The Relation of Passage of Gas and Abdominal Bloating to Colonic Gas Production

15 February 1996 | Volume 124 Issue 4 | Pages 422-424

Objective: To determine the relation of gas passage and abdominal bloating to the production of gas in the colon.

Design: Randomized, double-blind, crossover study of gaseous symptoms during a 1-week period.

Setting: A Veterans Affairs medical center.

Participants: 25 healthy medical center employees.

Intervention: Participants' diets were supplemented with either a placebo (10 g of lactulose, a nonabsorbable sugar), psyllium (a fermentable fiber), or methylcellulose (a nonfermentable fiber).

Measurements: All participants were polled for gaseous symptoms (including number of gas passages, impression of increased rectal gas, and abdominal bloating), and five were examined for breath hydrogen excretion.

Results: Participants passed gas 10 ± 5.0 times per day (mean ±SD) during the placebo period. A significant increase in gas passages (to 19 ± 12 times per day) and a subjective impression of increased rectal gas were reported with lactulose but not with either of the two fiber preparations. Breath hydrogen excretion, an indicator of hydrogen production in the colon, did not increase after ingestion of either of the fibers. However, a statistically significant (P < 0.05) increase in feelings of abdominal bloating (which the participants perceived as excessive gas in the bowel) was reported with both fiber preparations and with lactulose.

Conclusions: The physician should distinguish between excessive rectal gas (which indicates excessive gas production) and feelings of bloating (which are usually unrelated to excessive gas production). Treatment of the former consists of limiting the supply of fermentable material to the colonic bacteria. Symptoms of bloating usually indicate the irritable bowel syndrome, and therapy should be directed accordingly.

Author and Article Information

From the Veterans Affairs Medical Center, Minneapolis, Minnesota.
Grant Support: In part by the Department of Veterans Affairs, National Institute of Diabetes and Digestive and Kidney Diseases RO1 DK 13309-25, and Procter & Gamble Co., Cincinnati, Ohio.
Requests for Reprints: Michael D. Levitt, MD, Veterans Affairs Medical Center, Research Service (151), One Veterans Drive, Minneapolis, MN 55417.
Current Author Addresses: Drs. Levitt, Furne, and Olsson: Veterans Affairs Medical Center, Research Service (151), One Veterans Drive, MInneapolis, MN 55417.