Passing gas 101: What your flatulence patterns mean for your health

Passing gas: Everybody does it – and no one wants to admit it.

This embarrassing habit may seem foul, but breaking wind is simply an unavoidable byproduct of our daily digestion.  In fact, the average individual can pass gas anywhere from 13 to 21 times a day.

But your gaseous patterns can actually speak volumes about your health, especially in regards to your eating habits, and they may even serve as an indication of larger digestive health issues.

“People who produce excessive amounts of gas and particularly foul smelling gas – if you’re eating a super high fiber diet, that could be part of it,” Dr. Anish Sheth, a gastroenterologist in Princeton, N.J., told  “But if it’s something that’s persistent, and your significant other is noticing it, it could be a problem.”

Gaseous origins

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    During digestion, food particles pass from the stomach to the small intestine, where the large majority of food absorption takes place.  Then, undigested particles pass into the large intestine and the colon, where bacteria break the rest of it down.  This bacterial fermentation ultimately releases the main components of intestinal gas – also known as flatus.

    According to gastroenterologists, carbohydrates such as sugars, starches and fibers produce the most gas in the colon, as they do not get absorbed as completely in the small intestine.  This is why vegans and vegetarians tend to be more flatulent than their meat-eating counterparts.

    “A lot of what you eat really can produce more gas,” Dr. Gina Sam, director of the Mount Sinai Gastrointestinal Motility Center at Mount Sinai Hospital in New York City, told “So if a person is eating a lot of beans, vegetables like broccoli, cauliflower or Brussels sprouts, whole wheat or bran, even sodas like fruit drinks with fructose sweetener, they can have more gas….What patients can do is decrease these products and go more on a protein diet [to decrease their gas].”

    Mostly comprised of carbon dioxide, flatus also contains an eclectic blend of non-smelling gasses, including oxygen, nitrogen, hydrogen and sometimes methane.  The foul smelling odor actually comes from a combination of sulfur compounds, which comprise less than 1 percent of the gas’s composition. According to Sheth, many red meats and protein contain high amounts of sulfur – so while herbivores may pass gas more often, flatus from meat eaters may smell much worse.

    And as for that all too familiar gaseous sound?  It’s a result of the gas passing through the rectum, causing vibrations in the anal opening.  The auditory pitch all depends on the tightness of the sphincter as well as the velocity of the gas being expelled.

    While individuals can sometimes voluntarily control their flatulence during the day by tightening their rectum, all bets are off during the nighttime hours.

    “People fart when they sleep, [because] your anal sphincter relaxes while you sleep,” said Sheth, who is also the co-author of “What’s Your Poo Telling You.”  “No one realizes it, unless their partner tells them.”

    Gas as a symptom

    Although passing gas is a completely normal physiological action, too much flatulence may be a telling sign of an even bigger problem – such as missing components in the intestines.

    “Some people may lack certain enzymes in their small intestines,” Sam said. “A common problem is lactose intolerance, where individuals lack the lactase enzyme, which breaks down lactose” – a sugar found in milk and most dairy products.  “This causes diarrhea and bloating, because that [sugar] stays in the small bowel and causes more gas production.”

    While excessive flatulence can reveal a lack of compounds in the gastrointestinal (GI) tract, it can also indicate an overabundance of GI components.

    Unlike the large intestines and colon, the small intestines contain much less bacteria, and the bacteria that do reside there are much different than the bacteria in the colon.  But when people suffer from small intestinal bacterial overgrowth (SIBO), an abnormally large amount of bacteria resides in the small intestine, and the bacteria are more like the ones living in the colon. As a result, people will experience much more flatus, along with bloating and diarrhea.

    “When you have an overgrowth of bacteria in the small intestines, the bacteria take in more than their fair share of food you’re eating… So in a normal situation, gas is produced in the colon.  But in people with SIBO, if you have these bad bacteria overgrowing in the small intestine, they’re even [breaking down] regular stuff [in the small intestines], so you can have excess gas.”

    According to Sheth, SIBO is very rare, but it can be caused by certain diets, stress and a bad mix of medications. Additionally, people who have recently had surgery on their GI tracts or have just overcome a GI bug like norovirus may also experience an imbalance in bacteria.

    Particularly foul smelling flatus may also be a symptom of infection or an even bigger health issue.

    “One of the things that makes stool smell worse than it normally does is if you have a bleeding ulcer; those people will not only have foul smelling stool but also foul smelling gas,” Sheth said.  “Certain infections like giardia, which occurs in people who swim a lot in the summer time – it’s notorious for causing really foul smelling flatulence.”

    Excessive flatulence or foul smelling flatus is pretty rare and is often accompanied by changes in stool and digestion.  So if you’re noticing significant fluctuations in your digestive health, it may be time to see a gastroenterologist.

    But otherwise, passing gas is simply part of everyday life – so you’ll just have to stick to denying it if you supplied it.