Intestinal gas is composed of varying quantities of exogenous sources (air that is ingested through the nose and mouth) and endogenous sources (gas produced within the digestive tract). The exogenous gases are swallowed (aerophagia) when eating or drinking or increased swallowing during times of excessive salivation.
In the large intestine, or colon, the gas volume is usually 100 to 200 cubic cm (6 to 12 cubic inches). Most of the oxygen has been removed, and the amount of carbon dioxide has increased. New gases formed from bacterial fermentation are added in the colon. Of the new gases produced, hydrogen is the major component. Some of this is absorbed by the blood and released through the lungs during breathing. Other gas products formed are methane, hydrogen sulfide, ammonia, and various sulfur-containing mercaptans.
Gas in the stomach contains approximately 15 to 16 percent oxygen and 5 to 9 percent carbon dioxide; the rest is nitrogen. The air that is breathed contains about 21 percent oxygen; thus, some of the swallowed oxygen is absorbed by the blood capillaries in the stomach. Carbon dioxide is formed by reduction of the food by the stomach’s gastric juices. Nitrogen is not absorbed as a gas and is usually passed on.
The Mayo Clinic suggests that you avoid the foods that cause your gas and acid symptoms and eat less fatty food because it slows digestion. They also suggest to temporarily cut back on your fiber intake to determine if it is causing problems. Fiber is important in your diet so experiment by adding it back slowly. Eat your food more slowly and take a walk after meals. Walking helps move gas through your system and eating more slowly reduces the amount of air you swallow with your food.
According to the experts at the National Digestive Diseases Information Clearinghouse, most people do believe that the amount of digestive gas they produce is extreme. Actually, it is normal to produce between one and four pints of abdominal gas per day. And, it is normal to pass gas about 14 times a day by either burping or passing gas through the rectum.
Foods that can cause excessive stomach gas and intestinal gas include beans, broccoli, cabbage, Brussels sprouts, onions, artichokes, and asparagus. Also, some fruits such as pears, apples, and peaches can have this effect. Other common culprits are dairy products and high-fiber foods such as bran and whole-grain breads, crackers, and cereals.
Sorbitol and mannitol are sugar alcohols that are poorly absorbed and are most likely to produce gas. “They are used in gram quantities to sweeten food, and when passed into the colon, they are fermented,” Schiller says. The artificial sweeteners saccharine and aspartame are so sweet that less has to be added to foods; they are used in milligram quantities. Since so little is ingested, they don’t produce gas and flatulence, Schiller explains.
For unknown reasons, abdominal bloating (swelling) after eating occurs more often in females. Bloating is usually caused by poor or disorganized contractions of the stomach and upper intestine. Relaxation of the abdominal muscles can also be a factor. Medications are now available that stimulate contractions in the stomach and upper intestine. These contractions move the food and fluid along, thereby reducing abdominal bloating.
Gas forming bacteria generally feed on certain carbohydrates and sugars. So, if these carbohydrates are reduced or eliminated from the diet, rectal gas can usually be significantly reduced. Individual response to certain foods is also a factor in producing rectal gas. For instance, two people can eat the same amount of the same carbohydrate. One forms large amounts of rectal gas, while the other experiences little or none.
The usual source of excessive gas is intestinal bacteria. The bacteria produce the gas (primarily hydrogen and/or methane) when they digest foods, primarily sugars and nondigestible polysaccharides (for example, starch, cellulose), that have not been digested during passage through the small intestine. The bacteria also produce carbon dioxide, but the carbon dioxide is so rapidly absorbed from the intestine that very little passes in flatus.
Flatulence is triggered by too much air within the digestive tract. Any annoyances within the stomach or digestive structure can consequence to flatulence. Flatulence is a main indication of acid reflux, but it is also triggered by gulping down excessive air while eating, talking at the same time eating and consuming foods that create gas.