Breastfeeding does not prevent asthma and allergies

Claims have been made that some degree of resistance to allergies and asthma can be gained by infants who are breastfed. The idea is that proteins are present or are produced in mother’s milk which can help prevent the development of certain allergies.

But researchers at Uppsala University in Sweden think this is fallacious. They assert that genes, environment and lifestyle factors are what impact the development of asthma and allergies. However, they point out that breastfeeding has other positive effects.

“We hope our study can help give new parents a truer picture of the advantages of breastfeeding,” says Weronica Ek, a researcher at the Uppsala University’s Department of Immunology, Genetics and Pathology in a press release.

In the new study, published in the Journal of Allergy and Clinical Immunology, the researchers analysed self-reported data from over 330,000 British adults. This is the largest study of its kind conducted to date.

The results show that those who had been breastfed actually ran a higher risk of developing hay fever and eczema. Those who had been bottle-fed, rather than nursed by their mothers, did not appear to run any higher risk of developing asthma. The researchers point out that this is a population study and unknown factors could be in play.

For instance, mothers who were ill could have been advised to breastfeed their infants, or not to, which would be a factor impacting the study.

Cleaner homes?

The study results show that higher socio-economic status is associated with a lower risk of asthma, but a higher risk of hay fever.

This could have a connection with the “hygiene hypothesis”. This hypothesises that children growing up in cleaner homes come in contact with fewer of certain types of microorganisms. Early exposure to them can have a preventive effect regarding development of allergies.

No documented preventive effect

Solveig Thorp Holmsen is a physician and medical advisor at Norway’s National Advisory Unit on Breastfeeding. She is not surprised by the research conclusions.

“Contrary to what many believe, and have thought for a long time, there has been no documented effect of breastfeeding with regard to asthma and allergies,” she says to ScienceNordic’s Norwegian partner forskning.no

That said, she hastens to add that breastfeeding does have many well-documented health effects and it is recommended also for those who run a higher risk of asthma and allergies.

Breastfeeding still beneficial

Although breastfeeding does not seem to reduce an infant’s chances of developing asthma and allergies, it still has many beneficial health effects. The medical journal Lancet has collected results of studies showing just that. Also, information and knowledge of such effects is mounting and certain effects of breastfeeding can change and additional ones can be added.

One thing is certain: Children who are breastfed are less likely to risk gastrointestinal infections, inner ear infections, respiratory infections and a faulty jaw development. Scientists also speculate as to whether breastfeeding can reduce the risk of child obesity, but the jury is still out there.

Breast milk has also been described as promoting development of the neural system (cognitive development).

Babies are not the only ones benefitting from breastfeeding. Mothers who have breastfed their children lower their risk of breast cancer on average by 4.3 percent for each year they nurse their child. Researchers have found the clearest reduction of risk among younger women.

Medical researchers have also seen that women who breastfeed also lower their risk of developing ovarian and uterine cancers, cardiovascular diseases and diabetes type 2.

References:

Weronica E. E., Torgny K., Carlos A. H., Mathias R-A., Åsa J.:  Breastfeeding and risk of asthma, hay fever and eczema. Journal of Allergy and Clinical Immunology. DOI: 10.1016/j.jaci.2017.10.022. November 2017.

Tracy J. Pitt et al.: Reduced risk of peanut sensitization following exposure through breast-feeding and early peanut introduction. Journal of Allergy and Clinical Immunology. DOI: 10.1016/j.jaci.2017.06.024. August 2017.

Cesar G. Victoria et al.: Breastfeeding in the 21st century: epidemiology, mechanisms, and lifelong effect. The Lancet Breastfeeding Series Group. DOI: 10.1016/S0140-6736(15)01024-7. January 2016.

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Read the Norwegian version of this article at forskning.no

Translated by: Glenn Ostling