Flatulence is good, and up to 18 a day is totally normal! From NPR:
We know that air often comes after eating nutrient-packed vegetables, such as cabbage, kale and broccoli. And researchers have found that fiber-rich foods, like beans and lentils, boost the levels of beneficial gut bacteria after only a few days, as we reported in December.
So all this got us wondering: Could passing gas, in some instances, be a sign that our gut microbes are busy keeping us healthy? Absolutely, says Purna Kashyap, a gastroenterologist at the Mayo Clinic in Rochester, Minn. "Eating foods that cause gas is the only way for the microbes in the gut to get nutrients," he says. "If we didn't feed them carbohydrates, it would be harder for them to live in our gut."
And we need to keep these colon-dwelling critters content, Kashyap says. When they gobble up food — and create gas — they also make molecules that boost the immune system, protect the lining of the intestine and prevent infections.
"A healthy individual can have up to 18 flatulences per day and be perfectly normal," he adds.
Gas gets into the digestive tract primarily through two routes: Swallowing air (which we all do when we eat and chew gum) and your microbiome. That's the collection of organisms in the GI tract that scientists and doctors are currently all fired up about. (Check our colleague Rob Stein's recent series on it.) That microbiome includes hundreds of different bacteria. But there are also organisms from another kingdom shacking up with them: the archaea.
All these microbes are gas-making fools. They eat up unused food in your large intestine, like fiber and other carbohydrates we don't digest, and churn out a bunch of gases as waste. But that's not all they make. They also produce a slew of molecules (called short chain fatty acids) that may promote the growth of other beneficial bacteria and archaea.
And the more fiber you feed these friendly inhabitants, the more types of species appear, studies have found. "Undigested carbohydrates allow the whole ecosystem to thrive and flourish," Kashyap says. Most gas made by the microbiome is odorless. It's simply carbon dioxide, hydrogen or methane. But sometimes a little sulfur slips in there."That's when it gets smelly," Kashyap says.
But here's the hitch: Many of the smelly sulfur compounds in vegetables have healthful properties. Take for instance, the broccoli, mustard and cabbage family. These Brassica vegetables are packed with a sulfur compound, called sulforaphane, that is strongly associated with a reduced risk of cancer. Another possible benefit of a little smelly gas? It may reduce the total volume of air in the gut, Kashyap says.