Iron Deficiency Anemia and Asthma: Is There a Link?
Recently, a friend asked if I was aware of a link between asthma and iron deficiency. I told her it sounded like something I’d heard before, but that I would look into it. After all, both iron deficiency anemia and asthma can share the symptom of shortness of breath, and both are common, so it is feasible that there be some sort of overlap.
Objective or subjective: Is there a link?
Interestingly, while there are a plethora of results on Google on this subject, as well as people contemplating their personally correlated experiences, the writing seems to be based on the findings of just a handful of research articles (and thus, 3 or 4 core research studies). The most prominent include, "Is Iron Deficiency Anemia a Risk Factor in Asthmatic Children?" (2013), "The impact of anemia and hemoglobin level as a risk factor for asthma and allergic diseases" (2015), "Iron deficiency anemia as a risk factor in childhood asthma" (2016), and "Iron Status is Associated with Asthma and Lung Function in US Women" (2016).
The first three articles above focus on children and the last focuses on women. This is, presumably, due to the fact that men are less predisposed to iron deficiency anemia. This may be the reason they are excluded from the most easily accessed selection of the research.
What does the research say?
The research indicates anemia was more common in asthmatic children than non-asthmatic children1, that there is a positive correlation between higher hemoglobin and better lung function results in children2, and that, in women, higher stored iron in the body decreased current asthma symptoms, and lower circulating iron and “higher tissue iron need” (need for replenished iron by the tissues like muscle) was correlated with lower lung function.3
The final pediatric study (Fida & Kamfar, 2013) states, “From the data of this study it can be concluded that incidence of iron deficiency anemia is not uncommon in pediatric patients with bronchial asthma.” and “Further studies are needed to assess the relationship between severity of asthma and the degree of anemia...”4
So are asthma and anemia connected?
While there may be a correlation between asthma symptoms and iron deficiency, as indicated by the study of adult women that followed fluctuations of iron levels in response to symptoms (or vice versa), the data involved in the studies of children conjures more curiosities for me.
Socioeconomic status is not an item of consideration in the studies I reviewed, although there is a wealth of research done on low-income populations, specifically children, with asthma. However, low income may precipitate both asthma and/or poor asthma control, as well as malnutrition, including iron deficiency.5,6 This could be a compounding factor on the evidence as presented, although iron deficiency is not a burdensome problem presently faced by children in the United States.7
Given a lack of demonstrable causative effect of asthma to induce iron deficiency or vice-versa, I remain curious about the origins of the correlation between asthma/asthma symptoms and iron deficiency. For instance, can anemia induced dyspnea be mistaken for asthma or does it truly exacerbate asthma symptoms? From what research has been done, there is significant evidence of the correlation between asthma/asthma symptoms and iron deficiency. We just need to better understand the implications of this correlation.
Does cold weather impact your asthma?