Digestibility of Selected Resistant Starches in Humans

Dietary fiber is a type of carbohydrate which is not digested in the human small intestine. Whole grains are a source of dietary fiber that are used to promote health; however, using whole grains in commercial products results in a different taste and/or texture than the usual products made from refined grains. Thus, other types of high-fiber ingredients have been developed which can be incorporated into food products with less effect on their taste and/or texture. An example of this is resistant starch, defined as starch which is not digested in the human small intestine. The digestibility of starch is usually determined in-vitro; however, there is evidence that such methods may overestimate the amount of resistant starch by as much as 100%. The measurement of the amount of carbohydrate in the ileal effluent, digestive waste, of subjects with an ileostomy is considered to be the best in-vivo method of starch digestibility. The subjects collect ileal effluent during the day during which time they consume a polysaccharide-free diet. There is evidence that resistant starch consumed at breakfast is completely recovered in ileal effluent 8-10hr after consumption. The purpose of this study will be to compare the carbohydrate content recovered in ileal effluent of 10 subjects with a conventional ileostomy.

Study Overview

• Status: Completed
• Conditions: Ileostomy - Stoma; Malabsorption; Carbohydrate
• Intervention / Treatment: Other: Starch-free breakfast; Other: Hi-Maize 260; Other: Hylon VII; Other: Amioca

Detailed Description

Dietary fiber consists mainly of carbohydrates which are not digested in the human small intestine. A high intake of dietary fiber is associated with many health benefits including, but not limited to, improved bowel function and reduced risk of weight gain, cardiovascular disease and diabetes. Therefore, there is great interest in the food industry to produce products enriched with dietary fiber to promote health. One way to achieve this is to use more whole grains (wheat, rice, oats, barley) as ingredients in products such as breakfast cereals, breads and food bars. However, the use of whole grains results in products which have a different taste and/or texture than the usual products made from refined grains. Thus, other types of high-fiber ingredients have been developed which can be incorporated into food products with less effect on their taste and/or texture. Examples of such ingredients are inulin (an oligosaccharide containing fructose) and resistant starch. Resistant starch, defined as starch which is not digested in the human small intestine, is present in small amounts (2-5% of total starch) in many normal foods.

Starch is the most abundant energy containing nutrient in the human diet; it consists of 2 types of polysaccharides: amylose, is a linear polymer consisting of long chains of glucose molecules joined by 1-4 linkages; and amylopectin, a highly branched polymer consisting of long chains of glucose molecules joined by 1-4 linkages with numerous 1-6 linkage branch points. Most (70-80%) of the starch in normal starchy foods (eg. cereals and potatoes) is amylopectin. Amylopectin is highly digestible because its branched structure makes it readily able to gelatinize, the process whereby adjacent starch molecules swell and separate from each other under the influence of moist heat (ie. cooking). By contrast amylose is less digestible because its linear structure allows adjacent molecules to associate by hydrogen bonding which reduces their ability to gelatinize. Some types of commercially available resistant starch come from strains of corn which produce starch containing 70 to 100% amylose.

The digestibility of starch is usually determined in-vitro using methods involving digestion of the starch with α-amylase under pH and temperature conditions thought to mimick digestion in the human small intestine. However, there is evidence that such methods may overestimate the amount of resistant starch by as much as 100%. Methods used to estimate starch digestibility in-vivo include the breath hydrogen method and the measurement of the amount of carbohydrate in the ileal effluent of subjects with an ileostomy. The latter is considered to be the best in-vivo method which involves preparation of subjects with a polysaccharide-free diet the day before then consumption of the test carbohydrate with breakfast. Subjects collect ileal effluent during the day during which time they consume a polysaccharide-free diet. There is evidence that resistant starch consumed at breakfast is completely recovered in ileal effluent 8-10hr after consumption. The objective of this study is to determine the amount of carbohydrates in 3 commercially available starches (Hi-Maize® 260, Hylon® VII and Amioca corn starch) which escape digestion in the human small intestine.

• Study Type: Interventional
• Enrollment (Actual): 3
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Canada
  • Ontario
    • Toronto, Ontario, Canada, M5C 2N8
      • Glycemic Index Laboratories, Inc.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 75 years (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• males or non-pregnant females with a conventional ileostomy
• clinically stable with no clinical evidence of malabsorption

Exclusion Criteria:

• short bowel syndrome
• acute exacerbation of inflammatory bowel disease
• prone to high output with change in diet
• ileostomy created less than 6 months from the first study visit
• subjects using medications which influence gastrointestinal motility or absorption
• any condition which might, in the opinion of Dr. Wolever or Dr. Kim either: 1) make participation dangerous to the subject or to others, or 2) affect the results
• subjects who cannot or will not comply with the experimental procedures
• food allergies of any kind

Study Plan

How is the study designed?

Design Details

• Allocation: NA
• Interventional Model: SINGLE_GROUP
• Masking: NONE

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: All subjects; All subjects will undergo all 4 treatments, starch-free breakfast, Hi-Maize 260, Hylon VII and Amioca in randomized order	Other: Starch-free breakfast; Starch-free breakfast alone; Other: Hi-Maize 260; Starch-free breakfast plus 55.3g Hi-Maize 260; Other: Hylon VII; Starch-free breakfast plus 56.9g Hylon VII; Other: Amioca; Starch-free breakfast plus 56.4g amioca starch

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Amount of carbohydrate in ileostomy effluent	Carbohydrate in ileal effluent will be measured using by proximate analysis and expressed in grams.	Up to 10 hours after starting to consume breakfast

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Amount of fiber in ileostomy effluent	Fiber is measured using the Englyst method and expressed in grams.	Up to 10 hours after starting to consume breakfast
Amount of starch in ileostomy effluent	Starch will be measured using the Megazyme assay and expressed in grams.	Up to 10 hours after starting to consume breakfast

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Amount of fiber in ileostomy effluent	Fiber will be measured using fiber assay 2009.01 and expressed in grams.	Up to 10 hours after starting to consume breakfast
Amount of fiber in ileostomy effluent	Fiber will be measured using fiber assay 991.43 and expressed in grams.	Up to 10 hours after starting to consume breakfast
Amount of starch in ileostomy effluent	Starch will be measured by acid hydrolysis and expressed in grams.	Up to 10 hours after starting to consume breakfast

Collaborators and Investigators

• Sponsor: Unity Health Toronto
• Collaborators: University of Toronto; Glycemic Index Laboratories, Inc; Iowa State University; Ingredion Incorporated
• Investigators: Principal Investigator: Thomas M. Wolever, MD, PhD, Unity Health Toronto

Study record dates

Study Major Dates

• Study Start: September 1, 2013
• Primary Completion (ACTUAL): December 1, 2013
• Study Completion (ACTUAL): August 1, 2014

Study Registration Dates

• First Submitted: August 29, 2013
• First Submitted That Met QC Criteria: September 5, 2013
• First Posted (ESTIMATE): September 11, 2013

Study Record Updates

• Last Update Posted (ESTIMATE): November 18, 2014
• Last Update Submitted That Met QC Criteria: November 17, 2014
• Last Verified: November 1, 2014

More Information

Terms related to this study

• Keywords: Ileostomy; Resistant starch; In vivo; Carbohydrate digestibility
• Additional Relevant MeSH Terms: Digestive System Diseases; Metabolic Diseases; Gastrointestinal Diseases; Intestinal Diseases; Malabsorption Syndromes
• Other Study ID Numbers: GIL-1322