Kentucky Study Shows Breast-Feeding Increases Babies' IQ

James W. Anderson, M.D., professor of medicine and clinical nutrition in the UK College of Medicine, found that breast-feeding, compared to formula feeding, is associated with significantly higher levels of cognitive development. The difference increases the longer a baby is breast-fed, and low birth weight babies receive the greatest benefits.

"This study confirms that nutrients in breast milk and maternal bonding have beneficial effects on IQ," Anderson said. "Infants deprived of breast milk are likely to have lower IQ, lower educational achievement, and poorer social adjustment than breast-fed infants."

Anderson theorizes that breast milk provides nutrients required for rapid development of the immature brain. Breast milk may support neurological development by provision of long-chain polyunsaturated fatty acids such as docosahexaenoic acid (DHA) and arachidonic acid (AA).

The study was a meta-analysis, which is the critical review and summary of results from many clinical studies and selected characteristics on the same subject.

This is the first study to quantitatively analyze research that has been done on the topic. This type of analysis is important to separate the effects of maternal bonding from the nutrients delivered with breast milk.

Breast-feeding provides two benefits compared to formula feeding - better nutrition and maternal bonding. The nutritional benefits of breast-feeding are associated with at least a 3.2-point difference in cognitive development compared to formula feeding after adjustment for key factors. This increase is in addition to the 2.1 IQ points that appear related to maternal bonding. The enhanced cognitive development was seen as early as 6 months and was sustained through 15 years of age. The longer a baby was breast-fed, the greater the increase in cognitive developmental benefit.

The study included 20 published reports that met the criteria for the meta-analysis. The analysis accounted for such factors as the mother's age and intelligence, birth order, race, birth weight, gestational age, and socioeconomic status.

The brain is 60 percent lipid in content, and DHA and AA are major lipid components of the brain. During pregnancy the mother mobilizes DHA and AA to support brain development. The mother continues to provide this important "brain food" through her milk. Premature infants are extremely vulnerable because they don't benefit from the intrauterine supply of DHA and AA and have no fat stores of these basic long-chain fatty acids.

Infant formulas sold in more than 60 countries, including most of Europe, contain DHA and AA, but they are not found in formulas sold in the United States.

Recent controlled clinical trials document the beneficial effects of DHA provided in infant formulas. In more than 30 clinical trials, DHA and AA supplementation has proven safe. Formula containing DHA is associated with more rapid development of vision acuity than control formulas without DHA. With DHA supplementation, compared to formula without DHA, IQ differences of up to six IQ points have been noted in various studies.

The study was funded in part by Martek Biosciences Corporation, which produces a plant source of DHA and AA for inclusion in formula sold worldwide. Martek's oil manufacturing plant is located in Winchester, Ky.