Breast-fed babies, so the prevailing wisdom
goes, are less likely to have weight problems later in
life. Introducing solid foods later -- at about four or
six months -- is also thought to reduce the risk of being
overweight later in childhood.
But the results of a new study question that wisdom, suggesting
that bottle-fed infants aren't at higher risk for weight
gain compared to their breast-fed peers.
"We found there were no differences in body fat
[overall] at age 5 between breast-fed and formula-fed
infants," said lead researcher Dr. Hillary Burdette,
a nutrition specialist at The Children's Hospital of Philadelphia.
Her team also found no association between introducing
solid foods earlier than recommended and excessive pediatric
weight gain.
The findings are published in the March issue of the
American Journal of Clinical Nutrition.
According to the American Academy of Pediatrics, exclusive
breast-feeding is recommended for a child's first six
months of life and then breast-feeding, supplemented by
foods, is recommended up until 1 year of age. Solid foods
are best introduced at 4 to 6 months of age.
"There have been lots of studies on [infant] feeding
and obesity," but those studies "have had conflicting
results," said Burdette, who is also an assistant
professor of pediatrics at the University of Pennsylvania
School of Medicine.
In their study, Burdette and her colleagues measured
body fat levels for 313 5-year-olds while collecting data
on each child's history of breast-feeding or formula.
They also gathered data on the timing of the introduction
of solid foods into the child's diet.
The team used a technique called dual-energy X-ray absorpiometry
(DXA) to measure body fatness. Burdette noted that previous
studies have focused on body mass index (BMI), a conventional
measure of height related to weight, to determine fatness.
"What makes our study different is [that] we measured
fatness directly, rather than using body weight or BMI,"
she said.
In the study, one-quarter of the mothers never breast-fed.
Of the 231 who did, 88 did so for less than six months,
77 for six months to a year, and 66 for more than a year.
Fifty-two of those women breast-fed for more than a year
without using formula. Half of the mothers followed the
recommendation for introducing solid foods at four months,
and only 8 percent did not start feeding solids until
age 6 months.
The researchers found no differences in fat levels between
bottle-fed or breast-fed children, or in children who
first ate solid foods earlier or later.
Burdette doesn't think her study will end the debate
over links between infant feeding and overweight. And,
she added, "the study doesn't suggest that the current
recommendations need to be changed."
What her study might do, Burdette said, is ease the guilt
of some mothers who aren't able to breast-feed or to breast-feed
as long as is recommended. "Many mothers aren't able
to breast-feed, for numerous reasons, either because they
can't medically, or because of work," she said.
The study results are definitely "not a strike against
breast-feeding," said Dr. Karen Hopkins, a clinical
associate professor of pediatrics at the New York University
Medical Center. The benefits of breast-feeding are well-documented,
she said. "There's no added sugar or fat, no trans-fat"
in breast milk, she pointed out. Studies have found breast
milk protects infants from respiratory tract and ear infections,
as well as improving their cognitive development, among
numerous other benefits.
But, she questions whether the lack of an association
between early solid food feeding and later overweight
will bear out over time. Additional research is needed,
she said, because "at least anecdotally it seems
to be associated."
Hopkins advises parents to try to postpone giving infants
solid foods for six months. "The reasoning is, you
don't want to interfere with breast-feeding. And they
don't need it [solid foods] physiologically," she
said. "There is [also] a possibility they will gain
too much weight too quickly. Early introduction of solid
foods is also associated with the development of food
allergies."
Breast-feeding is ideal, Hopkins said. But whether breast-feeding
for the recommended time period is feasible "depends
on what the patient's situation is," the NYU expert
said.
"Say they are going back to work when the baby
is 2 months. It is possible to pump [milk] but it is hard
to do that, most workplaces are not set up for that. It
takes about 20 minutes twice a day to pump milk, and you
need a private place and someplace to store it,"
Hopkins said.
