In a nutrition book I'm reading they mentioned the higher IQ scores found among breastfed babies but said perhaps it's related to the increased bonding from frequent feedings - since breastmilk is digested faster, bottle fed babies often go longer between feedings and are thus spending less feeding interaction time with parents (the book proposed.) Curious, I started googling. One handed. While nursing. 😉
One study summary said this:
A study published in the American Journal of Clinical Nutrition shows that breastfed infants tested 5.2 IQ points higher than formula fed infants, for a comprehensive study involving 11 different studies and over 7000 children.
The study, to be published in the October edition of the American Journal of Clinical Nutrition was performed by University of Kentucky nutritionist James Anderson.
"Our study confirms that breast-feeding is accompanied by about a five-points higher IQ than in bottle-fed infants," Anderson said.
Within that increase, Anderson and associates were able to separate the benefits from mother-infant bonding from the purely nutritional benefits of human milk.
"Our best estimates are that maternal bonding and the decision to breast-feed account for about 40 percent of that increase, but that 60 percent -- 3.2 points -- are related to the actual nutritional value of the breast milk," he said.
And that is found here with links to the study abstract.
This study said the difference was 11 IQ points.
This study said it's not the breastmilk, it's that women with a higher IQ were more likely to breastfed and thus had babies with higher IQs:
The mother's IQ was a better predictor of whether she would breastfeed than race, education, age, poverty status, smoking, the home environment, or the child's birth weight or birth order. One standard deviation increase in maternal IQ (15 points) more than doubled the odds that a woman would breastfeed her child.
However, if you are part of the 10% of the population with a different gene, then this study says nursing won't improve your child's IQ. But for the other 90% of the population, it says they found a 7 point IQ difference on average.
And this study says that even after adjusting for variables such as social/economic background or maternal education, breastfed babies still averaged higher IQs.
(I would like to add that I typed this entire thing while nursing. Which means I wasn't really interacting with him but we had flirted for awhile and then he passed out and kept chugging away so I let him sleep-nurse until I was done typing. I'm very proud of my crazy nursing-while-doing-other-things talent.)