is made when undigested food and a sugar called lactose passes through into our large bowel, and bacteria start eating the sugar. The bacteria produce quite a lot of smelly gases, especially if the food has quite a lot of sulphur in it. This would include food like cauliflower, eggs and meat. Beans are particularly fart-o-genic, and although they don't make bad smells, they do make you produce quite a lot of gas. This is because beans contain quite a lot of sugars that humans can't digest, but bacteria love them! When you get worm infections, it actually increases your level of flatulence. This is being published in a scientific journal very soon.

November 2005