Breastfeeding is the feeding of an infant or young child with breast milk directly from female human breasts, via lactation, rather than from a baby bottle or other container.
The longstanding belief that breastfeeding correlates with an increase in the IQ of offspring was challenged in a 2006 paper published in the British Medical Journal. The results indicated that mother's IQ, not breastfeeding, explained the differences in the IQ scores of offspring. The results of this study argued that prior studies had not allowed for the mother's IQ. Since mother's IQ was predictive of whether a child was breastfed, the study concluded that "breast feeding itself has little or no effect on intelligence in children." Instead, it was the mother's IQ that had a significant correlation with the IQ of her offspring, whether the offspring was breastfed or was not breastfed. The study has been subject to various criticisms. Another study found a positive effect of breastfeeding also after controlling for parental IQ. Another study concluded that breastfeeding increases IQ 8.3 points on average.
A study shows that breastmilk can raise IQ by 7 points if the infants had a "C" version of the FADS2 gene. Those with the "G" version have no IQ advantage.
It has also been proposed that the omega3 fatty acids that are found in high doses in breast milk, and that are known to be essential constituents of brain tissues, could at least partially account for an increase in IQ.
Research and Studies
Studies have examined whether breastfeeding in infants is associated with higher intelligence later in life. Many have found a connection:
- Horwood, Darlow and Mogridge (2001) tested the intelligence quotient (IQ) scores of 280 low birthweight children at seven or eight years of age. Those who were breastfed for more than eight months had verbal IQ scores 6 points higher (which was significantly higher) than comparable children breastfed for less time. They concluded "These findings add to a growing body of evidence to suggest that breast milk feeding may have small long term benefits for child cognitive development."
- A 2005 study using data on 2,734 sibling pairs from the National Longitudinal Study of Adolescent Health "provided persuasive evidence of a causal connection between breastfeeding and intelligence." The same data "also suggests that nonexperimental studies of breastfeeding overstate some of breastfeeding's other long-term benefits, even if controls are included for race, ethnicity, income, and education."
- The 2007 review for the WHO "suggests that breastfeeding is associated with increased cognitive development in childhood." The review also states that "The issue remains of whether the association is related to the properties of breastmilk itself, or whether breastfeeding enhances the bonding between mother and child, and thus contributes to intellectual development."
- Two initial cohort studies published in 2007 suggest babies with a specific version of the FADS2 gene demonstrated an IQ averaging 7 points higher if breastfed, compared with babies with a less common version of the gene who showed no improvement when breastfed. FADS2 affects the metabolism of polyunsaturated fatty acids found in human breast milk, such as docosahexaenoic acid and arachidonic acid, which are known to be linked to early brain development. The researchers were quoted as saying "Our findings support the idea that the nutritional content of breast milk accounts for the differences seen in human IQ. But it's not a simple all-or-none connection: it depends to some extent on the genetic makeup of each infant." The researchers wrote "further investigation to replicate and explain this specific gene–environment interaction is warranted."
- In "the largest randomized trial ever conducted in the area of human lactation," between 1996 and 1997 maternity hospitals and polyclinics in Belarus were randomized to receive or not receive breastfeeding promotion modeled on the Baby Friendly Hospital Initiative. Of 13,889 infants born at these hospitals and polyclinics and followed up in 2002-2005, those who had been born in hospitals and polyclinics receiving breastfeeding promotion had IQs that were 2.9-7.5 points higher (which was significantly higher). Since (among other reasons) a randomized trial should control for maternal IQ, the authors concluded in a 2008 paper that the data "provide strong evidence that prolonged and exclusive breastfeeding improves children's cognitive development."
However, some have not found a connection:
- In 2006, Der and colleagues, having performed a prospective cohort study, sibling pairs analysis, and meta-analysis, concluded that "Breast feeding has little or no effect on intelligence in children." The researchers found that "Most of the observed association between breast feeding and cognitive development is the result of confounding by maternal intelligence."
- The 2007 review for the AHRQ found "no relationship between breastfeeding in term infants and cognitive performance."
For more information and reference:
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