Fructose is a naturally occurring sugar found in many fruits. Food manufacturers commonly add fructose, usually in the form of high-fructose corn syrup, to a variety of products to enhance sweetness. The capacity of the small intestine to absorb fructose proves limited. People with a low tolerance for fructose or excessive dietary intake of the sugar commonly develop intestinal symptoms, a condition known as dietary fructose intolerance. Avoiding or limiting dietary intake of the sugar frequently leads to resolution of fructose intolerance symptoms.
Diarrhea
The presence of unabsorbed fructose leads to increased water in the small intestine. As the watery fecal material passes into the colon, it stimulates increased muscular activity of the large bowel, explain Dr. Peter Gibson and colleagues in a November 2006 review article published in the journal "Alimentary Pharmacology and Therapeutics." The colon normally absorbs most of the water in the fecal material received from the small intestine, yielding semi-solid stool. Rapid transit of fecal material through the colon associated with fructose intolerance limits the amount of colonic water absorption, leading to diarrhea.
Foods with a high fructose concentration that may lead to diarrhea and other intestinal symptoms in patients with a low tolerance for the sugar include pineapples, oranges, honey, pears, watermelon, apples, regular sodas and processed fruit juices and beverages containing high-fructose corn syrup.
Abdominal Bloating and Gas
Patients with dietary fructose intolerance, also known as fructose malabsorption, often experience abdominal bloating and increased intestinal gas, reports the Department of Food and Nutrition Services of the University of Iowa Hospitals and Clinics. Unabsorbed dietary fructose passes into the colon where bacteria digest the sugar, releasing hydrogen, methane and carbon dioxide gases.
Depending on the concentration of fructose in the bowel, the amount of gas produced may prove substantial, leading to abdominal bloating and frequent passing of intestinal gas. In an August 2007 article published in the journal "Clinical Gastroenterology and Hepatology," gastroenterologist Satish Rao, M.D., Ph.D., and colleagues report that 30 percent of healthy volunteers with laboratory evidence of incomplete fructose absorption after ingestion of 50 g of the sugar experienced increased intestinal gas. Ten to 15 percent also experienced abdominal bloating.
Abdominal Pain
Dietary fructose intolerance may lead to abdominal pain, reports the American Gastroenterological Association. In the 2007 Rao study, 10 to 15 percent of healthy volunteers with evidence of incomplete fructose absorption reported abdominal pain. Increased muscular activity of the colon and the presence of large volumes of intestinal gas prove likely causes of the abdominal pain associated with dietary fructose intolerance.
References
- "Alimentary Pharmacology and Therapeutics"; Fructose Malabsorption and the Bigger Picture; Peter R. Gibson, M.D., et al.; November 2006
- "Practical Gastroenterology"; Clinical Ramifications of Malabsorption of Fructose and Other Short-chain Carbohydrates; Jacqueline S. Barrett, B.Sc., M.N.D., Peter R. Gibson, M.D., Ph.D.; August 2007
- University of Iowa Hospitals and Clinics: Dietary Fructose Intolerance
- "Clinical Gastroenterology and Hepatology"; The Ability of the Normal Human Small Intestine to Absorb Fructose: Evaluation by Breath Testing; Satish S.C Rao, M.D., Ph.D., et al.; August 2007
- American Gastroenterological Association: Fructose Intolerance
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