If much to your own chagrin, you've ever accidentally let one (OK, several) rip in public, you're not alone. Battling a discretionary war on burps and farts can be trying - and that's true for all of us.

Despite our avid denials, each of us passes upwards of about one litre of gas, 14 times a day on average. Many farts are actually odourless and have nothing to do with digestion. Stink factor notwithstanding, farting, along with burping, carries with it cringe-inducing social stigma. Nobody wants to cut one loose at an inopportune time, such as in a yoga class or during sex. But the frustrating thing about having gas is that it can feel random, hard to control, and difficult to pin on anything in particular. In fact, there are several surprising things that cause gas that you do have some control over.

About half of all burps and farts are caused by aerophagia, otherwise known as swallowing air. Bloat is a different beast altogether: "Although many people who are bloated feel like they have gas, they don't technically have extra gas - they just have the sensation of bloatedness," says gastroenterologist Dr Patricia Raymond.

"Most of us know when we poorly absorb something we eat, it travels down to the colon, where the bacteria spew out smelly gas in small volume," says Raymond. "This gas smells bad, like rotting eggs-think of your high school days' silent but deadly moniker." But non-smelly, voluminous gas, expressed as noisy farts or big burps, means too much air is the culprit. "The GI tract was not made to absorb gas," says Raymond. "If you are putting it down your stomach it will either come back up or go back out further down."

Here are nine unexpected things that may be causing you to pass gas-and how to find relief.

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