Most doctors encourage breastfeeding by emphasizing that breast milk contains antibodies to help babies fight off harmful bacteria and other germs. However, a recent study, published in the Journal of Allergy and Clinical Immunology, suggests that breastfeeding might not always protect babies against allergies and asthma.
Surprised? You shouldn’t be. Past studies have often shown inconsistent results, but because this one focused solely on the impact that breastfeeding has on asthma, hay fever and eczema (and is also one of the most extensive studies of its kind), it’s drawing a lot of attention.
Using self-reported data from more than 330,000 middle-aged individuals in the U.K., researchers determined that breastfeeding—while also factoring in genes, environment and lifestyle—could increase the risk of developing hay fever and eczema.
"Our study shows that individuals that were breastfed as babies have an increased risk of developing hay fever and eczema, while breastfeeding doesn't seem to have an effect on asthma," says Weronica Ek, researcher at Uppsala University's Department of Immunology, Genetics and Pathology, who led the study at the Swedish institution.
Findings showed that increased socioeconomic status appeared to lower the risk of asthma while at the same time increasing the risk of developing hay fever. This evidence, according to researchers, supports another theory—the "hygiene hypothesis"—which states that growing up in a cleaner environment increases the risk of being diagnosed with allergies due to a lack of early childhood exposure to microorganisms.
Further analysis determined that high BMI—a measure of body fat based on height and weight—could also elevate the risk of asthma, hay fever and eczema. On the flip side, participants who exhibited a higher birth weight were less susceptible to these conditions.
Though scientists were unable to identify any protective supplements that breastfeeding might offer toward asthma or other allergies, they did note that this was an observational study only, which does not allow for clinical recommendations. In other words, the study does not imply that breastfeeding is harmful to newborns; it merely suggests that it might not protect them against asthma, hay fever and eczema.
In addition to that, underlying factors that researchers were unaware of could have affected their findings. For instance, mothers who have the diseases themselves might have been recommended to breastfeed or not to breastfeed. If unreported during analysis, this information could have easily affected their conclusions.
The researchers stress that breastfeeding has a positive effect on the overall health of a baby and findings such as these should not be used to encourage or discourage new moms from making the choice that works best for them.
Though the authors of the present study do not take any positions as to whether breastfeeding represents the best source of nutrition for newborns, Ek believes that analyzing the impact that breastfeeding has on allergies and asthma might offer new insight and "give a more correct picture of the health benefits of breastfeeding."