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Colonic Microbial and Clinical Adaptation to Large Doses of Fructose

18 Years
40 Years
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Trial Information

Colonic Microbial and Clinical Adaptation to Large Doses of Fructose

The concept of Colonic Adaptation(CA) to regular carbohydrates has been linked mainly to
lactose disaccharide(galactose,glucose) and lactulose(galactose, fructose), a manufactured
derivative of lactose. CA is achieved in both cases by short term regular consumption of the
targeted sugar which is not digested by the host. The clinical definition of CA includes a
measured change in breath hydrogen, reduction of clinical symptoms (Bloat, gas, cramps and
at times diarrhea) and an associated increase of bacterial lactase(β-galactosidase. The
putative mechanism is through bacterial action which results in enhanced metabolism or
expanded bacterial population of specific genus and species of bacteria. The act of CA may
incur health benefits through physicochemical changes and especially promotion of health
promoting bacteria.

Maldigestion of fructose occurs in the population probably in a dose dependent fashion. The
sugar content overwhelms the principal GLUT5 intestinal carrier. In the presence of glucose
this non energy dependent system works better(11). In a previous publication we found that
the pre test graded ingestion of fructose had no impact on test results. These results were
dramatically different from that found for pretest lactose ingestion. The investigators
interpreted the results from the fructose study as being consistent with a failure to show
CA to regular fructose consumption.

More recently Rao et al however, showed that there may be a threshold level of intake beyond
which fructose maldigestion may rapidly increase. This value was thought to be 15-20g. In
the case of lactose this was 10g(15). Since in both our studies we used the same dose
response analysis(<10,11-19, and >20g/d), it is possible that fructose consuming individuals
might not have spilt adequate quantities of fructose into the colon to properly induce and
maintain CA. Moreover, there is to our knowledge no information on a possible prebiotic
effect of the monosaccharide fructose. Since polymers of fructose are very good prebiotics
it may be of interest to determine whether this sugar is capable of prebiotic function in
its own right.

The investigators propose to carry out a short term study on 20-30 healthy participants to
determine whether a 2 week period of fructose consumption alters clinical CA and intestinal

Study Outline After an overnight fast, except for water(ad libitum), participants present
themselves to the GI lab around 9 am. A 50 gm fructose solution (this dose is associated
with a 65% chance of maldigestion(14))will be administered. Breath hydrogen and symptoms
will be recorded for 4.5 Hrs at ½ hr intervals. Participants will be asked to fill out a
short 3 day diet recall questionnaire targeting fructose ingestion.

Participants will be asked to consume 30g fructose in 150ml of water (lemon juice may be
added) twice a day for 14 days.They will then return for a repeat50 g fructose challenge. A
small stool sample will be asked from participants at each test period.Another similar group
will undergo the same tests but without taking intervening fructose.

Inclusion Criteria:

- Healthy participants

Exclusion Criteria:

- Antibiotics 90 days pre entry

- Use of gastrointestinal motility drugs eg loperamide, metoclopramide significant
fiber supplements

- Pregnancy

Type of Study:


Study Design:

Allocation: Non-Randomized, Intervention Model: Crossover Assignment, Masking: Open Label, Primary Purpose: Basic Science

Outcome Measure:

Statistically significant reduction in total sum breath hydrogen upon a 50g fructose challenge test.

Outcome Time Frame:

intervention for 2 weeks per participant

Safety Issue:


Principal Investigator

Andrew Szilagyi, MD

Investigator Role:

Principal Investigator

Investigator Affiliation:

SMBD Jewish General Hospital, McGill university School of Medicine


Canada: Ethics Review Committee

Study ID:




Start Date:

January 2008

Completion Date:

December 2008

Related Keywords:

  • Healthy
  • Fructose
  • Intolerance
  • Adaptation
  • Prebiotic
  • Healthy men or women 18-40