FODMAP Reintroduction in Irritable Bowel Syndrome

The purpose of this study is to determine the amount and timing of when certain Fermentable
Oligo-Di-Monosaccharides and Polyols (FODMAPs), specifically fructose, can be safely
reintroduced into the diet of Irritable Bowel Syndrome (IBS) patients that have successfully
completed a low-FODMAP elimination diet. The FODMAP diet is an effective treatment for IBS;
however it is unclear how patients can successfully reintroduce and liberalize fructose into
their diet. The low FODMAP diet is thought to reduce IBS symptoms by decreasing water content
and gas production in the bowel and also possibly by altering gut bacteria. Although use of
the FODMAP elimination diet can initially successfully treat IBS symptoms for up to 50-75% of
patients, the reintroduction diet is difficult for patients to complete and maintain for long
periods of time because current methods for reintroduction of FODMAPs are imprecise leading
to frequent recurrent symptoms. As a result, patients often continue the low FODMAP
elimination diet for additional months because they have difficulties knowing how to add back
Protocol ID:IRB#16-000934 UCLA IRB Approved Approval Date: 2/22/2017 Through: 9/20/2017
Committee: Medical IRB 1 FODMAPs into their diet. There are no studies to date to help guide
patients with FODMAP reintroduction. For example, in the case of reintroducing fructose,
patients currently are currently instructed to add back honey into their diet over a 3-day
period using honey in 1- 3tsp doses (equivalent roughly to 2.86-8.6 grams of fructose).
However, honey is a sweetener made of both fructose and glucose and it is unclear whether
recurrent IBS symptoms are related to the concentration of fructose or the concentration of
fructose that is in relative excess to glucose. These types of confounding problems make it
difficult to generalize dietary reintroduction. The three study groups (i.e. fructose,
glucose, fructose/glucose) in this study are designed to determine if and how fructose leads
to recurrent IBS symptoms during the reintroduction diet. The fructose group will help to
determine whether an absolute amount of fructose will lead to IBS symptoms. Based on the
principals of the diet, we hypothesize IBS patients have lower thresholds for fructose
tolerance.

The glucose group will serve as a control since glucose is not a FODMAP and as a result is
not expected to lead to recurrent symptoms. The glucose/fructose mixture group is a cross
comparison group that will determine whether the relative excess fructose concentration is an
important cause of IBS symptoms. Fructose absorption in the gut is dependent on glucose
intake as fructose is transported with glucose from inside the gut into the body. Current
studies suggest that fructose intolerance in healthy controls is highly dependent on the
ratio of excess fructose to glucose.

The fructose/glucose treatment group is designed to investigate this potential relationship.