Does breastfeeding cause or correlate with benefits?

There’s an interesting piece on BBC News that has a different take on the two breastfeeding stories we ran recently that suggested that breastfeeding during the early years might aid brain development and reduce risk for mental illness.

A study published this week in the British Medical Journal suggests that the advantage of breastfeeding on baby’s intelligence could be explained not by the effect of breastmilk on the infant’s developing brain, but by the fact that women who breastfeed are more likely to have higher IQs.

This is perhaps because IQ is correlated with social and economic class, and people in these classes are generally more likely to follow health advice promoted in education campaigns.

Hence, these babies might just be more likely to inherit neurodevelopmental advantages from their mothers (IQ is known to be partially heritable), and are probably more likely to benefit from a range of other factors which better socioeconomic conditions bring.

I suspect that advantage seen in breastfed babies might be a combination of social and genetic factors, as well as the effects of breastmilk.

We know that good nutrition in the early years is crucial to good brain development and breastmilk is a tailor-made for the purpose.

However, the brain also develops through interaction with the environment, so this nutritional advantage has to be balanced against social and educational experience.

Link to BBC News story “Breast milk ‘does not boost IQ'”.
Link to abstract of original study from BMJ.