Impact of galacto-oligosaccharides on the intestinal microbial composition and -activity: a proof of concept study

The intestines contain large amounts of bacteria which contribute to well
functioning digestive system. Bacteria are involved in breakdown of nutrients,
but also in the immune system of the human body. Previous research has been
shown that dietary fibers are able to moduclate the composition of the
microbiota, especially in the large intestine, thereby inducing additional
health effects. In this study we will further investigate the effects of
galacto-oligosaccharides (GOS), a dietary fiber which is naturally present in
milk and for example is added to infant food.

We would like to investigate whether GOS benefically alters the microbiota
composition and -activity of the colon (not only faeces as done previously).
This has not been done before by performing colonoscopies in a physiological
condition and therefore highly relevant to compare with microbiota composition
and -activity in faeces. This information will gain more insights in the
working mechanism of this specific dietary fiber. In case study results will be
positive, this may lead to the development of more and new health promoting
foodproducts.

The study conforms to a randomized, double-blind and placebo-controlled design
including two parallel arms

Subjects will be randomized into one of the two groups. One group will receive
7.2 grams of GOS supplements tree times daily for four weeks. A second group
will receive 7.2 grams of placebo supplements three times daily for four weeks.

There are burdens volunteers can experience during this study.
- After the screening visit, participants will have to visit the Maastricht
University Medical Centre+ two times. In total, a participant will spend
approximately six hours at the university facility.
- They will have to take GOS or placebo products three times daily for a time
period of four weeks; the products used have been proven to be safe for human
use.
- During the two colonoscopies, colonic luminal content and biopsy specimens
will be collected, under sedation and after performing a standard enema. In
subjects undergoing colonoscopy there is a very small risk of bowel
perforation (0.0025%; report of the Gezondheidsraad). The risk of bleeding in
symptomatic patients undergoing colonoscopy for medical reason is 0.24%.
However, the risk of bleeding is associated with therapeutic interventions such
as polypectomy. In this study no therapeutic interventions will be performed.
The risk of complications is not increased when taking multiple biopsy
specimens.
- During both test visits subjects will be asked to arrive fasted. During the
same visits, body weight will be determind and subjects will bring a fecal
sample, which will be collected and frozen at home.
- Moreover, questionnaires will have to be filled out at several occasions
during this study. Besides we ask subjects to fill out a 3day food diary before
handing in the first fecal sample. When collecting fecal samples later in the
specific study period, we ask subjects to repeat the same food pattern and
record this again in a diary.