US Pharm. 2009;34(12):16-22.
Patients often consider pharmacists as professionals to whom they can confide embarrassing medical problems in the hope that the pharmacist will provide some assistance. One such problem is abdominal bloating, often thought to be due to excess intestinal gas. However, patients may also experience abdominal discomfort they attribute to gas, but can be caused by several serious medical conditions.
Prevalence of Bloating and Gas
The prevalence of intestinal gas and bloating is unknown, as reliable large-scale studies do not exist. However, bloating and flatulence (defined as excessive air or other gas in the stomach and/or intestines) are two of the most common complaints for which patients seek medical care.1
Manifestations of Bloating and Gas
Bloating and gas can cause several complaints or coexist with them. Patients complain of excessive belching (eructation).2 Belching is a normal response during or after a meal, especially one that was eaten so rapidly that the patient also swallowed air. However, some patients swallow air intentionally to facilitate belching, a practice that can develop into an unconscious habit. Thus, if people burp excessively, they may be chronic air swallowers. Patients may deny that they swallow air as a nervous habit, forcing physicians to give them a mirror to observe the episodes themselves.
Flatulence is a common and logical consequence of intestinal gas. Average patients with no pathology or underlying medical condition produce 1 to 4 pints of intestinal gas per day and flatulate 14 to 23 times daily.2,3
Abdominal distention is an increase in abdominal girth that is frequently ascribed to excessive intestinal gas.2,4 This perception is often incorrect, as many such patients have normal amounts of gas. Rather, investigators believe that these patients have a heightened awareness of intestinal gas. Thus, even normal volumes of gas cause troublesome symptoms.
Abdominal pain is another complaint often thought to be due to gas.2,3 It may arise from either side of the colon, mimicking such conditions as heart disease, gallstones, and appendicitis.
Possible Causes of Bloating and Gas
Various sources of excess gas have been identified, including air swallowing, diet, lactose intolerance, and irritable bowel syndrome (IBS).
Aerophagia: Aerophagia, or air swallowing, has long been thought to be responsible for bloating and gas, as previously described.5,6 But there had been little evidence to support the hypothesis, as logical as it sounds. However, in 2009, investigators confirmed the hypothesis by assessing swallowing frequency in general and air swallowing frequency in particular in patients with suspected aerophagia.5 They identified a group of patients with typical complaints of bloating, abdominal distention, flatulence, and/or excessive belching. Abdominal x-rays confirmed the presence of excessive abdominal gas, the presumed source of the complaints. The researchers carried out 24-hour pH-impedance monitoring on subjects, discovering that swallowing frequency for the 24-hour period was normal (741 +/- 71 episodes), but the number of air swallows and gastric belches was excessive (521 +/- 63 and 126 +/-37, respectively). Thus, the advice presented in this month’s Patient Information section regarding air swallowing may be beneficial for these patients.
Diet: Diet is a major cause of bloating and gas. One of the most common dietary issues is eating foods that cannot be digested in the gastrointestinal (GI) tract due to a lack of the necessary enzymes.1,2
If certain food residues (mostly carbohydrates) reach the large intestine, normal bacterial residents utilize them as food sources, producing carbon dioxide, hydrogen, and sometimes methane as by-products.1,2 Exactly which foods cause gas varies from person to person. Some patients’ bowel microorganisms destroy hydrogen, lessening their intestinal gas burden.2 Nevertheless, some foods are universally identified as gas producers.
Carbohydrate-containing foods are among the most common culprits in causing intestinal gas, whereas fatty foods and proteins are seldom responsible.1,2,7Raffinose is one such complex sugar, being found in the indigestible seed coatings of beans, cabbage, brussels sprouts, broccoli, asparagus, other vegetables, and whole grains.2 Fructose is another offender, found in onions, artichokes, pears, and wheat; it is also used as an artificial sweetener. Sorbitol is also an artificial sweetener, but it is a naturally occurring component of apples, pears, peaches, and prunes. Sorbitol is a cause of “Halloween diarrhea,” a phenomenon experienced by many children who consume large amounts of candy on Halloween night. Numerous patients also report that psyllium ingested to ensure regularity causes gas (e.g., Metamucil, Konsyl). These patients may benefit by switching to methylcellulose, an FDA-approved fiber supplement that is not fermented by colonic bacteria (e.g., Citrucel).
Lactose Intolerance: Lactose intolerance (LI) is another type of carbohydrate malabsorption, discussed separately because of its different etiologies.1 Lactase found in the brush border cells of the small intestine is essential for breaking lactose down into its component sugars for absorption. Lactase deficiency is the underlying defect behind LI.
There are two major types of LI. They share the same consequences, in that undigested lactose reaches the intestinal tract, where the colonic microbiota digest it, producing gas, diarrhea, bloating, borborygmus, and a host of other complaints, beginning as early as 30 minutes after ingestion.8,9 The more common type of LI is the primary form, experienced by most of the world’s peoples, including those of African, Native American, and Asian heritage. In primary LI, lactase activity drops sharply after weaning from breast milk, until it is virtually absent. Drinking milk or ingesting dairy products causes the symptoms to begin.
Some people also suffer from secondary LI. They normally produce lactase as adults, but an environmental insult or surgical procedure compromises their ability to do so. Possible causes of secondary LI include chemotherapy, diarrheal diseases, small intestine resection, or celiac disease.1 Pharmacists can direct patients with suspected LI to lactase-containing supplements (e.g., Lactaid) or lactose-free dairy products.
Irritable Bowel Syndrome: IBS causes abdominal pain, cramping, bloating, constipation, and diarrhea.10-12 About 20% of Americans suffer from IBS, perhaps due to colonic hypersensitivity to specific foods or in response to stressful situations.11 Pharmacists should refer patients with suspected IBS to a physician for a full evaluation, but they can also advise patients to keep a food diary to help identify dietary causes of IBS. Elimination of certain foods and drinks (e.g., chocolate, alcohol, caffeine, cola, tea, peppers, onions) may be all that is needed to provide relief.
Pharmacists can recommend two types of nonprescription products other than lactose-intolerance products. One group of products contains simethicone, a nontoxic and hypoallergenic ingredient that is FDA approved as safe and effective in breaking down bubbles or froth in the GI tract, although the total amount of gas remains the same.1 Simethicone’s usefulness may be due to several factors. Some patients may experience abdominal discomfort as normal amounts of intestinal gas move through them. Reducing froth may allow the gas to pass through more readily. Further, patients using simethicone may be able to eliminate gas in several larger episodes, reducing the perception of excessive gas. Products with simethicone include Mylanta Gas, Phazyme, and Gas-X. The dosage is typically 1 or 2 units as needed after meals and at bedtime.
Alpha-galactosidase is another means to prevent bloating and gas.1,13 This is an enzyme derived from Aspergillus niger, and it has the ability to break down the oligosaccharide linkages that humans cannot digest. The patient is then able to absorb the single-component sugar residues. In research exploring the enzyme’s efficacy, subjects ingested two meals of meatless chili composed of several types of beans, cabbage, cauliflower, and onions.14 They were given either a placebo or the commercially available alpha-galactosidase product, known as Beano. Beano reduced the number of flatulence events at all times except for 2 hours postingestion. The effect was most pronounced 5 hours after the meal.14
To use Beano solution, the patient places approximately 5 drops on the first bite of troublesome food, such as beans, cabbage, cauliflower, broccoli, grains, cereals, nuts, seeds, and whole-grain breads.13 That amount usually covers a half-cup serving of food. If the meal consists of two or three servings of the food, the patient should place 10 to 15 drops on the meal. However, if the patient still experiences flatulence, the amount can be adjusted upward until an effective dose is reached. The patient may also swallow or chew a Beano tablet with the first bite of food or crumble it onto the first bite. One tablet usually digests a half-cup serving; more tablets can be used for larger portions. Patients cannot cook with Beano because of heat-induced enzyme degradation. Patients with galactosemia should consult a physician prior to use since enzymatic degradation of oligosaccharides produces galactose. Beano is labeled only for patients aged 12 years and above. While it appears to be safe during pregnancy and breastfeeding, there are no studies to confirm that observation. At one time, the manufacturer recommended that patients allergic to molds not use Beano, but the present view is that the caution is not supported by medical literature.13
Pharmacists can also advise patients to undergo an addition diet.15 With this method, the patient eliminates all foods and drinks that are thought to produce symptoms. If symptoms improve, the patient continues the diet for several days until reaching a perceived normal level, a state known as normoflatulence.15Then one new food or drink is added, and the patient records the results in a diary, paying particular attention to the intensity of the symptoms. Patients should discontinue any troublesome food for the duration of the addition diet and add another suspected food or drink after 48 hours. After several weeks of following this simple procedure, the patient begins to build a profile of difficult foods. Eventually all suspected foods will be identified, and the patient will have a much better idea of how to choose foods and drinks, even when visiting a restaurant.
When you swallow air, it must either be burped up or expelled as gas. Several problems can cause one to swallow air. Dentures that do not fit well cause you to swallow more saliva, which is mixed with air bubbles. If this is a possible cause, you should see the dental professional who fitted your dentures to have them adjusted. If you have postnasal discharge, you tend to swallow more than normal, allowing more air to enter your stomach. Judicious use of a nasal decongestant (e.g., Sudafed, Afrin) may help. Smoking cigarettes, cigars, or pipes and using chewing tobacco can increase salivation and contribute to excessive bloating, as can talking too much.
Some people belch excessively, either as a nervous habit or perhaps as a source of humor. To accomplish intentional belching, the person often first swallows air, followed by the belching. However, he or she seldom releases all of the swallowed air, and it becomes flatulence.
Eating too rapidly causes you to swallow extra air. You should slow your eating and chew the food thoroughly before swallowing it. Chewing gum and sucking on hard candy also increase the amount of swallowed air, so these practices should be reduced.
An easy way to help minimize bloating and gas is to focus on carbonated beverages (e.g., Coke, Pepsi). Manufacturers intentionally add carbonation to all of these sodas to give the products their “fizz.” When the bottle or can is agitated before being opened, everyone knows what the result will be—a great deal of bubbly drink on the floor. As a person drinks the beverage, the carbonation bubbles enter the stomach. If they are not belched out, they become excess flatulence. Many people could reduce gas problems dramatically by simply eliminating all carbonated beverages. If a person refuses to take this simple step, perhaps he or she can be convinced to allow the drinks to sit out on the counter at room temperature for several hours, which allows them to go flat and thus reduces the amount of swallowed gas.
The same advice can be given to beer drinkers. Beer contains gas, as indicated by the frothy head that develops when it is poured. You should completely eliminate it from your diet to see if your symptoms improve.
A major dietary cause of gas is beans, as well as other foods with indigestible components, such as cabbage, cauliflower, and broccoli. Your intestinal bacteria use these components as foods, producing gas as a by-product.
Lactose intolerance also contributes to gas and bloating. It is best to avoid dairy products or to take supplements that contain lactase, such as Lactaid.
Consult Your Pharmacist
There are several OTC products you can take to help relieve symptoms. Your pharmacist can assist you by advising on the use of simethicone (e.g., Gas-X, Mylanta Gas, Phazyme), which eases elimination of gas. Beano, a product that reduces the amount of gas, is a liquid solution that can be applied directly to food or taken as a tablet prior to eating
Remember, if you have questions, Consult Your Pharmacist.
1. Pray WS. Nonprescription Product Therapeutics. 2nd ed. Baltimore, MD: Lippincott Williams & Wilkins; 2006.
2. Gas in the digestive tract. NIDDK. http://digestive.niddk.nih.
gov/ddiseases/pubs/gas/. Accessed October 29, 2009.
3. Gas—flatulence. MedlinePlus. www.nlm.nih.gov/medlineplus/
ency/article/003124.htm. Accessed October 29. 2009.
4. Agrawal A, Whorwell PJ. Review article: abdominal bloating and distension in functional gastrointestinal disorders—epidemiology and explorations of possible mechanisms. Aliment Pharmacol Ther. 2008;27:2-10.
5. Hemmink GJ, Weusten BL, Bredenoord AJ, et al. Aerophagia: excessive air swallowing demonstrated by esophageal impedance monitoring. Clin Gastroenterol Hepatol. 2009;7:1127-1129.
6. Azpiroz F. Intestinal gas dynamics: mechanisms and clinical relevance. Gut. 2005;54:893-895.
7. Hernot DC, Boileau TW, Bauer LL, et al. In vitro fermentation profiles, gas production rates, and microbiota modulation as affected by certain fructans, galactooligosaccharides, and polydextrose. J Agric Food Chem. 2009;57:1354-1361.
8. Saulnier DM, Kolida S, Gibson GR. Microbiology of the human intestinal tract and approaches for its dietary modulation. Curr Pharm Des. 2009;15:1403-1414.
9. Ozdemir O, Mete E, Catal F, et al. Food intolerances and eosinophilic esophagitis in childhood. Dig Dis Sci. 2009;54:8-14.
10. Gasbarrini A, Lauritano EC, Garcovich M, et al. New insights into the pathophysiology of IBS: intestinal microflora, gas production and gut motility. Eur Rev Med Pharmacol Sci. 2008;12(suppl 1):111-117.
11. Irritable bowel syndrome. NIDDK. http://digestive.niddk.nih.
gov/ddiseases/pubs/ibs/. Accessed October 29, 2009.
12. Rana SV, Sharma S, Sinha SK, et al. Incidence of predominant methanogenic flora in irritable bowel syndrome patients and apparently healthy controls from North India. Dig Dis Sci. 2009;54:132-135.
13. Beano FAQs. GlaxoSmithKline. www.beanogas.com/FAQ.aspx. Accessed October 29, 2009.
14. Ganiats TG, Norcross WA, Halverson AL, et al. Does Beano prevent gas? A double-blind crossover study of oral alpha-galactosidase to treat dietary oligosaccharide intolerance. J Fam Pract. 1994;39:441-445.
15. Clearfield HR. Clinical intestinal gas syndromes. Prim Care. 1996;23:621-628.
16. Adolf Hitler had poor table manners and suffered flatulence. Telegraph. February 17, 2009. www.telegraph.co.uk/news/
flatulence.html. Accessed October 29, 2009.
To comment on this article, contact firstname.lastname@example.org.