Breast is Best? Harvard Study Says Breastfed Babies Have Higher IQ's

Young children who were breastfed as infants are smarter and performed higher on intelligence tests than their formula-fed counterparts, and the longer and more exclusively they were breastfed, the greater the difference, Harvard University researchers said.

The study followed 1,312 expectant mothers who enrolled between 1999 and 2002 in Project Viva which examined their pregnancy, labor and the overall health of the child.

The findings, which were published Monday in JAMA Pediatrics, found that each additional month a child was breastfed resulted in better language skills at 3 years old and intelligence at age 7, compared with babies who had formula milk. The study is one of the largest to analyze the impact of breastfeeding on a child's intelligence.

 "With this we can close the book and decide there is a link between child breastfeeding and intelligence," said Christakis, a professor of pediatrics at Seattle Children's Research Institute, a pediatric medical research center, in a July 26 telephone interview. "The fact that breastfeeding really promotes cognition in our children is something we should all care about. It takes a village to breastfeed a child. We should take the actions necessary not to just initiate breastfeeding but to sustain it."

Still, breastfeeding is not the only contributing factor to intelligence, said Mandy Belfort, the lead study author and a neonatologist at Boston Children's Hospital and an assistant professor of pediatrics at Harvard Medical School.

"It adds to the literature in support of the idea that breast-feeding does positively impact a child's intelligence. I don't think there's any one study that's going to be a complete slam dunk, but it's definitely evidence in support of that idea," Belfort said.

The study also debunked the previously held associated that a mothers' consumption of fish while lactating increased the child's cognitive development. 

"We found a little hint in that direction, but nothing definitive," says Belfort, who is also an assistant professor of pediatrics at Harvard Medical School. "And we certainly didn't find any evidence that eating fish while breast-feeding was harmful, which is important because there are some concerns about mercury in fish being toxic to the developing brain."

The study also highlights the need to support mothers in the workplace and in public to enable them to breastfeed their babies during the first year of life, said Dimitri Christakis, who wrote an accompanying editorial in the journal.