One of the most interesting studies I’ve come across while preparing for my comprehensive exam showed that the benefits of breastfeeding can depend on one’s genes. In the study, the authors compared the IQs of children who were breastfed in contrast to children who were formula fed. Normally, we expect that the children who were breastfed will have a higher IQ. In keeping with dogma, this is what the authors found in those with a certain variation of the FADS2 gene. However, in children with a different variant of the FADS2 gene, they found something surprising. In these children there was not difference in the IQ of those who were breastfed versus those who were formula fed.
So what does this mean? Well, perhaps there is a gene that either accentuates the ability of the breast milk to promote neural development, or conversely, there may be a gene that prevents the ability of breast milk to improve neural function. At this point, they’re really not sure.
I want to be crystal clear about something…these findings should not be interpreted as a rational for formula feeding. Breast milk is–and always will be–the gold standard when it comes to infant nutrition. Nevertheless, this study illustrates some of the interesting things going on inside the body, the things we (probably ) can’t control, and perhaps, the things that make us who we are.
I learned about this fact from: Caspi et al. Moderation of breastfeeding effet on the IQ by genetic variation in fatty acid metabolism. PNAS, 104(47): 18860-18865.