When it comes to flatulence, you are what you do and eat, according to Dr Chris Kong, a consultant at the Singapore General Hospital’s Department of Gastronenterology and Hepatology. For instance, gobbling your food or smoking can increase the amount of air you swallow. The air may travel to the large intestine and then be expelled as gas. Certain foods and drinks also generate gas (such as beans – want to know whether green or red beans are better?). These include onions and carbonated drinks as well.
Toot reeks because of three sulphur-containing gases: hydrogen sulphide, methanethiol and dimethyl sulphide. The odours range from the smell of rotten eggs to decomposing vegetables, say US researchers. And here’s another stinker: Women’s gas contains higher concentrations of hydrogen sulphide – meaning, theirs smell worse than men’s.
And on the issue of why someone else’s fart often smells worse than your own, Avery Gilbert, PhD, a scent psychologist, offers this explanation: “Your disgust at the stench has more to do with your brain than with your nose. Someone else’s fart is an in-your-face invasion of personal space. But when you break wind, you know what to expect, so the smell doesn’t trigger feelings of intrusion, and it doesn’t register as offensive.”