Technical University of Denmark (DTU)
The time it takes for ingested food to travel through the human
gut – also called transit time – affects the amount of harmful degradation
products produced along the way.
This means that transit time is a key factor in a healthy
digestive system. This is the finding of a study from the National Food
Institute, Technical University of Denmark, which has been published in the
renowned journal Nature Microbiology.
Food has to travel through eight meters [over26 feet] of intestine from the time it enters the mouth of an
adult person until it comes out the other end. Recent research has focused
mainly on the influence of the bacterial composition of the gut on the health
of people’s digestive system.
Taking this a step further, Postdoc Henrik Munch Roager from the
National Food Institute has studied how food’s transit time through the colon
affects gut bacteria’s role in the activity and health of the digestive system
by measuring the products of bacterial activity, which end up in urine.
The effect of food’s
transit time
Intestinal bacteria prefer to digest dietary carbohydrates, but
when these are depleted, the bacteria start to break down other nutrients such
as proteins. Researchers have previously observed correlations between some of
the bacterial protein degradation products that are produced in the colon and
the development of various diseases including colorectal cancer, chronic renal
disease and autism.
“In short, our study shows that the longer food takes to pass
through the colon, the more harmful bacterial degradation products are
produced. Conversely, when the transit time is shorter, we find a higher amount
of the substances that are produced when the colon renews its inner surface,
which may be a sign of a healthier intestinal wall,” Henrik’s supervisor and
professor at the National Food Institute, Tine Rask Licht, explains.
It is commonly thought that a very diverse bacterial population
in the gut is most healthy, however both the study from the National Food
Institute and other brand news studies show that bacterial richness in stool is
also often associated with a long transit time.
”We believe that a rich bacterial composition in the gut is not
necessarily synonymous with a healthy digestive system, if it is an indication
that food takes a long time to travel through the colon,” Tine Rask Licht says.
Better understanding of
constipation as a risk factor
The study shows that transit time is a key factor in the
activity of the intestinal bacteria and this emphasizes the importance of
preventing constipation, which may have an impact on health. This is highly
relevant in Denmark where up to as much as 20% of the population suffers from
constipation from time to time.
The National Food Institute’s findings can help researchers
better understand diseases where constipation is considered a risk factor, such
as colorectal cancer and Parkinson’s disease as well as afflictions where
constipation often occurs such as ADHD and autism.
Influencing food’s transit
time
Tine Rask Licht emphasizes that people’s dietary habits can
influence transit time:
”You can help food pass through the colon by eating a diet rich
in fibre and drinking plenty of water. It may also be worth trying to limit the
intake of for example meat, which slows down the transit time and provides the
gut bacteria with lots of protein to digest. Physical activity can also reduce
the time it takes for food to travel through the colon.”