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Does breastfeeding prevent respiratory symptoms in infants predisposed to asthma? Release focused on relative risk reduction not definitive

Asthma gene's effect on respiratory symptoms in infancy depends on breastfeeding status

Our Review Summary

breastfeedingThe release describes research into a possible link between breastfeeding and infants having a genetic predisposition to asthma. Researchers drew data from medical records on respiratory symptoms and breastfeeding status and compared them with genotype data gathered from study participants. It claims a 27 percent relative risk reduction among predisposed infants who were breastfed compared to those who weren’t, but we have no other data points, no absolute risk reduction information. The release doesn’t provide enough information for readers to be assured that other factors did not play a role in the results. Reviewers (and presumably other interested readers) were unable to access the actual research paper, or an abstract online, at the time of the review.

[Editor’s note. Several days after reaching out to the issuing organization, an abstract on the study was provided, but it did not change the outcome of the review.]


Why This Matters

The relationship between genetic variance and environmental factors in the eventual development of asthma is not crystal clear. Asthma appears to have a strong genetic predisposition. A child with a parent with asthma is three-to-six times more likely to develop asthma than other children, according to the Centers for Disease Control and Prevention (CDC).

If breastfeeding infants predisposed to asthma could actually reduce their risk of respiratory symptoms by a quarter or more, then that would be a substantial improvement, both to individual and to public health, especially given the growing proportion of children developing asthma and other respiratory problems.


Does the news release adequately discuss the costs of the intervention?

Not Satisfactory

There are two aspects to this release: a genetic mutation which predisposes to asthma and the potential value of breastfeeding in reducing that risk. The release makes no mention of costs in explaining this research. While on the surface breastfeeding carries no economic burden, genetic testing does. The release does not provide any information (as we will note later) about the availability of genetic testing or whether insurance coverage is available.

It’s difficult to quantify, but breastfeeding can have financial costs. There is growing awareness that breastfeeding does exact a toll in time and related earning potential, as explained in this New York Times article.

Does the news release adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The release states that “during the weeks that infants were breastfed, those carrying the asthma risk genotypes, had a 27 percent decreased relative risk of developing respiratory symptoms.” To which we respond: 27 percent of what? We still have no understanding of what the change in absolute risk actually is, a data point that readers deserve and can better use. The release also says that “When infants were not breastfed, those carriers exhibited a trend towards an increased risk of respiratory symptoms,” but provides no data to define that “increased risk” or their perceived “trend.”

Does the news release adequately explain/quantify the harms of the intervention?

Not Satisfactory

Harms associated with breastfeeding are admittedly few and far between. Infrequently, a mother may transfer environmental contaminants to a breastfeeding infant. However, the risks associated with genetic testing in general and the association between the chromosomal variant on chromosome 17, called 17q21, and the risk of the development of asthma are not covered. How reliable is the test?  Is over- or under-diagnosis a risk factor? How likely is it that the child may eventually develop asthma? How many children with the variant develop asthma?

Does the news release seem to grasp the quality of the evidence?

Not Satisfactory

The first statement in this release says that, “Infants who have a genetic profile linked with asthma risk could be protected against respiratory symptoms if they are breastfeed.” But that demonstrative statement exceeds what the design of this study could show — that infants predisposed to asthma can be protected by breastfeeding. Such proof would require a study designed differently than this one.  At best, this study may show a correlation between breastfeeding and reduced asthma risk.  It cannot show that breastfeeding reduces that risk.

Does the news release commit disease-mongering?


There is no disease mongering here. However, we would have liked to have seen some information in the release about the prevalence of asthma in the developed and developing world.

Does the news release identify funding sources & disclose conflicts of interest?

Not Satisfactory

The release provides no information as to the funders of this research, nor does it provide any information on possible conflicts of interest involving the researchers, only one of which is mentioned in the release.  Additionally, neither the abstract nor the full research paper was available when the news release was published, so other information describing the research was unavailable.

Does the news release compare the new approach with existing alternatives?

Not Satisfactory

There was no information provided pertaining to possible alternatives to breastfeeding that also might lead to a reduced risk of asthma among infants, even though there is a wealth of information linking numerous environmental factors to the exacerbation of asthma. A recent review article names more than 100 genetic variants have been associated with the development of asthma along with a host of environmental factors.

Does the news release establish the availability of the treatment/test/product/procedure?

Not Satisfactory

Breastfeeding is indeed routinely available but the availability of genetic testing for the chromosome 17q21 variant is not described. Is this test generally available and if so, is it covered by insurance? The release doesn’t say.

Does the news release establish the true novelty of the approach?

Not Satisfactory

The release claims that “Our study is the first to show that breastfeeding can modify the effect of asthma-related genetic profiles on respiratory symptoms in the first year of life.” Research into the role of genetics in the development of asthma has been ongoing for years, so there is really nothing novel about this research in that regard. If this research could actually show a protective connection between breastfeeding and infants’ reduced risk of asthma, then that surely would qualify as novel enough to warrant a news release.  Unfortunately, this research cannot show that definitively.

Does the news release include unjustifiable, sensational language, including in the quotes of researchers?


The release doesn’t employ sensationalistic language, however, as noted above, some statements may not have been justified based on the other information provided. “Infants who have a genetic profile linked with asthma risk could be protected against respiratory symptoms if they are breastfeed [sic]” and “Our study is the first to show that breastfeeding can modify the effect of asthma-related genetic profiles on respiratory symptoms in the first year of life.” What the study did show was a 27 percent relative risk reduction in children who were breastfed as compared to a group who were not.

Total Score: 2 of 10 Satisfactory


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