Date:

January 17, 2018

Source:

University of Illinois College of Agricultural, Consumer
and Environmental Sciences

Summary:

Among
other benefits, breast milk contains natural sources of prebiotics: small,
indigestible fiber molecules that promote the growth of good bacteria in the
baby’s gut. Yet for many families, breastfeeding is difficult or impossible.
Fortunately, modern infant formulas are getting closer to the real thing with
the help of University of Illinois researchers.

Nearly every American who
has become a parent in the last decade has heard the slogan, “breast milk
is best,” and has likely been encouraged to offer breast milk to newborns.
Among other things, breast milk contains natural sources of prebiotics: small,
indigestible fiber molecules that promote the growth of good bacteria in the baby’s
gut. Yet for many families, breastfeeding is difficult or impossible.
Fortunately, modern infant formulas are getting closer to the real thing with
the help of University of Illinois researchers.

In a recent study from
the Piglet Nutrition and Cognition Lab at U of I, scientists worked with
piglets to show prebiotics included in infant formula can enhance memory and
exploratory behavior.

“When we provide
prebiotics in formula, our results confirm that we can not only benefit gut
health, which is known, but we can also influence brain development,” says
Ryan Dilger, associate professor in the Department of Animal Sciences, Division
of Nutritional Sciences, and Neuroscience Program at U of I. “We can
actually change the way piglets learn and remember by influencing bacteria in
the colon.”

Piglets are widely
considered a more informative model for human infants than mice and rats; their
digestive systems, behavioral responses, and brain development are remarkably
similar to human infants. Therefore, researchers are increasingly turning to
piglets to test hypotheses in pre-clinical trials related to human health,
especially in the context of gut microbes and brain development.

“There hasn’t been a
lot of work looking at the gut-brain axis in humans, but a lot of rodent work
is showing those connections. This is taking it to an animal model that is a
lot closer to human infants and asking if that connection still exists and if
we can tease out possible mechanisms,” says Stephen Fleming, lead author
of the study and a doctoral student in the Neuroscience Program at U of I.

In early 2016, Dilger and
his colleagues worked with piglets to show that a combination of innovative formula
components, including prebiotics, may play a role in brain development and
behavior. In their new study, the team concentrated solely on the effects of
prebiotics.

Starting on the second
day of life, piglets were given a cow’s milk-based infant formula supplemented
with polydextrose (PDX), a synthetic carbohydrate with prebiotic activity, and
galactooligosaccharide (GOS), a naturally occurring prebiotic. When the piglets
were 25 days old, Fleming took them through several learning, memory, and stress
tests. After 33 days, blood, brain, and intestinal tissues were collected for
analysis.

The test for learning and
memory gave piglets a chance to play with dog toys: one they’d seen before and
one brand-new toy. If they spent more time with the new toy, that was an
indication that the piglet recognized it as new and preferred it. This
“novel object recognition” test improves on classic maze tests
commonly used in rodent studies.

“If you’re trying to
test for memory, this test is closer to what we’d do with an infant. After all,
we don’t generally train infants on mazes,” Fleming says. “We know
from previous research this test works for pigs, but this is the first
published example of using it in a nutrition context.”

Pigs fed PDX and GOS
spent more time playing with new objects than pigs who didn’t receive the
prebiotic supplements. The preference for novel objects, an indication of
natural curiosity, is a sign of healthy brain development and points towards
positive development of learning and memory.

When prebiotics are
working the way they should, good bacteria increase in abundance. One way to
tell is by looking at metabolic end-products — volatile fatty acids (VFAs) —
excreted by bacteria during digestion of prebiotic fibers.

“Volatile fatty
acids are a global indicator for whether prebiotics had an effect on the
overall population of bacteria. For example, we might want to see an increase
in Lactobacillus and other beneficial bacteria that produce butyrate,”
Dilger explains. Volatile fatty acid (VFA) concentrations in the colon, blood,
and brain were changed in pigs receiving PDX and GOS compared with control
pigs.

Recent evidence suggests
that bacterial VFAs could be getting into the blood and traveling to the brain,
where they could potentially affect mood and behavior.

“We found that, yes,
VFAs are absorbed in the blood of pigs that were fed PDX/GOS. And, yes, they do
get into the brain,” Fleming explains. “But when we looked at the
relationship between these VFAs and the results of our behavior tests, there
did not appear to be a clear connection.”

Another surprise was a
decrease in serotonin in brains of pigs fed the prebiotic. “When you hear
less serotonin, there’s an immediate reaction to say, ‘Well, that’s bad,'”
Fleming says. Not necessarily; those pigs didn’t show greater anxiety than
control pigs during a stress test or poorer performance when given a learning
and memory test. The researchers hypothesize that the prebiotics may alter
levels of tryptophan, serotonin’s amino acid precursor, but it’s too early to
say.

Although more work is
needed to tackle remaining questions, the study adds to the growing body of
research suggesting a strong and potentially modifiable link between the gut
and the brain: a link that makers of infant formula should strongly consider.

“There are so many
ways we can alter the composition of the microbiota and they can have very
strong benefits. Promoting good ‘gut health’ remains a strong focus in the
field of nutrition,” Dilger says.

Story Source:

Materials provided by University of Illinois College of
Agricultural, Consumer and Environmental Sciences. Note:
Content may be edited for style and length.

Journal Reference:

1.    Stephen A. Fleming,
Supida Monaikul, Alexander J. Patsavas, Rosaline V. Waworuntu, Brian M. Berg,
Ryan N. Dilger. Dietary polydextrose and galactooligosaccharide increase
exploratory behavior, improve recognition memory, and alter neurochemistry in
the young pig. Nutritional Neuroscience, 2017