Obesity and Bariatric Surgery

Gas in the Digestive Tract

What is gas in the digestive tract?

Gas in your digestive tract is made when:

You swallow air
Some foods are broken down by the good bacteria in your colon

Everyone has gas. It may be painful and embarrassing, but it's not dangerous. Your body gets rid of gas by burping or by passing it through your rectum. Most people make about 1 to 4 pints of gas a day. It's common to pass gas about 14 times a day.

Most gas is made up of vapors that don't smell. These include carbon dioxide, oxygen, nitrogen, hydrogen, and sometimes methane. The bacteria in your large intestine give off gases that have sulfur. These gases have a bad smell.

What causes gas in the digestive tract?

Gas in your digestive tract is caused by 2 things:

Swallowing air (aerophagia). This can happen when you eat or drink too quickly, chew gum, smoke, or wear loose dentures. Having postnasal drip can also cause this. Most air that you swallow leaves your stomach when you burp or belch. Some of the gas that is left is absorbed into your small intestine. A small amount goes into the large intestine. It's passed through your rectum.

Breaking down of some undigested foods by good bacteria found in the large intestine (colon). Carbohydrates are nutrients found in sugar, starches, and fiber. Some carbohydrates are not digested or absorbed in your small intestine. When food is not digested, it passes into your large intestine. The undigested food is then broken down into small parts by good bacteria in your colon. This process makes hydrogen and carbon dioxide. In some cases, it also makes methane gases. These gases are passed through your rectum.

Foods that often cause gas

Most foods with carbohydrates can cause gas. Fats and proteins don’t cause much gas.

FODMAP is an acronym for poorly digested carbohydrates and sugars in the diet. A diet low in FODMAPs can help gas and bloating. FODMAPs occur naturally in some foods or as artificial sweeteners.

Foods and FODMAPs that cause gas include:

Fiber that dissolves, or becomes liquid, in water (soluble fiber). Soluble fiber gets soft in the intestines. It's found in oat bran, beans, peas, and most fruits.
Fiber that does not dissolve in water (insoluble fiber). Insoluble fiber does not get soft as it moves through the intestines. It does not make much gas. It's found in wheat bran and some vegetables.
Fructose. A sugar found in onions, artichokes, pears, and wheat. It's also used as a sweetener in some soft drinks and fruit drinks.
Lactose. A natural sugar found in milk and milk products such as cheese and ice cream. Also found in processed foods such as bread, cereal, and salad dressing.
Raffinose. A complex sugar found in beans, cabbage, Brussels sprouts, broccoli, asparagus, other vegetables, and whole grains.
Sorbitol. A sugar found naturally in fruits including apples, pears, peaches, and prunes. It's also used as a sugar substitute or artificial sweetener in many diet foods and sugar-free candies and gums.
Starches. Most starches can cause gas, including potatoes, corn, noodles, and wheat. Rice is the only starch that does not cause gas.

Who is at risk for gas in the digestive tract?

Some health problems can cause you to make more gas in your digestive tract. These include:

Being unable to digest sugar (lactose) in milk products, called lactose intolerance
Irritable bowel syndrome, an intestinal problem
Having inflammation in the intestines, such as inflammatory bowel disease
Stomach disorders such as peptic ulcer disease and heartburn or GERD (gastroesophageal reflux disease)
Health problems that cause constipation

What are the symptoms of gas?

Each person’s symptoms may vary. The most common symptoms of gas are:

Belching. Belching during or after meals is normal. But belching too often can be a problem. You may be swallowing too much air. And you may be letting the air out before it enters your stomach. Chronic belching may also mean that you have an upper GI (gastrointestinal) disorder such as peptic ulcer disease, GERD, or gastritis.

Passing gas, or flatulence. Passing gas through the rectum is called flatulence. It's normal to pass gas 14 to 23 times a day.

Abdominal pain. Gas in your intestine may be painful. When it collects on the left side of your colon, the pain may seem like heart disease. When it collects on the right side of your colon, the pain may feel like gallstones or appendicitis.

Abdominal bloating (distention). In most cases, this happens when the muscles of your intestine don’t move or contract in the normal way. This type of problem is called an intestinal motility disorder, which can make you feel and look bloated from your belly being swollen with gas.

Other health issues that may cause abdominal bloating include:

Crohn's disease, colon cancer, or any disease that causes a blockage in your intestine, as well as internal hernias or scar tissue (adhesions) from surgery
Fatty foods can delay stomach emptying and cause bloating and discomfort, but they may not cause too much gas
Small intestinal bacterial overgrowth

There are a few rare, chronic gas diseases that cause belching. One of these is:

Meganblase syndrome. This causes chronic belching. It happens after eating big, heavy meals. You will swallow a large amount of air. You will also have a big bubble of gas in your stomach. This will make you feel very full and have trouble breathing. These symptoms feel like a heart attack.

The symptoms of gas may look like other health problems. Always see your healthcare provider to be sure.

How is gas in the digestive tract diagnosed?

Many times, you will not need testing for symptoms of intestinal gas. In some cases, you may have gas symptoms because of a serious health problem. Always see your healthcare provider to be sure.

Your healthcare provider will look at your past health and give you a physical exam. The following tests may also be done:

Abdominal X-ray. An X-ray machine sends a beam of radiation through the abdomen. The image is recorded on special film or a computer.
Colonoscopy. This test checks for colorectal cancer, polyps, and other colon disease. Colonoscopy is recommended if you are age 45 or older, or maybe even earlier if you have a family history of colorectal cancer. A colonoscopy looks at the entire length of the large intestine. This test can often help find abnormal growths, inflamed tissue, ulcers, and bleeding. A long, flexible, lighted tube (colonoscope) is inserted in through your rectum and up into your colon. Your healthcare provider uses the tube to see the lining of the colon and to take a tissue sample (biopsy). They may also be able to fix some problems that are found.
Food diary. You may be asked to keep a diary of what you eat and drink for a certain time period and record your symptoms.
Sigmoidoscopy. This test checks the inside of the last part of your large intestine. It helps tell what is causing diarrhea, belly pain, constipation, abnormal growths, and bleeding. A short, flexible, lighted tube (sigmoidoscope) is put into your intestine through the rectum. This tube blows air into your intestine to make it swell. This makes it easier to see inside.
Upper endoscopy (EGD). A flexible tube with a light is passed down your mouth to look at the upper gastrointestinal tract, the esophagus, stomach, and duodenum.
Upper GI (gastrointestinal) series or barium swallow. If you have chronic belching, you may be swallowing too much air. If your provider is concerned about other reasons for your symptoms, you may need testing. This test checks the organs at the top of your digestive system. It checks the esophagus, stomach, and the first part of the small intestine (duodenum). You will swallow a metallic fluid called barium. Barium coats the organs so that they can be seen on an X-ray.
Esophageal manometry and impedance test. This test can show how your esophagus contracts and if you are swallowing and belching excess air.
Blood test. Depending on your symptoms, a blood test for celiac disease may be done.

How is gas in the digestive tract treated?

Your healthcare provider will make a care plan for you based on:

Your age, overall health, and past health
How serious your case is
How well you handle certain medicines, treatments, or therapies
If your condition is expected to get worse
What you would like to do

You can reduce some of your gas pain by:

Changing your diet. Don’t have soda or other fizzy (carbonated) drinks. Don’t take any foods that might give you gas. Lactose-free dairy products and a low FODMAP diet are often helpful.
Taking medicines. There are many over-the-counter medicines for gas. Ask your healthcare provider or pharmacist for suggestions.
Reducing the amount of air you swallow. Don’t chew gum or suck on hard candies. Try to eat more slowly. If you wear dentures, have your dentist make sure they fit well.
Depending on the cause of your gassiness, prescription medicines may be used.

Can gas in the digestive tract be prevented?

You can’t stop all gas in the digestive tract. But you can reduce the amount of gas made in your digestive system. Don’t take foods or drinks that seem to give you more gas. And follow your healthcare provider’s advice.

When should I call my healthcare provider?

In most cases, having gas in your digestive tract is not serious. But you should call your healthcare provider if:

Your symptoms increase or change
You have new symptoms such as constipation, diarrhea, or weight loss
You are vomiting
You have blood in the stool or black, tarry stool
You have pain that does not go away
Treatments you tried before don’t work now

Key points about gas in the digestive tract

Everyone has gas in their digestive tract.
Gas in your digestive tract is created when you swallow air. It's also caused by the breakdown of some foods by good bacteria in your colon.
Your body gets rid of gas by burping or by passing it through your rectum.
Most foods with carbohydrates cause gas.
The most common symptoms of gas are burping, passing gas, belly or abdominal bloating, and abdominal pain.
You can reduce gas pain by changing your diet, taking medicines, and reducing how much air you swallow.

Next steps

Tips to help you get the most from a visit to your healthcare provider:

Know the reason for your visit and what you want to happen.
Before your visit, write down questions you want answered.
Bring someone with you to help you ask questions and remember what your provider tells you.
At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you.
Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
Ask if your condition can be treated in other ways.
Know why a test or procedure is recommended and what the results could mean.
Know what to expect if you do not take the medicine or have the test or procedure.
If you have a follow-up appointment, write down the date, time, and purpose for that visit.
Know how you can contact your provider if you have questions.