Does Breastfeeding Boost IQ?
Study Shows Breastfed Kids Score Better on Some IQ Tests
WebMD News Archive
Breastfeeding and IQ: Test Results
When the kids reached age 6 1/2, the children's pediatricians gave them
intelligence tests. If they were in school, teachers evaluated their academic
performance in reading, writing, math, and other subjects.
The strongest effect, Kramer says, was improvement in verbal IQ. On average,
those in the intervention group scored 7.5 points higher on tests measuring
verbal intelligence, such as vocabulary, which was statistically significant
(meaning not due to chance). They scored 2.9 points higher on those tests
measuring nonverbal intelligence and 5.9 points higher on tests measuring
Kramer says the nonverbal and overall IQ test score differences were not
statistically significant -- but just barely. He says the more important point
is that he found an overall trend to improvement in the measures in the
long-term or exclusively breastfed children.
Teachers rated the breastfed intervention group's reading and math better
than the control group children.
"I think it's a modest effect," Kramer says. The IQ advantage for
the long-term breastfed children, he says, is similar to what has been found in
research for first borns vs. younger siblings.
"It's not the difference between a genius and a mentally retarded
child," he says.
Breastfeeding and IQ: Breast Milk or Social Interaction?
Whether the boost in IQ is due to the breast milk itself -- such as healthy
fatty acids or other substances -- or the physical and social interaction that
is part and parcel of breastfeeding is unknown, Kramer and others say.
"A mother who breastfeeds is likely to spend more time with her
child," he says, as well as read to them later and do other activities.
"The amount of time, the closeness, the way she interacts with the kids,
undoubtedly differs between breastfeeding and non-breastfeeding
The bulk of studies on the topic, he adds, have shown a positive link. One
notable exception: a study published in 2006 in the British Medical
Journal concluded that breastfeeding has "little or no effect on
intelligence in children." The study involved more than 5,400 children.
Kramer says his study is sounder because of a more rigorous methodology.