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Gas in the Digestive Tract

National Digestive Diseases Information Clearinghouse

What is gas? Gas is air in the digestive tract—the large, muscular tube that extends from the to the , where the movement of muscles, U.S. Department along with the release of and of Health and Mouth Services , allows for the of food. Gas leaves the body when people burp through the NATIONAL mouth or pass gas through the anus. INSTITUTES OF HEALTH Gas is primarily composed of , oxygen, , , and sometimes . Flatus, gas passed through the anus, may also contain small amounts of Large gasses that contain sulfur. Flatus that intestine contains more sulfur gasses has more odor. Everyone has gas. However, many people think they burp or pass gas too often and that Small Colon they have too much gas. Having too much intestine (shaded) gas is rare.

Anus What causes gas? Gas in the digestive tract is usually caused The digestive tract by air and by the breakdown of certain foods in the by . allows some gas to leave the stomach. The remaining gas moves into the Everyone swallows a small amount of air , where it is partially absorbed. when and . The amount of air A small amount travels into the large swallowed increases when people intestine for release through the anus. • eat or drink too fast The stomach and small intestine do not • smoke fully digest some —sugars, , and fiber found in many foods. • chew gum This undigested food passes through the • suck on hard candy small intestine to the large intestine. Once there, undigested carbohydrates are broken • drink carbonated or “fizzy” drinks down by bacteria in the large intestine, which • wear loose-fitting dentures release hydrogen and carbon dioxide in the process. Other types of bacteria in the large digest carbohydrates and the type of bacteria intestine take in hydrogen gas and create present in the intestines. methane gas or , the most Some foods that may cause gas include common sulfur gas in flatus. • beans Studies have detected methane in the breath of 30 to 62 percent of healthy adults.1 A • vegetables such as broccoli, cauliflower, larger percentage of adults may produce cabbage, brussels sprouts, onions, methane in the intestines, but the levels may mushrooms, artichokes, and asparagus be too low to be detected. Research suggests • fruits such as pears, apples, and peaches that people with conditions that cause are more likely to produce • whole grains such as whole wheat and detectable amounts of methane.1 More bran research is needed to find out the reasons • sodas; fruit drinks, especially apple for differences in methane production and juice and pear juice; and other drinks to explore the relationship between methane that contain high-fructose corn , a and other health problems. sweetener made from corn Some of the gas produced in the intestines is • and milk products such as cheese, absorbed by the bloodstream and carried to ice , and yogurt the , where it is released in the breath. • packaged foods—such as bread, cereal, Normally, few bacteria live in the small and salad —that contain small intestine. Small intestinal bacterial amounts of , a sugar found in overgrowth is an increase in the number of milk and foods made with milk bacteria or a change in the type of bacteria • sugar-free candies and that in the small intestine. These bacteria can contain sugar alcohols such as , produce excess gas and may also cause , and and weight loss. Small intestinal bacterial overgrowth is usually related to diseases or disorders that damage the What are the symptoms digestive system or affect how it works, of gas? such as Crohn’s disease—an inflammatory The most common symptoms of gas bowel disease that causes , or are burping, passing gas, , and swelling, and irritation of any part of the or discomfort. However, not gastrointestinal (GI) tract—or diabetes. everyone experiences these symptoms. Which foods cause gas? Burping. Burping, or belching, once in a while, especially during and after meals, Most foods that contain carbohydrates can is normal. However, people who burp cause gas. In contrast, and frequently may be swallowing too much air cause little gas. Foods that produce gas in and releasing it before the air enters the one person may not cause gas in someone stomach. else, depending on how well individuals Some people who burp frequently may have an upper GI disorder, such as 1Sahakian AB, Jee SR, Pimentel M. Methane and the gastroesophageal reflux disease—a chronic . Digestive Diseases and Sciences. condition in which stomach contents flow 2010;55(8):2135–43. Epub 2009 Oct 15. 2 Gas in the Digestive Tract back up into the esophagus. People may Abdominal pain and discomfort. People believe that swallowing air and releasing it may feel abdominal pain or discomfort when will relieve the discomfort, and they may gas does not move through the intestines intentionally or unintentionally develop a normally. People with IBS may be more habit of burping to relieve discomfort. sensitive to gas and feel pain when gas is present in the intestines. Passing gas. Passing gas around 13 to 21 times a day is normal.2 is excessive gas in the stomach or intestine that How is the cause of gas can cause bloating and flatus. Flatulence found? may be the result of problems digesting People can try to find the cause of gas on certain carbohydrates. their own by keeping a diary of what they eat Bloating. Bloating is a feeling of fullness and and drink and how often they burp, pass gas, swelling in the , the area between or have other symptoms. A diary may help the chest and . Problems digesting identify specific foods that cause gas. carbohydrates may cause increased gas and A health care provider should be consulted if bloating. However, bloating is not always caused by too much gas. Bloating may • symptoms of gas are bothersome result from diseases that affect how gas • symptoms change suddenly moves through the intestines, such as rapid gastric emptying, or from diseases that cause • new symptoms occur, especially in intestinal obstruction, such as colon . people older than age 40 People who have had many operations, • gas is accompanied by other symptoms, internal , or bands of internal scar such as constipation, diarrhea, or weight called adhesions may experience loss bloating. The health care provider will ask about Disorders such as dietary habits and symptoms and may ask a (IBS) can affect how gas moves through person to keep a food diary. Careful review the intestines or increase pain sensitivity of diet and the amount of burping or gas in the intestines. IBS is a functional GI passed may help relate specific foods to disorder, meaning that the symptoms are symptoms and determine the severity of the caused by changes in how the digestive tract problem. Recording gas symptoms can help works. The most common symptoms of IBS determine whether the problem is too much are abdominal pain or discomfort, often gas in the intestines or increased sensitivity reported as cramping, along with diarrhea, to normal amounts of gas. constipation, or both. IBS may give a sensation of bloating because of increased If milk or milk products are causing gas, the sensitivity to normal amounts of gas. health care provider may perform blood or breath tests to check for , Eating a lot of fatty food can delay stomach the inability or insufficient ability to digest emptying and cause bloating and discomfort, lactose. Lactose intolerance is caused by a but not necessarily too much gas. deficiency of the lactase, which is needed to digest lactose. The health care 2Gas-related complaints. The Merck Manuals provider may suggest avoiding milk products Online Medical Library. www.merckmanuals.com/ for a short time to see if symptoms improve. professional/sec02/ch008/ch008d.html. Updated October 2007. Accessed June 26, 2012. 3 Gas in the Digestive Tract The health care provider may perform a lacks to digest the sugar in beans and physical exam and order other types of many vegetables. The enzyme comes diagnostic tests, depending on a person’s in liquid and form. Five drops symptoms. These tests can rule out serious are added per serving or one tablet is health problems that may cause gas or swallowed just before eating to break symptoms similar to those of gas. down the gas-producing sugars. Beano has no effect on gas caused by lactose or How is gas treated? fiber. Gas can be treated by reducing swallowed • Simethicone (Gas-X, Mylanta Gas) can air, making dietary changes, or taking over- relieve bloating and abdominal pain or the-counter or prescription . discomfort caused by gas. People who think they have too much gas can • Lactase tablets or drops can help people try to treat gas on their own before seeing a with lactose intolerance digest milk and health care provider. Health care providers milk products to reduce gas. Lactase can provide advice about reducing gas and tablets are taken just before eating prescribe medications that may help. foods that contain lactose; lactase drops Reducing swallowed air. Swallowing less air can be added to liquid milk products. may help reduce gas, especially for people Lactose-free and lactose-reduced milk who burp frequently. A health care provider and milk products are available at most may suggest eating more slowly, avoiding grocery stores. gum and hard candies, or checking with a Taking prescription medications. Health dentist to make sure dentures fit correctly. care providers may prescribe medications to Making dietary changes. People may be able help reduce symptoms, especially for people to reduce gas by eating less of the foods that with small intestinal bacterial overgrowth or cause gas. However, many healthy foods may IBS. For more information about IBS, see cause gas, such as fruits and vegetables, whole the Irritable Bowel Syndrome fact sheet from grains, and milk products. The amount of gas the National Digestive Diseases Information caused by certain foods varies from person to Clearinghouse at www.digestive.niddk.nih.gov. person. Effective dietary changes depend on learning through trial and error which foods Eating, Diet, and cause a person to have gas and how much of People’s eating habits and diet affect the the offending foods one can handle. amount of gas they have. For example, While does not cause gas, limiting high- eating and drinking too fast may increase fat foods can help reduce bloating and the amount of air swallowed, and foods discomfort. Less fat in the diet helps the that contain carbohydrates may cause some stomach empty faster, allowing gases to move people to have more gas. more quickly into the small intestine. Tracking eating habits and symptoms can Taking over-the-counter medications. Some help identify the foods that cause more gas. over-the-counter medications can help reduce Avoiding or eating less of these foods may gas or the symptoms associated with gas: help reduce gas symptoms. • Alpha-galactosidase (Beano), an over- the-counter digestive aid, contains the sugar-digesting enzyme that the body

4 Gas in the Digestive Tract IBS. Self Administered Cognitive Behavior Therapy for Irritable Bowel Syndrome, Points to Remember funded under NIH clinical trial number • Gas is air in the digestive tract. NCT00738920, assesses the short- and • Everyone has gas. However, many long-term efficacy of cognitive behavior people think they pass gas too therapy for IBS using two treatment delivery often and that they have too much systems: self administered and therapist gas. Having too much gas is rare. administered. Long-term project goals include development of an effective self- • Gas in the digestive tract is usually administered behavioral treatment program caused by swallowing air and by the that can enhance quality of patient care, breakdown of certain foods in the improve clinical outcomes, and decrease the large intestine by bacteria. economic and personal costs of IBS. • Most foods that contain Safety Study of in Adults with carbohydrates can cause gas. In Irritable Bowel Syndrome, funded under contrast, fats and proteins cause NIH clinical trial number NCT00971711, is a little gas. phase I study of the safety and effectiveness • Foods that produce gas in one of VSL#3 in adults with IBS. VSL#3 is a person may not cause gas for high-potency medical food that someone else. is commercially available. Acupuncture/ Moxibustion for Irritable Bowel Syndrome • The most common symptoms (Acu/MoxalIBS), funded under NIH of gas are burping, passing gas, clinical trial number NCT00945074, tests bloating, and abdominal pain or the efficacy of acupuncture in combination discomfort. with moxibustion for symptom improvement • Gas can be treated by reducing in adults with IBS. Moxibustion is the swallowed air, making dietary application of heat from a burning herb at changes, or taking over-the-counter the acupuncture point. All participants will or prescription medications. receive moxibustion and will be assigned to one of three treatment protocols: standard acupuncture, individualized acupuncture, and sham acupuncture. Hope through Research Participants in clinical trials can play a more The National Institute of Diabetes and active role in their own health care, gain Digestive and Diseases (NIDDK) access to new research treatments before sponsors research into digestive conditions, they are widely available, and help others including gas. Researchers are studying by contributing to medical research. For disorders that may cause gas symptoms, such information about current studies, visit as IBS. www.ClinicalTrials.gov. The NIDDK and other components of the National Institutes of Health (NIH) are conducting clinical trials aimed at improving the diagnosis and treatment of

5 Gas in the Digestive Tract For More Information National Digestive Diseases Academy of Nutrition and Dietetics Information Clearinghouse 120 South Riverside Plaza, Suite 2000 2 Information Way Chicago, IL 60606–6995 Bethesda, MD 20892–3570 Internet: www.eatright.org (Click on “Find a Phone: 1–800–891–5389 Registered Dietitian”) TTY: 1–866–569–1162 International Foundation for Functional Fax: 703–738–4929 Gastrointestinal Disorders Email: [email protected] P.O. Box 170864 Internet: www.digestive.niddk.nih.gov Milwaukee, WI 53217–8076 The National Digestive Diseases Information Phone: 1–888–964–2001 or 414–964–1799 Clearinghouse (NDDIC) is a service of the Fax: 414–964–7176 National Institute of Diabetes and Digestive Email: [email protected] and Kidney Diseases (NIDDK). The Internet: www.iffgd.org NIDDK is part of the National Institutes of Health of the U.S. Department of Health Acknowledgments and Human Services. Established in 1980, Publications produced by the Clearinghouse the Clearinghouse provides information are carefully reviewed by both NIDDK about digestive diseases to people with scientists and outside experts. This digestive disorders and to their families, publication was reviewed by Brooks D. Cash, health care professionals, and the public. M.D., F.A.C.P., F.A.C.G., National Naval The NDDIC answers inquiries, develops and Medical Center. distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate You may also find additional information about this resources about digestive diseases. topic by visiting MedlinePlus at www.medlineplus.gov. This publication may contain information about medications. When prepared, this publication This publication is not copyrighted. The Clearinghouse included the most current information available. encourages users of this publication to duplicate and For updates or for questions about any medications, distribute as many copies as desired. contact the U.S. Food and Administration toll- free at 1–888–INFO–FDA (1–888–463–6332) or visit This publication is available at www.fda.gov. Consult your health care provider for www.digestive.niddk.nih.gov. more information.

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NIH Publication No. 13–883 November 2012

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