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Investigation of Dietary Absorptive Capacity of Fructans in Healthy Subjects - A Dose Response Study

The recruitment status of this study is unknown. The completion date has passed and the status has not been verified in more than two years.
Verified March 2011 by University of Iowa.
Recruitment status was:  Active, not recruiting
American Gastroenterological Association Foundation
Information provided by:
University of Iowa Identifier:
First received: September 22, 2009
Last updated: March 7, 2011
Last verified: March 2011

Fructan is a carbohydrate polymer that is composed of fructose and a terminal glucose moiety . Fructans are naturally found in artichokes (6.1 grams/serving), leeks (5.9 grams/serving), onion bulbs (1.01 grams/serving), flour (4.0 grams/serving), garlic (.52 grams/serving), watermelon (.92 grams/serving), nectarines (.27 grams/serving) and white peaches (.50 grams/serving). Because fructans are present in many common foods, people typically ingest high levels of fructan. The most common structural forms of fructan are inulin, levanare and geraminan . The human body absorbs only 5% of fructan, however it is estimated that the daily intake in the USA may vary between 1-20 grams, and possibly higher due to the recently discovered benefits of inulins . Dietary trends indicate that high levels of fructans are common in the European and American diet, as more wheat based products such as breakfast cereal, pasta, and bread are consumed.

Fructans may not be well tolerated by some subjects and its malabsorption may result in gastrointestinal (GI) symptoms such as heartburn, belching, abdominal pain, diarrhea, gas, and bloating; and this is especially true when higher doses are ingested. Unlike glucose, fructans are not efficiently digested or absorbed by the small intestine. The mechanism for malabsorption is related to the inability to hydrolyze glycosidic linkages in the complex polysaccharide, resulting in the delivery of malabsorbed fructans to the large bowel1. In the colon, the malabsorbed fructans are rapidly fermented, and byproducts of this fermentation include H2, CH4, and other gases that may contribute to bowel symptoms. Furthermore, the small molecular nature of fructans results in an osmotic effect which draws more water into the small intestine and causes bloating and diarrhea.

Ingestion of high doses of fructans can cause symptoms in healthy adults, but may cause more bothersome symptoms in subjects with Irritable Bowel Syndrome (IBS). Earlier studies have identified that IBS affects between 10 and 15% of the population in the United States. Ingestion of 10-20 grams of fructan daily may cause symptoms of IBS, and restricting fructan intake in a diet may reduce symptoms in a variety of gastrointestinal disorders. One study recently published found that dietary restriction of fructan and fructose was responsible for symptomatic improvement in patients with IBS.


The investigators hypothesize that healthy individuals will absorb fructan 7.5 gram and 10 gram doses, and will experience malabsorption at the 12.5 gram fructan dose.

Condition Intervention Phase
Healthy Volunteers
Dietary Supplement: Fructan - 7.5
Dietary Supplement: Fructan - 10
Dietary Supplement: Fructan - 12.5
Dietary Supplement: Fructan -- 5 grams
Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double Blind (Participant, Care Provider, Investigator)
Primary Purpose: Treatment
Official Title: Investigation of Dietary Absorptive Capacity of Fructans in Healthy Subjects - A Randomized, Double-Blind Dose Response Study

Further study details as provided by University of Iowa:

Primary Outcome Measures:
  • Hydrogen and Methane Concentration levels [ Time Frame: 3 visits over a 1 month period ]

Secondary Outcome Measures:
  • Production of GI Symptoms [ Time Frame: 3 visits over a 1 month period ]
    Production of bothersome GI symptoms such as gas, bloating, cramping or abdominal pain during breath test. Symptoms were mesured using a validated symptom questionnaire.

Enrollment: 19
Study Start Date: June 2009
Estimated Study Completion Date: December 2010
Primary Completion Date: March 2010 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Fructan - 7.5
Subjects will consume 7.5 grams of fructan
Dietary Supplement: Fructan - 7.5
Subjects will consume 7.5 grams of fructan
Other Name: 7.5 grams of Inulin
Experimental: Fructan - 10 grams
Subjects will consume 10 grams of fructan
Dietary Supplement: Fructan - 10
Subjects will consume 10 grams of fructan
Other Name: 10 grams of Inulin
Experimental: Fructan - 12.5 grams
Subjects will consume 12.5 grams of fructan
Dietary Supplement: Fructan - 12.5
Subjects will consume 12.5 grams of fructan
Other Name: 12.5 grams of Inulin
Experimental: 5 grams Fructan

Experimental - 5 grams Fructan

Subjects will consume 5 grams of Fructan.

Dietary Supplement: Fructan -- 5 grams
Subjects will consume 5 grams fructan.
Other Name: 5 grams of Inulin


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Healthy volunteers between the ages of 18-70 years, with no previous history of gastrointestinal problems or any other ailments, no history of gastrointestinal surgery except appendectomy, cholecystectomy, caesarean section, hysterectomy and currently not using any medication except contraceptive pill, multivitamin, or aspirin.
  • They will be asked to fill out a Review of Systems health history (Appendix 2) and the Mayo Clinic Bowel Disease Questionnaire (Appendix 3) and will undergo a routine physical examination. Only patients who are asymptomatic and deemed healthy from the aforementioned screening procedure will be eligible.

Exclusion Criteria:

  • Currently taking medication for any ailment including OTC medication (excluding aspirin, multivitamins, and oral contraceptives)
  • History of gastrointestinal problems including bloating, gas, food intolerances or reflux symptoms
  • Any major abdominal surgery (except appendectomy, cholecystectomy, caesarean section, hysterectomy) or coexisting medical problem
  • Known food allergies
  • Prisoners
  • Cognitive Impairment or any other inability to provide informed consent
  Contacts and Locations
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Please refer to this study by its identifier: NCT00988403

United States, Iowa
University of Iowa Hospitals and Clinics
Iowa City, Iowa, United States, 52242
Sponsors and Collaborators
University of Iowa
American Gastroenterological Association Foundation
Principal Investigator: Satish Rao, MD, PhD University of Iowa
  More Information

Responsible Party: Satish SC Rao/Professor of Internal Medicine and Director of Neurogastroenterology and GI Motility, University of Iowa Identifier: NCT00988403     History of Changes
Other Study ID Numbers: Fructan
Study First Received: September 22, 2009
Last Updated: March 7, 2011

Additional relevant MeSH terms:
Antineoplastic Agents processed this record on April 25, 2017