Not all research is created equal
Breastfeeding prevents allergies. No it doesn’t. Breastfeeding helps prevent obesity. No it doesn’t. Breastfeeding babies have higher IQs later. No they don’t. It is dizzying to follow the research reports on the benefits of breastfeeding. Just when there are several studies showing a certain benefit, there comes along one that demonstrates otherwise. What in the world is going on?
I think that “Summarizing the health effects of breastfeeding” gives a good clue to what is going on. http://onlinelibrary.wiley.com/doi/10.1111/apa.13136/epdf. The act of breastfeeding is so complex in terms of how long, how much, supplements given, pumped breastmilk, timing of feedings, mother’s supply, feeding method, and so on. The milk is so complex in terms of daily variations, monthly variations, variations over the course of breastfeeding, genetic variations, and so on. The family in which the breastfed baby grows up is so complex in terms of maternal nurturance, life style, socio-economic influences, parental education and so on. The variables in any research study are enormous and although researchers attempt to mitigate those variations in the design of the study, it is virtually impossible to take them all into consideration. So we get research that is contradictory. If the new research not outright contradictory, at a minimum, it may draw differing conclusions.
So, just when you feel comfortable making a claim about a facet of the superiority of breastmilk, know that some research will come out that says something different. Studies that are replicated and come out with similar results are the most reliable. Be critical when you read research. Are there variables that were not considered in the study design? Who funded the study? Do the results support the conclusion?
Don’t be shaken by the fluctuations in published literature. Breastfeeding is more art than science.