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Aug. 16, 2000 -- Chalk another one up for the theory that "whenever possible, breast is best." Premature babies who were fed breast milk had evidence of faster development of an essential part of the brain known as the brain stem than did preemies who received a commercial formula designed for their special nutritional needs.
The research, described in the August issue of the journal Pediatrics, suggests that certain components of human milk can influence the maturing of the brain stem, the part of the brain that controls basic functions such as breathing, swallowing, and eye movement.
Previous studies have also shown that breast-feeding, in addition to boosting an infant's still-developing immune system, is associated with small but long-lasting increases in a child's intellectual abilities and educational achievements. The research has shown that, in general, kids who have been breast-fed as infants for at least one year do better on standardized tests, get higher grades in high school, and earn higher marks in general from their teachers than kids who have been bottle-fed as babies.
"There have been lots of studies of children who are now school age who have eight IQ points better if they were breast-fed as infants, but sometimes it's very hard to separate out some of the environmental factors," researcher Ronnie Guillet, MD, PhD, tells WebMD. "Here, these are preemies who are in the nursery, essentially treated all the same except for receiving breast milk or not, so I think it's a very real development change." Guillet is associate professor of pediatrics at the University of Rochester and a neonatologist at Children's Hospital at Strong in Rochester, N.Y.
In the current study, Guillet and colleagues evaluated the influence of diet on brain stem function and development in 37 babies who were born about eight to 12 weeks premature. In the group, 17 infants received breast milk and 20 received formula for premature babies. At the start of the study, the infants underwent a painless test that measures how well their developing brains respond to a series of sounds. The faster the brain responded to a sound, the more developed the brain stem was.
When the researchers looked at brain waves, they found no differences between the two groups -- breast milk or formula -- at the beginning of the study. But with repeated testing over two to three weeks, they found that the kids who received breast milk had faster response times to sounds than did kids who received formula, suggesting that the breast milk had helped brain tissues to develop faster.
"Our data are the first to suggest an effect of some component of human milk on brainstem maturation," the authors write. They suggest that specific dietary fatty acids in breast milk that are not found in commercial formulas sold in the U.S. may be the crucial difference that gives breast-fed kids a slight but measurable edge in intellectual performance.
It is still not known whether adding the substances, known as long-chain polyunsaturated fatty acids, to formulas would give bottle-fed kids the same advantage as those breast-fed, the authors say.
Although the evidence is heavily weighted on the side of breast-feeding, Guillet says she's aware that not every mother wants to or is able to breast-feed her child.
"It's a fine line," she tells WebMD, "because on the one hand you don't want to make these moms who are already guilty about delivering prematurely guilty if they choose not to breast-feed. But on the other hand you want to encourage them into the right thing to do [for their infant]."