What causes gas in the stomach?

Author:

Annamaria Ambrosova

Most of the gas in our digestive system, about 90%, comes from air that we swallow. This may not be surprising, since we swallow around 70 times per hour while we are awake. We also swallow extra air when we eat or drink foods that contain a lot of air, such as carbonated beverages. The swallowed air first enters the stomach and then moves into the small intestine. Gas usually passes quickly through the small intestine and rarely causes problems there. However, when it reaches the large intestine (colon), it can build up and cause discomfort. This is partly because new gas is also produced there during digestion. Gas trapped in the stomach can also cause discomfort, such as bloating or belching.

How to reduce swallowed air

You can reduce the amount of air you swallow by:

Chewing your food thoroughly
Eating slowly
Avoiding chewing gum and sucking on hard candies (these increase air swallowing)
Quitting smoking, as smoking increases swallowed air
Managing stress, since stress can affect breathing patterns and cause you to swallow more air

Gas produced during digestion

The remaining 10% of intestinal gas is produced by bacteria in the large intestine. Some foods are not fully broken down by our digestive system. Bacteria use these undigested food components as fuel and produce gas in the process.

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A small amount of this gas enters the bloodstream and leaves the body through the lungs. Some is used by other bacteria. Most of it, however, leaves the body through the rectum.

Although digestion contributes a smaller share of total gas, certain foods can increase gas production more than others. These include:

Cabbage, brussels sprouts, cauliflower
Peas and beans
Wheat bran
Onions
Sugar alcohols such as sorbitol and xylitol

Rice is one of the few starchy foods that typically produces little to no gas.

Conditions such as lactose intolerance and gluten intolerance can also increase gas production, especially when undigested nutrients remain in the intestine and feed gas-producing bacteria.

How to get rid of gas?

Most gas leaves the body without us noticing. A significant amount is released during sleep, and only a small portion contains sulphur compounds that cause odour. On average, a person passes gas about 20–25 times per day.

There is no medication that completely removes gas from the digestive system. Instead, managing gas usually involves lifestyle changes, such as:

Regular physical activity
Healthy toilet habits
Allowing yourself to burp or pass gas without embarrassment

Gas can leave the body in two main ways: through the mouth (belching) or through the rectum (flatulence). Allowing gas to pass naturally can relieve discomfort. Physical movement also helps gas move through the intestines more easily.

When to seek medical advice

In very rare cases, excessive gas may be caused by a more serious condition, such as a blockage in the digestive tract. You should contact a healthcare provider if: