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Why Do Airplanes Make Me Gassy and Bloated?

US News & World Report - Health logo US News & World Report - Health 1/17/2019 Tamara Duker Freuman
Woman stretching on airplane: Standing up and walking around a few times during a flight can help prevent a buildup of trapped gas. © (Getty Images) Standing up and walking around a few times during a flight can help prevent a buildup of trapped gas.

An acquaintance recently asked me if there is an explanation for his bloating and gas on airplanes. (It was no coincidence that he was fresh off a red-eye flight when he asked.) Was this actually a "thing," he wondered, or was it all in his head?

I assured him that high-altitude bloating is very much a thing, and it even has a name: HAFE, which stands for "high altitude flatus expulsion." There are a few explanations for it. Among them:

1. Low air pressure means expansion of gasses in the gut.

Air pressure decreases at higher altitudes, and the basic laws of physics (Boyle's law, to be precise) dictate that gasses expand as air pressure decreases. Whatever gas is in your gut as you board the plane – or that is created in your bowel during your flight as the result of food choices or that enters into your bowel as the result of swallowed air or ingesting carbonated beverages – is likely to put more pressure against the bowel walls as altitudes rise. Many of us experience this sensation as bloating, or an uncomfortable internal pressure. (Boyle's law also explains why your in-flight water bottle shrivels up upon landing: The air pressure increaseswhen you go quickly from high altitude to low altitude, meaning that the gasses in your water bottle contract, causing the plastic to collapse a bit on itself.)

2. A rapid increase in altitude may also draw more gas into the gut.

Traditionally, researchers had assumed that the increased gas pressure in the bowel (described above) was the sole reason that may people experience more flatulence during air travel. But a 2013 study offered a new hypothesis: that quickly moving from a low altitude to a higher altitude may draw more gas into the bowel in the form of carbon dioxide,which results in a significant uptick in gas-passing.

To test this idea, Australian researchers took a group of eight healthy volunteers on a 40-minute drive up to a ski mountain resort of intermediate altitude – about 5,900 feet, similar to the altitude of Denver. Participants recorded a variety of data, including how many times they passed gas, every hour beginning 18 hours before departure and ending 18 hours after the ascent. Researchers found a near doubling of farts in the post-ascent period, which they believed was too great an increase to attribute solely to the expansion of existing bowel gasses. Rather, they conjectured, the rapid increase in altitude and the decrease in air pressure may have been causing some carbon dioxide that's normally dissolved in the bloodstream to exit the blood and diffuse into the bowel.

The researchers found that peak flatulence occurred 8 to 11 hours after arrival at the higher altitude, if that has any implications for your planning purposes.

3. Cramped airplane quarters mean trapped gas.

Gas pain and bloating can feel much more uncomfortable when gas gets trapped in the bowel, and prolonged sitting in a cramped position can contribute to this.

What to Do to Minimize Gas and Bloating While Flying:

While the likelihood of bloating is somewhat inevitable due to the basic physics involved, here are some measures you can take to minimize its severity:

  • Eat lower FODMAP foods the day before air travel or a high-altitude trip. Certain healthy foods are known to create more intestinal gas than others. These include beans and chickpeas, Brussels sprouts, cauliflower, cashews, onions, garlic, fiber bars, high-lactose dairy foods and "healthy ice creams" that contain inulin fiber or sugar alcohols like mannitol. Collectively, these foods are known as "high FODMAP." Avoiding them for a full day before flying may reduce the load of intestinal gas prone to expansion.
  • Avoid carbonated beverages in flight. The bubbles in your club soda are carbon dioxide gas. This too may expand in the digestive tract during flight, causing more discomfort and distension than usual. Stick to flat drinks if in-flight bloating is an issue for you.
  • Take over-the-counter simethicone (Gas-X or Phazyme) before boarding your flight, and periodically over the course of a longer flight. This medication helps break up larger gas bubbles into smaller, less distending gas bubbles, and can reduce the feeling of gas pressure within the gut. Using it before a flight and periodically during the flight can help reduce feelings of bloating. It's exceptionally safe, so don't be afraid to use it.
  • Get up to walk around a few times during a longer flight. Sitting still in a crunched-up position for hours on end is likely to impede the flow of bowel gasses, causing a bottle-necked "pooling" effect in certain segments of the intestines. This can be painful. Standing up and walking around a few times during a flight can prevent this buildup of trapped gas, especially if you are willing to pass gas in flight. Holding in a fart can make bloating and gas pain way worse, so if the thought of letting it rip causes panic, read on.
  • Wear charcoal-lined undergarments to mask odors. Charcoal filters make excellent odor neutralizers, and that's why they're widely used in things like cat litter boxes, kitchen compost buckets and air-purifier machines. Charcoal liners are also available for underwear, which can help protect your neighbors from the smell of your gas. From disposable charcoal liners you can slip into your undergarments to washable charcoal-lined undergarments (the British company Shreddies makes one of the more fashion-forward assortments), there are many products available to help reduce anxiety about farting on a plane.

Video: Airplanes are dirty but especially these 3 spots (Courtesy: USA Today) 

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