Everyone has gas. Embarrassment sometimes prevents us from finding out what’s normal, what’s excessive, and what helps.
We all have it, and we all prefer not to talk about it. For one thing, gas is embarrassing: It departs 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 a problem such as irritable bowel syndrome.

The average adult releases intestinal gas 10–20 times a day, a total of one to three pints. 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 (see "Conditions associated with excess gas").

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.

Conditions associated with excess gas

• Celiac sprue (wheat gluten intolerance)
• Inflammatory bowel disease
• Irritable bowel syndrome
• Lactose intolerance
• Motility disorder
• Pancreatic enzyme insufficiency
• Intestinal obstruction
• Adhesions
• Infection
• Parasitic diseases

What is gas made of?
Most gas in the gastrointestinal system is made of odorless vapors, chiefly nitrogen, with the addition of oxygen, carbon dioxide, hydrogen, and methane. The exact composition varies depending on 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.

Swallowed air and burping
We all take in a bit of air with each swallow, whether we are eating, drinking, or swallowing saliva. We swallow more air if we eat too quickly, gulp down liquids, drink carbonated beverages, chew gum, smoke, or hyperventilate (for example, as a result of anxiety). Swallowed air can cause painful feelings of fullness or bloating that are relieved by burping, or belching, technically called eructation. Burping occurs when the upper esophageal sphincter relaxes and allows swallowed gas to rise up from the stomach and intestines into the esophagus and then to escape from the mouth. Normal burping is caused by air we swallow while eating and usually stops about an hour after the meal. Chronic burping (aerophagia) is caused by constant, unconscious air swallowing, often from anxiety. Air swallowed in this way usually makes a circuit within the esophagus and doesn’t go into the stomach.

Air that reaches the stomach seldom gets into the intestinal tract, although that’s more likely to happen if you are lying down. The stomach also releases carbon dioxide, but most of it is simply absorbed into the bloodstream.

What to do.
Remind yourself to eat and drink slowly (taking time to savor your food and drink may also pay off in lower calorie intake). Avoid chewing gum and drinking carbonated beverages. Be aware that certain foods—especially chocolate, fats, and peppermint—promote burping by relaxing the lower esophageal sphincter, where the esophagus joins the stomach. If you have persistent belching and simple measures don’t relieve it, you may want to see your clinician. If you feel a need to release stomach gas but can’t burp, try sucking on a peppermint lozenge. A small amount of baking soda in a glass of water may also help, although you shouldn’t take it on an overly full stomach.

Go ahead, eat beans
It’s no secret that beans can cause flatulence. But that’s no reason to avoid them. Beans—such as black beans, kidney beans, and pinto beans—are packed with nutrients, including protein, fiber, iron, B vitamins, potassium, and magnesium. They cost less than meat, have very little fat, and may reduce the risk for conditions such as heart disease, high blood pressure, and cancer.

If you start eating beans regularly, you may find that they produce less flatulence over time. Certain cooking methods also help. Bring dried beans to a boil in water (1 cup of beans to 10 cups of water) for 2 minutes; remove the pan from the heat, cover, and let it stand for an hour. Drain and add 3 cups of fresh water before cooking. You may also soak the beans overnight, then drain and add fresh water before cooking. Some food experts recommend changing the water more than once before cooking to remove even more of the volatile elements, although it’s possible this may drain away some of the nutrients.

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 fiber 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 sugar 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 dietetic candies and gums.

What to do.
If excess flatulence is a new symptom and accompanied by weight loss, diarrhea, lack of appetite, abdominal pain, or fever, see your clinician. Sometimes bloating and flatulence are the result of constipation and will go away once the constipation is treated. If all else seems well, the first step is to avoid foods that cause gas. This can be tricky; you don’t want to eliminate the fruits, vegetables, and whole grains that are the basis of a healthy diet.

Different foods affect different people differently, so you’ll need to figure out for yourself which ones give you the most trouble and how much of them you can tolerate. When flatulence is at its worst, write down all the foods you’ve eaten within the past 24 hours. If you do this each time, you may begin to home in on certain foods or food combinations. Then try eliminating the suspect food for a week and see what happens. Some people find that drastically reducing dietary sugars, refined starches, and wheat flour makes a difference.

Certain medications and over-the-counter products may help reduce or improve intestinal gas problems (see chart, "Products for preventing and treating flatulence," below).

Products for preventing and treating flatulence

Product	Effect
Alpha-galactosidase (Beano)	Breaks down gas-producing sugars in beans and other vegetables, reducing gas formation.
Activated charcoal pills*	May reduce gas formation and odor.
Digestive enzyme supplements	Breaks down carbohydrates, fats, and/or proteins, helping to reduce gas formation.
Lactase (Lactaid, Dairy Ease, Lactrase, others)	Helps digest foods that contain lactose.
Bismuth subsalicylate (Pepto-Bismol)	Reduces gas odor.
Charcoal-lined cushions and clothing pads	Absorbs gas odor.
Probiotics containing the bacterium L. plantarum**	May reduce flatulence in some people with irritable bowel syndrome.
* May interact with some prescription medications. ** Probiotics may also cause gas initially.