"In two thousand and four in a tiny town. A young woman named Rebecca Gould was brutally murdered nearly fifteen years later her killer is still on the loose. It's just really surreal walking around. Don't mention so much. Guys out there yell. I'm Katherine towns, and this is Helen gone catch new episodes by subscribing at apple podcasts or on the iheartradio app or wherever you listen to podcasts. Welcome to brain stuff from how stuff works. Hey, brain stuff. I'm Lauren Volvo bomb, and I've got another classic episode for you today in it. Our former host Christian Sager answers, a basic yet nonetheless burning question, why do we fart? Rain stuff. It's Christian Sager. So in the late eighteen hundreds there is this French guy and his name was lapel Mon, and he was one of the stars of Moulin Rouge, people would come from far and wide just to watch this guy fart. Yeah. To watch him fart, lapenne them on you see was a professional flatulence, which as it turns out is still sort of thing. And certainly it's a dream job for some. But if you want to move out of the ranks of amateur windbreakers, an into those stinking hallowed halls of the professionally flatulent, you will need to know if thing or two about farts, like what are they why do they happen? And why do they smell so bad? Well, first things first everyone farts every single person. Yes. You to listening to this. You do to to not far would be medically fascinating and probably dangerous on average. Most people are passing about one. Leader of gas a day spread out over thirteen to wait for it. Twenty one incidents. That's Twenty-one separate times in one day, the composition of a fart varies widely. But usually what we're smelling is something that's mostly nitrogen along with oxygen carbon dioxide and even methane. This gas itself comes from several sources the air you swallow gas that enters your intestines from your bloodstream and so on but about seventy five percent of your farts are created in your lower intestine. And unfortunately, not by you see the bacteria living inside you right now, they comprise a micro Buyum all of their own. And when we say, it's intricate. We mean it so intricate that David Attenborough could make a documentary about it these bacteria form this thriving empire with billions of tiny separate organisms living inside their host. And that's you. They're living with you. And symbiosis. Now flatulence occurs when food passes through your stomach and small intestine without fully breaking down. So what does this mean, this means that the food hits the large intestine in an undyed jested state? So for example, let's look at lactose which is present in dairy products like milk and cheese, if you're lactose intolerant than you lack the enzyme that breaks lactose into sugar molecules for the bloodstream without this lactose just breezes through your stomach and small intestine into your large intestine where it becomes the special of the day for billions of Hungary bacteria, those guys love lactose. And if you're not going to digest it they will as they digest this lactose, they emit a number of gases, including methane, hydrogen carbon dioxide and hydrogen sulfide, which is responsible for the unpleasant, aroma. This process is similar to how yeast produces carbon dioxide to. Leaven bread. And speaking of food. It's true that some foods do produce more flatulence primarily because they contain more indigestible carbohydrates. I'm looking at you beans, nutrient dense, vegetables and fiber, rich foods all have a reputation for nibbling flatulence, that's not necessarily a bad thing. See a scientists learn more about the relationship between diet health and a person's microbiome they're discovering that these flatulent foods may encourage the growth of beneficial bacteria in your gut when they're producing that next embarrassing puff of gas. They're also making molecules to protect your intestinal lining and prevent infections. So remember the next time you're silent crime accidentally ends up sounding like stuttering, trumpet, your intestinal bacteria are the real culprits. They are the ones actually farting. And and look I want to emphasize this. They are farting inside of you. You and then you fart their farts out. Are we clear on that part, which leads us to the bigger question of the day? Who are we fighting inside? Episode was written by Ben Bullen and produced by Tyler clang to hear more weird and funny true stories from Ben check out his show ridiculous history. Available wherever you get your podcast. And of course for more on this and lots of other easily digestible topics visit our home planet. How stuff works dot com. Hey, Brian Steph listeners in Lumine today. I wanted to tell you about one of our compatriot podcasts here at how stuff works Daniel and explain the universe in which physicist, Daniel Whiteson and cartoonist or hey cham- breakdown. All the amazing things, we know and don't know about our wild universe. They talk through some of the biggest questions and science like how did the universe begin? What is everything made of what's the Higgs bows on can we travel back in time? And where do my socks go after I put them in the dryer. It's recommended for anyone who wants their mind blown by awesome science or commuters who just wish they were out in space, new episodes, come out approximately pied vita by two times a week on Tuesdays and Thursdays. You can listen and subscribe to Daniel or hey, explained the universe on apple podcasts the iheartradio app or wherever you listen to podcasts."