Flying can cause bloating, a common form of discomfort medically known as abdominal distension or barotrauma. This uncomfortable sensation is the result of gas already present in your digestive tract expanding when the ambient pressure drops at cruising altitude. Understanding this simple physics principle and making minor adjustments to your routine can significantly alleviate the issue.
The Physics of Gas Expansion in the Body
The primary reason for flight-related bloating is explained by a fundamental principle of physics known as Boyle’s Law. This law dictates that for a fixed amount of gas at a constant temperature, the volume of that gas is inversely proportional to the pressure exerted on it. As the pressure decreases, the volume the gas occupies must increase. Commercial airliners fly at high altitudes where the external atmospheric pressure is much lower than at sea level. While the cabin is pressurized, most commercial cabins maintain an internal pressure equivalent to an altitude of 6,000 to 8,000 feet above sea level. This pressure difference is significant enough to cause a noticeable expansion of gases trapped within the body’s cavities, including the stomach and intestines. Gas trapped in the gastrointestinal tract can expand by up to 25% when ascending to a cabin altitude of 8,000 feet. The resulting increase in volume puts pressure on the walls of the intestines and abdomen, leading to the familiar feeling of tightness, fullness, and pain associated with bloating.
Dietary and Lifestyle Factors Increasing Risk
The physics of pressure change only exacerbates existing gas, meaning the amount of gas already in your system is the factor you can control. A significant source of intestinal gas is the fermentation of undigested carbohydrates and fibers by bacteria in the colon, a process that produces gases like hydrogen, carbon dioxide, and methane. Consuming foods high in fermentable fiber before a flight creates a larger volume of gas that is ready to expand.
Foods known to be high gas producers should be moderated before flying due to their gas-producing nature. These include:
- Cruciferous vegetables, such as broccoli, cabbage, and cauliflower.
- Beans and lentils.
- Whole grains and high-fiber snacks.
Additionally, beverages containing dissolved gas, like carbonated sodas, sparkling water, and beer, directly introduce extra carbon dioxide into the stomach, setting the stage for more dramatic expansion at altitude.
Lifestyle habits during travel also contribute to increased gas. Swallowing air, medically termed aerophagia, is a common issue when people chew gum, suck on hard candies, talk excessively, or drink rapidly through a straw. This ingested air gets trapped in the stomach and small intestine. Prolonged sitting further compounds the problem by slowing down the natural wave-like contractions of the digestive muscles, known as peristalsis, which normally help move gas through the system.
Actionable Strategies for Prevention and Relief
Preventing flight-related bloating begins with a pre-flight adjustment to your diet, focusing on low-residue foods for 24 hours before departure. A low-residue diet limits the intake of foods that are difficult to digest and thus minimizes the amount of fermentable material reaching the colon. This involves choosing refined grains, such as white rice and white bread, over high-fiber whole grains, and selecting peeled, cooked vegetables over raw, fibrous ones.
During the flight, managing your behavior can reduce both gas production and air swallowing. Avoid carbonated drinks and alcohol entirely, as they significantly increase the volume of gas introduced into the stomach. Instead, focus on drinking plain water to maintain hydration, which supports proper digestive function. Instead of remaining sedentary, stand up and walk the aisles every hour or perform gentle seated stretches to encourage intestinal motility and help move trapped gas along.
For immediate relief during the flight, over-the-counter medications can be highly effective. Simethicone is an anti-flatulent agent that works by decreasing the surface tension of gas bubbles in the gastrointestinal tract, causing them to break down into smaller, more easily passed bubbles. Activated charcoal can also be taken, as its porous structure traps gas molecules and helps reduce the volume of intestinal gas. These two compounds are sometimes combined in relief products and can be taken before or during the flight to mitigate the effects of gas expansion.