Intestinal gas: The right of passage

We all have it, and we all prefer not to talk about it. For one thing, gas is embarrassing: It leaves the body, often audibly, through burps and flatulence. In certain circumstances, it produces tortured-sounding bowel noises called borborygmi. Gas can also be uncomfortable, causing abdominal pain and bloating — symptoms that may appear on their own or in conjunction with another medical problem.

The average adult releases a total of one to three pints of intestinal gas a day. Many people who complain of excessive gas actually have normal amounts of it; it’s just that some people are more sensitive to its presence or less tolerant of its effects. Excessive gas rarely signifies anything serious, although a physician may want to investigate certain conditions that can cause it. These include celiac sprue (wheat gluten intolerance), inflammatory bowel disease, irritable bowel syndrome, lactose intolerance, motility disorder, pancreatic enzyme insufficiency, intestinal obstruction, adhesions, infection, and parasitic diseases. The two main sources of gassiness are swallowed air and the production of gas during the breakdown of food in the intestine. Gas-related symptoms depend partly on how fast the gastrointestinal system moves. You can reduce the symptoms by changing your diet, but it may require some compromises because some of the healthiest foods are the biggest gas producers. There are also products available that may help reduce gas problems.

What is gas made of?

Most gases in the gastrointestinal system are made of odorless vapors, chiefly nitrogen, with the addition of oxygen, carbon dioxide, hydrogen, and methane. The exact composition varies depending on the location. For example, the stomach has the same proportion of nitrogen and oxygen as the atmosphere — not surprising, since swallowed air is the major source of stomach gas — while gas produced in the intestine and expelled as flatus contains less oxygen and more methane. The unpleasant smell of intestinal gas comes from traces of sulfur-containing compounds produced by bacteria that live in the large intestine and break down foods, especially carbohydrates, that aren’t fully digested by enzymes in the small intestine.

Flatulence: The Gas We Pass

Most of the gas we expel is flatus, that is, gas produced in the intestine and released through the anus. Gases originating in the lower bowel — carbon dioxide, hydrogen, and methane — come from harmless resident bacteria that dine on foods not fully broken down by enzymes in the upper intestinal tract. Most such foods are carbohydrates, which include sugars, starches, and fiber. One major gas-producer is raffinose, a complex sugar found in vegetables such as cabbage, brussels sprouts, asparagus, broccoli, and some whole grains. Other troublemakers are starches and fibers in potatoes, corn, noodles, wheat, oat bran, peas, beans, and most fruits. (Rice is the only starch that doesn’t create gas.) Eggs, fish, chicken, and most meats produce little gas.

People who can’t digest lactose, the natural enzyme found in milk products, develop gas and bloating when they eat lactose-containing foods; the gas comes from incompletely digested lactose that’s broken down in the colon by gas-producing bacteria. Some people can’t tolerate fructose, which is found in onions, artichokes, fruits, and many commercial drinks. Another possible culprit is sorbitol, a sugar found naturally in fruits such as apples, pears, peaches, and prunes, and used as an artificial sweetener in diabetic candies and gums.

12 Tips For Dealing With Flatulence

Earlier this year, the American College of Gastroenterology put out a helpful list of 10 tips on dealing with intestinal gas. We did some of our own research, made some additions, and ended up with an even dozen.

1) It’s normal — and maybe a good sign. Most adults release gas 10 to 20 times a day. Some of the most healthy foods — beans, broccoli, some whole grains — tend to cause gas. A little bit of extra flatulence could be an indication that you’re eating the way you should.

2) Slow down, you’re eating too fast, you’ve got to make the mealtime last. Whenever you eat and drink something, a little bit of air goes down with it. Some of the air beats a hasty retreat in the form of a burp, but some may also get into the stomach and eventually make their way through the entire digestive tract. Much of the advice about reducing flatulence aims to reduce the amount of this incidental air intake: Eat and drink slowly and chew food thoroughly.

3) Airy now, pay later. Air also gets into the gut if it’s incorporated into food and drinks. Beer, soda, and other carbonated beverages are prime culprits. The gastroenterologists’ tips also warn about air-filled milk shakes, sponge cake, and soufflé.

4) Smoking: What doesn’t it cause? Apparently, some air gets swallowed when people smoke. Anti-smoking campaigns have tried to scare people with dire warnings about heart and lung disease. Maybe flatulence should be added to the list of consequences.

5) Avoid the brimstone. Flatus contains a mixture of gases, but the bad smell comes from the ones that contain sulfur, chiefly hydrogen sulfide and methylmercaptan. Putting less sulfur into your system can reduce the amount that comes out. Foods with notable sulfur content include eggs, meat, and cauliflower.

6) Beans and some vegetables can be trouble. There’s a trio of larger sugars — raffinose, stachylose, and verbascose — that manage to arrive in our colons relatively unscathed because we lack the enzymes to digest them. The reprieve doesn’t last long though. Bacterial residents of the colon feed on these sugars, producing gas as a by-product. Beans, lentils, other legumes, and some vegetables cause flatulence because they contain these sugars. Beans won’t produce as much gas if you boil them briefly, let them sit for an hour in the water, and then cook them again in a fresh pot of water. Just cooking them longer may also do the trick.

7) But Beano may help a little. Beano is a brand name for a non-prescription pill that contains alphagalactosidase, an enzyme that breaks down the digestible sugars before they can reach the colon. An Italian study published in 2006 found that a very high dose (the equivalent of eight regular Beano pills) reduced flatulence, but a more normal dose (two Beano pills) didn’t reach statistical significance. Still, Beano is worth a try.

8) Not so sweet in the end. Foods sweetened with high-fructose corn syrup can cause bloating and flatulence in some people because their small intestines can’t absorb large amounts of fructose. Sorbitol and the other sugar alcohols (maltitol, xylitol) can also be gas producers.

9) Remedies with question marks. Charcoal pills are supposed to absorb smelly sulfurous gases in the colon before they’re emitted as flatus, but study results have been inconsistent. Simethicone, the active ingredient in antigas products, works by dissolving gas bubbles. It’s been a mainstay gas medicine for years, but experts rate the benefit as questionable.

10) Odor-eating underwear. They’re the opposite of the whoopee cushion: seat cushions with charcoal filters that are supposed to absorb flatus. Michael Leavitt, MD, a Minneapolis researcher famous for his flatulence research, reported results comparing the cushions with other products made with odor-eating materials. Underwear made with an activated carbon fiber absorbed nearly all the sulfur-containing gases; pads worn inside the underwear, 55 to 77 percent of it; and the cushions, only 20 percent. The underwear is expensive, though: the brand that Leavitt used in his experiments costs US$65.

11) Adjusting the ecosystem. The bacteria in the intestines operate as a little ecosystem. Too few or too much of a particular species can produce excessive flatulence. Taking probiotics, which restock the gut with bacteria, can help. Sometimes, the problem is too much bacteria. Refaximin, an antibiotic used primarily to treat traveler’s diarrhea, is also sometimes prescribed for gut problems, including excessive flatulence.

12) Walking away from the problem. A Spanish study published in 2006 showed that study subjects retained less gas in their gut if they gently exercised (pedaling while on their backs so they would be as close as possible to a resting position). Of course, this means more flatulence, not less. But if you’re outdoors or in an open space, no one may notice — and you’ll feel a whole lot more comfortable!