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The World Health Organization, the
American Academy of Pediatrics, and all major health organizations
recommend that all infants should be exclusively breast-fed for
the first 6 months of life, and breast-feeding should be continued
while adding weaning foods for the next 6 months and then for as
long as mother and child desire (unless there is a medical contraindication).1,2 Human
milk has evolved for the human infant and is ideally structured
to meet the nutritional needs for infant growth and development.
It provides a variety of bioactive components that protect from
infection and promote normal development.3 These
include hormones (oxytocin, thyroid-stimulating hormone, growth
hormone, thyroxine, cortisol insulin), growth factors (epidermal
growth factor, nerve growth factors, somatomedin-C, insulinlike
growth factors), neuropeptides (somatostatin, neurotensin, vasoactive
peptides), inflammatory and immunomodulatory agents (cytokines), and
pheromones, which stimulate suckling behavior.4-6 The
relative composition of milk and its bioactive agents differ from
one mother to the next depending on her past experience, her genetic
makeup, her diet, and the gestational age of her infant. The composition of
the mother’s milk changes over time following birth and
over the course of the feeding.
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The beneficial effects of providing species-specific nutrition
in the early months may extend far past the time of weaning and
have been described as “nutritional programming.” Human milk
significantly influences growth, neurocognitive development,7 and
cardiovascular disease.6-9 Advantages of breast
milk also are observed in the preterm or small-for-gestational-age
infants, especially in the prevention of necrotizing enterocolitis,10 but
supplementation with specific nutrients may be required to assure
optimal growth and neurocognitive development.11
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The concept of nutritional programming implies that a stimulus
or insult during a critical or sensitive period of development can
have long-term or lifetime effects. A beneficial effect of human
milk on long-term development of a healthful childhood and adult
intestinal microbiome has been proposed but is not yet established.12 Colostrum,
with its host of bioactive factors, is the infant’s first
immunization and likely begins the interaction between breast milk
and intestinal mucosal factors that control the development of the
intestinal microbiome. Factors known to interfere with the normal
establishment of a beneficial flora include delayed feedings, antibiotics, cesarian
section delivery, and formula feeding.9,12 Human
milk supports the prevalence of beneficial microflora (bifidobacteria
and lactobacillus) and potentially inhibits the establishment of
pathogenic microbes.6 Exclusive breast-feeding
for at least 4 months is also associated with a reduction in atopic
disease, indicating that later immunologic responses are possibly
programmed during infancy.13
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Breast-feeding appears to establish a more healthful feeding
pattern throughout life that influences growth parameters. The physiologic weight
loss in the first several days and subsequent growth pattern of
the breast-fed infant differs from that of formula-fed infants.14 Some studies
suggest that breast-fed infants may have lower rates of obesity
compared to formula-fed infants.15,16 This finding
has led to the establishment of ...