Breast feeding "Those who were breast-fed scored on average three points above the population mean of 100 on the IQ test, whereas those who were not breast-fed scored about three points below the population mean," Moffitt says. In other words, breast-feeding led to a gain of a few IQ points, whereas those using baby formula in lieu of mom's milk led to a slight dip.
As for the study's implications on the nature / nurture debate, Linda Gottfredson, a professor of education at the University of Delaware, says that a person's DNA is not really a blueprint, as it is commonly portrayed. "[Genes] are more like playbooks," she says. "It's not nature or nurture, but your genes operate frequently by making you more susceptible or less susceptible to certain environmental conditions." Hence, the withdrawal of breast milk from the diets of babies with a certain genetic predisposition resulted in a negative effect on intelligence.
The exact mechanism by which the enzyme coded by FADS2 might influence IQ is not known, but Moffitt suggests two possible roles: The gene variants may affect the conversion of dietary precursors to long-chain polyunsaturated fatty acids, which aggregate in the brain in the early months after birth. Alternatively, the presence of long-chain polyunsaturated fatty acids may act on the gene itself, causing it to turn on or off, thereby affecting the metabolic pathway the acids use.
The authors note that since the time that study subjects were breast-fed, many baby formula manufacturers have begun adding fatty acid supplements to their products, potentially giving them an IQ boosting effect.
Yes, this touches on a lot of important issues. Is it sufficient to supplement the appropriate lipids, if breast milk is not available? If 90% of children have the good variant of the gene, could the other 10% be helped by supplemental lipids, or anything else? Is the gene heritable?
It looks like a child's IQ might actually decrease from breastfeeding if you don't have the gene.
IQ geneNinety percent of the children in the two study groups had at least one copy of the "C" version of FADS2, which yielded higher IQ if they were breast-fed. The other 10 percent, with only the "G" versions of the gene, showed no IQ advantage or disadvantage from breastfeeding.
The gene was singled out for the researchers' attention because it produces an enzyme that helps convert dietary fatty acids into the polyunsaturated fatty acids DHA (docosahexaenoic acid) and AA (arachidonic acid) that have been shown to accumulate in the human brain during the first months after birth.
It seems like genetic screening could give information on optimizing the amount of DHA/AA a baby should get. It looks like if you breast feed and don't have the gene, you could actually lower your childs IQ. Of course this study was done before milk was supplemented with DHA, so I don't know how much it applies. If all the gene does is convert dietary fatty acids to DHA, then I guess just supplementing with DHA would work.
