The anatomical development of the human gut has been extensively studied and
is now well understood even at the ultrastructural level. However, the mechanisms
controlling gut development remain obscure.
Shortly after birth, infants start to consume milk, which is later replaced by a solid
diet. Qualitatively and quantitatively, several major differences exist between the
composition of the suckling's food, i.e., milk, and that of adults.
The mucosal immune system protects the most vulnerable surfaces of the body
(e.g., the gastrointestinal tract, lungs, and eyes) from the colonization and/or invasion
by pathogenic microorganisms.
Tarnier, the French obstetrician, developed an incubator for premature infant care
after seeing young chickens in an incubator at the Paris Zoo in 1878.
In order to appreciate how far the measurements of total body water can help in
evaluating the fluid requirements of preterm infants, it is interesting to examine the
evolution of whole body composition in absolute and relative terms and to compare
intrauterine to early postnatal values (Fig. 1).
At the moment of birth, the newborn infant is abruptly exposed to the thermal
environment of the delivery room and the body temperature immediately begins to
Utilization and storage of energy in growing very low birthweight (VLBW) preterm
infants can be studied using the concept of energy balance:
Fat digestion in the breastfed newborn infant is a process catalyzed by three Upases.
The process is initiated in stomach contents by gastric lipase and continues in the
upper part of the small intestine by pancreatic colipase-dependent lipase and human
milk bile-salt-stimulated lipase (BSSL).
Fat represents 40% to 50% of the total energy in breast milk and infant formulas.
In addition to being the major energy source, dietary fats are important qualitatively
because they supply essential fatty acids (EFA) crucial to normal growth of new
tissue membrane lipids.
Protein metabolism in human beings involves the breakdown of food protein into
peptides and amino acids, and the distribution of and use of the amino acids as
building blocks for protein molecules, as precursors for non-protein metabolites (e.g.,
neurotransmitters, purines and pyrimidines, creatinine, peptide hormones, etc.), or
as a source of energy.
It is a curious feature of mammalian life that fetal plasma and maternal plasma
are kept significantly different in composition. In woman (for whom a full range of
concentration differences are reported in ref. 1), the differences are most striking for
protein and peptide hormones, for which concentration differences may be as much
as four orders of magnitude.
Ninety-nine percent of the calcium and most of the phosphorus in the body is in
the skeleton; these elements and magnesium are also constituents of the intracellular
and extracellular spaces.
Optimization of transmission of nutrients from, and the return of wastes to, the
mother insures maximum fetal growth. Concentration gradient, molecular size, and
hydrophobicity of the solutes being transported are critical factors to be considered
in placental transfer processes.
During the past few years much attention has been paid to vitamin requirements
for very low birthweight (VLBW) infants and numerous original papers and review
articles, as well as guidelines and recommendations from official bodies, have appeared
in the literature (1-9).
The most widely accepted guideline for nutritional management of the low
birthweight (LBW) infant is to provide sufficient intakes of all nutrients to achieve
postnatal rates of growth and nutrient accretion approximating those of a normal
fetus during the same period of development (1,2).
Over the past 50 years more research has been conducted in preterm infant nutrition
than in virtually any other field of neonatal care, yet uncertainty persists in clinical
Several parenteral amino acid mixtures for pediatric patients have been introduced
during the last decade and given to infants of low birthweight (LBW) or very low
birthweight (VLBW) to support growth and nitrogen retention.
I would like to thank all the speakers for having participated and giving their experience
on field of expertise.