Everyone gets gas. It's normal to pass gas about 14 times a day. Gas is produced during digestion and when bacteria in the intestines ferment undigested starch, sugar or fiber. Excessive gas can be due to lack of digestive enzymes or malabsorption of foods. Everyone reacts differently to different foods. Sometimes enzyme supplements can help, but often people must eliminate or decrease gas causing foods to decrease gas production.
Sugars
Sugars are easily fermented and are a big gas-producing culprit. One well known sugar is lactase, the sugar in dairy products. People that don't have enough lactase are considered lactose-intolerant. Lactose is also found in other dairy products, such as milk, cheese and ice cream and some breads, cereal, and salad dressing. Yogurt can usually be consumed without discomfort because it contains bacteria that naturally produce the lactase enzyme.
Beans contain large amounts of raffinose, a complex sugar that is difficult to digest. Other vegetables such as cabbage, broccoli and brussel sprouts contain smaller amounts. Raffinose can also be found in whole grains.
Fructose is sugar present in onions, artichokes, pears, apples, grapes, honey, wheat and some sweetened beverages. According to a study in October 2005 by the Department of Dietetics and Nutrition at the University of Kansas Medical Center, people don't efficiently absorb fructose. Residual fructose is fermented in the intestines and releases hydrogen gas.
Sorbitol is found naturally in fruits, including apples, pears, plums, and peaches. It is also an artificial sweetener in sugar-free candies, gums and other diet foods. In January 1988, the University of Bologna in Italy reviewed studies on sorbitol and reported that the poorly absorbed sugar was an underestimated cause of gastrointestinal distress.
Starches
Starches like potatoes, corn, pasta, and wheat produce gas because they are not digested well and the residue remains to be fermented. Rice does not cause gas.
Fibers
Some fibers are easily fermented by bacteria in the colon and produce gas. Fermentable fibers include oats, fruits, vegetables and barley. Wheat bran is a non-fermentable fiber that is high in cellulose. Wheat bran causes gas because it slows intestinal transit allowing other foods to ferment longer.
Beverages
Carbonated beverages like sodas or beer contain carbon dioxide. The carbon dioxide gas is released during digestion causing gas and bloating. Additionally, sweetened sodas contain fructose, a known gas producer.
