Children with peanut allergy often sensitized to other legumes
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At least two-thirds of children with a peanut allergy also were sensitized to one other legume, one-quarter of whom were diagnosed with a legume allergy, according to a study published in Pediatric Allergy and Immunology.
This high prevalence indicates a need to investigate legume consumption and sensitization among children with peanut allergy, Timé Muller, MD, of the pediatric allergy department at Children’s Hospital, University Hospital of Nancy in Vanduvre-lès-Nancy, France, and colleagues wrote.
The study involved 195 children (69.7% boys) with peanut allergy admitted to the pediatric allergy department at the hospital between Jan. 1, 2017, and Feb. 29, 2020. These children had a median age at peanut allergy diagnosis of 4 years (range, 2-6). Also, 98.4% of them had at least one other atopic disease.
The cohort included 118 children (62.4%) with another food allergy in addition to legumes, including egg (57.6%), cow’s milk (33%), cashew nut (39%), pistachio (23.7%) and hazelnut (30.5%).
Patients experienced anaphylaxis in 51.5% of their inaugural reactions and 69.2% of their oral food challenges, with no grade 5 reactions recorded.
Among the 191 children in the cohort with data pertaining to sensitization, 63.9% (n = 122) were sensitized to at least one legume, including fenugreek (66.3%), lentil (42.2%), soy (39.9%), pea (38%), lupine (34.2%), chickpea (33.3%), broad bean (30.6%) and bean (21.5%).
Overall, 34 children (17.4% of the population; 27.9% of the sensitized children) were allergic to at least one legume. Six of the children (3.1%) had allergies to more than one legume.
Among sensitized children, eight of 38 were allergic to lentil (21%), 12 of 63 were allergic to lupine (19%), eight of 52 were allergic to pea (15.4%), six of 61 were allergic to fenugreek (9.8%), five of 61 were allergic to soy (8.2%) and two of 27 were allergic to chickpea (7.4%).
Histories of anaphylactic reactions included 100% for soy, 50% for lupine, 62.5% for lentil, 50% for chickpea, 50% for pea and 33.3% for fenugreek. The researchers noted that mild isolated cutaneous reactions were rare, with 50% of reactions being severe, frequently with manifestations of asthma.
Considering the prevalence of sensitization to legumes and incidence of anaphylactic reactions among this population of children with peanut allergy, the researchers wrote, further research into and comprehensive reporting about these risks are necessary.
Perspective
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This study addresses a common question: “My child has peanut allergy. Do I need to worry about other beans?” The face value answer is that there is a 17% risk, and lentil, lupine, pea and soy are prominent allergies. However, there are several cautions I would apply in formulating a take-home message.
First, this is a chart review study of a highly atopic referral population requiring not only a peanut allergy but also an investigation about an associated legume allergy. Also, seeing that 100% of those with soy allergy in this study had severe reactions suggests a special selection.
To me, these points mean it is very likely that the rate of concomitant legume allergy is inflated compared with the average child with a peanut allergy. Other studies suggest that less than 10% of those with peanut allergy have another legume allergy.
Second, the study likely reflects the diet in France. Although there are not a lot of similar studies, the specific beans identified as prominent allergens vary by the local diet — for example, the relative prominence of lupine, lentil and fenugreek in the current study compared with chickpea and lentil being prominent in Spain. Fenugreek, until this report, has been rarely described.
For additional perspective, one can ask if peanut has anything to do with the identification of allergy to other legumes. Perhaps these are just allergy-prone children, and some percentage will have allergies to various foods. Children in this current study had much higher co-allergy to non-legumes such as egg (58%), milk (33%) and cashew (39%). The reader also should note that allergies to all the beans in this report have been described in people without a peanut allergy.
For the clinician, a very important observation from this study is that the overall percentage of children with a positive allergy test (64%) far exceeded the percentage with a true allergy (17%). Be careful not to test unless you have a very good reason!
The authors suggest widespread testing in those with peanut allergy. This conclusion may be appropriate to their specific study population, but it could be misleading and unnecessary if applied to everyone with peanut allergy. I would emphasize that, overall, having a peanut allergy is not likely to be associated with allergy to another legume and, in most cases, no additional testing will be needed.
I think the study also confirms my own conclusion to generally not be concerned about beans that do not appear “potent,” such as navy, lima, white, kidney and string beans. There are circumstances where I currently may do additional testing, and I consider history, severity, test results and family diet and preferences.
For example, if I have a patient with multiple food allergies including peanut allergy who has refused to eat “potent” legumes such as pea, soy, chickpea or lentil, or who has had a reaction to any of them, then I may extend testing and evaluation toward beans not eaten. However, doing so will likely identify sensitization (positive tests) that may not indicate true allergy and may require medically supervised feeding to confirm a diagnosis.
More studies in different populations would be needed to determine the necessity, yield and risks for more wide-spread testing.
Reference:
Cox AL, et al. J Allergy Clin Immunol Pract. 2021;doi:10.1016/j.jaip.2020.09.030.
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