WEBVTT 00:00:08.747 --> 00:00:14.119 Flatulence, or passing gas, is a normal daily phenomenon. 00:00:14.119 --> 00:00:17.232 Most individuals, yes, that includes you, 00:00:17.232 --> 00:00:21.542 will make anywhere from 500-1500 milliliters of gas 00:00:21.542 --> 00:00:25.146 and can pass gas ten to twenty times a day. 00:00:25.146 --> 00:00:27.942 But where does this bodily gas come from? 00:00:27.942 --> 00:00:33.792 A small proportion may come from ingesting air during sleep, or at other times, 00:00:33.792 --> 00:00:38.318 but the majority of gas is produced by bacteria in our intestines 00:00:38.318 --> 00:00:41.768 as they digest parts of food which we cannot. 00:00:41.768 --> 00:00:44.367 Our intestine is home to trillions of bacteria 00:00:44.367 --> 00:00:47.454 living in a symbiotic relationship with us. 00:00:47.454 --> 00:00:50.985 We provide them with a safe place to stay and food to eat. 00:00:50.985 --> 00:00:54.536 In exchange, they help us extract energy from our food, 00:00:54.536 --> 00:00:58.760 make vitamins for us, like vitamin B and K, boost our immune system, 00:00:58.760 --> 00:01:03.462 and play an important role in gastrointestinal barrier function, 00:01:03.462 --> 00:01:07.436 motility and the development of various organ systems. 00:01:07.436 --> 00:01:11.456 Clearly, it's in our best interest to keep these bacteria happy. 00:01:11.456 --> 00:01:15.333 Gut bacteria get their nutrition primarily from undigested food, 00:01:15.333 --> 00:01:20.131 such as carbohydrates and proteins, which come to the large intestine. 00:01:20.131 --> 00:01:24.077 They ferment this undigested food to produce a wide range of compounds, 00:01:24.077 --> 00:01:29.036 such as short-chain fatty acids and, of course, gases. 00:01:29.036 --> 00:01:32.667 Hydrogen and carbon dioxide are the most common gaseous products 00:01:32.667 --> 00:01:35.746 of bacterial fermentation, and are odorless. 00:01:35.746 --> 00:01:40.996 Some people also produce methane due to specific microbes present in their gut. 00:01:40.996 --> 00:01:44.001 But methane is actually odorless, too. 00:01:44.001 --> 00:01:45.689 Well then, what stinks? 00:01:45.689 --> 00:01:50.010 The foul smell is usually due to volatile sulfur compounds, 00:01:50.010 --> 00:01:54.829 such as hydrogen sulfide and methanethiol, or methyl mercaptan. 00:01:54.829 --> 00:01:58.798 These gases, however, constitute less than 1% of volume, 00:01:58.798 --> 00:02:02.960 and are often seen with ingestion of amino acids containing sulfur, 00:02:02.960 --> 00:02:07.963 which may explain the foul smell of gas from certain high protein diets. 00:02:07.963 --> 00:02:11.623 Increased passage of gas is commonly noticed after eating foods 00:02:11.623 --> 00:02:14.601 with high amounts of indigestible carbohydrates, 00:02:14.601 --> 00:02:21.436 like beans, lentils, dairy products, onions, garlic, leeks, radishes, 00:02:21.436 --> 00:02:29.287 potatoes, oats, wheat, cauliflower, broccoli, cabbage, and brussel sprouts. 00:02:29.287 --> 00:02:30.657 Humans lack the enzymes, 00:02:30.657 --> 00:02:35.509 so the bacteria able to ferment complex carbohydrates take over, 00:02:35.509 --> 00:02:38.530 and this naturally leads to more gas than usual. 00:02:38.530 --> 00:02:42.061 But if you feel uncomfortable, bloated or visibly distended, 00:02:42.061 --> 00:02:46.868 this may indicate impaired movement of gas along the gastrointestinal track. 00:02:46.868 --> 00:02:49.394 It's important not to just blame certain foods 00:02:49.394 --> 00:02:51.894 for gas and bloating and then avoid them. 00:02:51.894 --> 00:02:55.685 You don't want to starve the bacteria that digest these complex carbohydrates, 00:02:55.685 --> 00:03:00.047 or they'll have to start eating the sugars in the mucus lining of your intestines. 00:03:00.047 --> 00:03:03.544 Your personal gas will vary based on what you eat, 00:03:03.544 --> 00:03:05.734 and what bacteria are in your gut. 00:03:05.734 --> 00:03:08.013 For example, from the same starting sugar, 00:03:08.013 --> 00:03:12.836 the bacteria clostridium produces carbon dioxide, butyrate and hydrogen, 00:03:12.836 --> 00:03:18.804 while propionibacterium can produce carbon dioxide, propionate and acetate. 00:03:18.804 --> 00:03:22.695 At the same time, methanogens can use hydrogen and carbon dioxide 00:03:22.695 --> 00:03:26.245 produced by other bacteria to generate methane, 00:03:26.245 --> 00:03:31.213 which can reduce the total volume of gas by using up hydrogen and carbon dioxide. 00:03:31.213 --> 00:03:34.271 So there's a complex web among intestinal bacteria 00:03:34.271 --> 00:03:38.438 allowing them to flourish by either directly consuming undigested food, 00:03:38.438 --> 00:03:41.751 or using what other bacteria produce. 00:03:41.751 --> 00:03:46.160 This interaction largely determines the amount and type of gas produced, 00:03:46.160 --> 00:03:50.409 so gas production is a sign that your gut bacteria are at work. 00:03:50.409 --> 00:03:55.500 But in some instances, people may develop abnormal increased flatulence. 00:03:55.500 --> 00:03:58.784 A common example is lactose intolerance. 00:03:58.784 --> 00:04:02.101 Most individuals have the enzyme for breaking down lactose, 00:04:02.101 --> 00:04:05.760 a sugar present in milk and milk-derived products. 00:04:05.760 --> 00:04:10.163 But some people either lack it entirely, or have a reduced amount, 00:04:10.163 --> 00:04:12.901 such as after a gastrointestinal infection, 00:04:12.901 --> 00:04:16.954 so they're unable to digest lactose products and may experience cramping, 00:04:16.954 --> 00:04:21.304 along with increased flatulence due to bacterial fermentation. 00:04:21.304 --> 00:04:23.668 But remember, most gas is produced 00:04:23.668 --> 00:04:27.142 as a natural result of bacterial fermentation in the intestine, 00:04:27.142 --> 00:04:30.081 and indicates healthy functioning of the gut. 00:04:30.081 --> 00:04:34.673 The amount and type can vary based on your diet and the bacteria in your intestine. 00:04:34.673 --> 00:04:39.611 Exercise social courtesy while passing gas, and do try to forgive your bacteria. 00:04:39.611 --> 00:04:41.774 They're only trying to be helpful.