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 is 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 is common to pass gas about 14 times a day.
Most gas is made up of vapors that do not 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 is passed through
- 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.
Foods that cause gas include:
- Fiber that dissolves, or becomes liquid, in water (soluble fiber). Soluble fiber gets soft in the intestines. It is found in oat bran, beans, peas, and
- 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 is found in wheat bran and some vegetables.
- Fructose. A sugar found in onions, artichokes, pears, and wheat. 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. Also
used as a sugar substitute or artificial sweetener in many diet foods and sugar-free
candies and gums.
- Starches. Most starches 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
- Being unable to digest sugar (lactose) in milk products (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
- 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 is 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. 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.
Irritable bowel syndrome is a motility disorder. These disorders can make you feel
bloated, even when you are not.
Other health issues that may cause abdominal bloating include:
- Splenic-flexure syndromes a chronic disorder that may be caused by gas trapped at
bends in the colon.
- Crohn's disease, colon cancer, or any disease that causes a blockage in your intestine.
Internal hernias or scar tissue (adhesions) from surgery.
- Fatty foods can delay stomach emptying and cause bloating and discomfort. They may
not cause too much gas.
- Small intestinal bacterial overgrowth.
There are a few rare, chronic gas diseases that cause belching. These include:
- 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.
- Gas-bloat syndrome. This can happen after surgery for GERD. The surgery creates a one-way valve, or flap,
between your food pipe (esophagus) and your stomach. This valve lets food and gas
go into your stomach.
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?
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.
He or she may also do the following tests:
- Abdominal X-ray.
- Colonoscopy. This test checks for colorectal cancer. It may be done if you are age 50 or older
or have a family member with 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). He or she 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.
You may also need to count the number of times you pass gas during the day.
- Sigmoidoscopy. This test checks the inside of part of your large intestine. It helps to 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
- Upper GI (gastrointestinal) series or barium swallow. If you have chronic belching, you are swallowing too much air. 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.
- 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.
- Taking medicines.
- 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.
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
- Treatments you tried before don’t work now
- Everyone has gas in their digestive tract.
- Gas in your digestive tract is created when you swallow air. It is 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.
Tips to help you get the most from a visit to your healthcare provider:
- Before your visit, write down questions you want answered.
- Bring someone with you to help you ask questions and remember what your provider tells
- At the visit, write down the names of new medicines, treatments, or tests, and any
new instructions your provider gives you.
- If you have a follow-up appointment, write down the date, time, and purpose for that
- Know how you can contact your provider if you have questions.