Sorbitol, a sweetener used in diabetic diets and present in jams, sweets and sugarless chewing gum, is also not digested in the small intestine and can give rise to flatus for the same reason as lactose. Certain medical conditions such as Crohn’s disease, celiac disease and other states of impaired absorption cause excess flatus because of impaired digestion. These conditions are associated with symptoms such as severe abdominal pains, weight loss, anemia and persistent diarrhea with pale smelly stools that tend to float in the toilet bowl. These symptoms require medical investigation.

Loud flatulence Loud flatulence is produced by powerful contractions of the bowel wall forcing gas out through a narrow anus—the muscle at the bottom of the rectum that keeps the intestinal contents in their place. There is not much you can do about this except grin and bear it, but measures to reduce flatus production may help.

Smelly flatulence Smelly flatulence is not your fault. It is caused by smelly substances such as indoles, skatoles and hydrogen sulphide that are produced by bacterial fermentation in the colon. Garlic and onions, many spices and some herbs of the fennel family that are used in Indian cooking produce smelly gases. Beer, white wine and fruit juices give rise to smelly hydrogen sulphide in some people. Worse still, some of these smelly gases are absorbed into the blood stream and excreted in the breath as well.

Further information
National Digestive Diseases Information Clearinghouse (NDDIC):

Last Reviewed: May 2013