Cross-section of an intestine of
a 1-week-old piglet nourished with
total parenteral nutrition (TPN).
The TPN intestine is atrophied. (K9470-2)
The incompletely developed bodies of
premature infants suffer from a variety of gastrointestinal complications that
prevent doctors from feeding them in a normal fashion. To survive, they often
have to depend on parenteral nutrition—that is, direct infusion of
nutrients into the bloodstream that bypasses the intestinal tract.
Total parenteral nutrition (TPN) allows doctors to meet a premature infant's
nutritional requirements for growth and development when the infant's size or
condition makes enteral feeding—feeding by mouth—impossible.
Cross-section of a healthy,
newborn piglet intestine. (K9470-1)
Researchers at the
ARS Children's Nutrition Research Center
in Houston, Texas, led by Douglas G. Burrin, are trying to find out how much
feeding by mouth is needed to stimulate and normalize preemies' intestinal
growth. According to Burrin, use of TPN has drawbacks.
"One problem is that a lack of enteral feeding may lead to reduced growth
and functional development of the intestinal tract. In addition, premature
infants with short-bowel syndrome need enteral feeding for their intestines to
properly adapt and grow," says Burrin.
Doctors think they have found a way to deal with these concerns by giving
TPN-fed preemies small amounts of nutrition by mouth—referred to as
minimal enteral feeding. This feeding method increases the infants' tolerance
of full enteral feedings and speeds the maturation of gastrointestinal
motility, which is the ability of the intestines to move or contract.
Research suggests that certain nutrients actually stimulate intestinal growth
and maintain the mucosal lining in both adult and neonatal animals. "What
is not known is what the optimal levels or composition of nutrients are for
normal gastrointestinal growth and function," says Burrin.
Researchers used neonatal piglets to quantify the minimal amounts of enteral
nutrition necessary to stimulate and normalize growth of the small intestine.
They found that at least 40 percent of nutrients by mouth were necessary to
stimulate intestinal growth—and that 60 percent or more were needed to
normalize it. Previously, 5 to 10 percent were thought to be sufficient.
Neonatal piglets were used in the study because of the similarities between
their gastrointestinal development and function, body composition, and
metabolism and those of human neonatal infants.
The researchers are using this approach to determine whether specific nutrients
can be fed enterally to maximally stimulate intestinal growth and development.
Researchers are also studying how specific nutrients stimulate the secretion of
peptide hormones, which increase the intestinal absorption of nutrients.
The details of this study were recently published in the American Journal of
Clinical Nutrition.—By Jesús
García,Agricultural Research Service Information Staff.
This research is part of Human Nutrition, an ARS National Program (#107)
described on the World Wide Web at http://www.nps.ars.usda.gov.
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