October 17, 2023
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Key takeaways:
- Only 25% of infants had been introduced to cashew by age 12 months.
- Infants with one or both parents born in Asia were more likely to be sensitized.
Cashew allergy impacted 1.49% of infants and cashew sensitization impacted 1.96% of infants, both at age 12 months, according to a study published in The Journal of Allergy and Clinical Immunology: In Practice.
Eczema was associated with increases in cashew allergy, and peanut allergy was associated with cashew allergy as well, Tim Brettig, MBBS, senior study doctor of Population Allergy Group at Murdoch Children’s Research Institute and pediatric allergist and immunologist at Royal Children’s Hospital, and colleagues wrote.
There was no association between the timing of introduction to cashews after age 12 months and cashew allergy. Image: Adobe Stock
The study involved 1,414 infants from the EarlyNuts cohort who had skin prick testing for cashew at age 12 months. Using a cutoff of 3 mm or greater, the SPT revealed allergy for 1.49% (95% CI, 0.91%-2.44%) and sensitization for 1.96% (95% CI, 1.28%-2.99%)
With a cutoff of 2 mm or greater, 3.71% (95% CI, 2.72%-5.07%) of the infants were sensitized to cashew. There were no SPT results larger than 8 mm.
Tim Brettig
Also, 36 infants (1.9%) had oral food challenges for cashew, with 14 (38.9%; 95% CI, 23.1%-56.5%) demonstrating allergic reactions. The researchers did not perform OFCs on 49 infants who had SPT results of 1 mm or larger.
These infants who did not have OFCs included 33 with a convincing clinical history of tolerance, five with a convincing clinical history of allergy, five who were probably tolerant, and six who were unknown, according to the researchers.
Also, 25% (n = 302; 95% CI, 22.7%-27.8%) of the infants had been introduced to cashew before age 12 months. The researchers found no evidence of an association between the presence of eczema (OR = 1.21; 95% CI, 0.85-1.71) or a peanut allergy (OR = 1.44; 95% CI, 0.57-3.65) and the timing of cashew introduction.
Researchers additionally found that 16.7% (95% CI, 6.9%-31.3%) of infants with a peanut allergy also had cashew allergy, compared with only 0.8% (95% CI, 0.4%-1.4%) of those who did not have a peanut allergy.
Adjustments for confounding variables produced strong associations between peanut allergy and both cashew allergy (adjusted OR = 19.3; 95% CI, 5.44-68.43) and cashew sensitization (aOR = 8.88; 95% CI, 2.98-26.47).
Further, cashew allergy appeared more prevalent among infants with vs. without doctor-diagnosed eczema in their first year (3.4%; 95% CI, 1.7%-6% vs. 0.6%; 95% CI, 0.2%-1.3%), with adjusted models showing associations between eczema and cashew allergy (aOR = 5.75; 95% CI, 2.08-15.88) and cashew sensitization (aOR = 4.46; 95% CI, 1.91-10.45).
The researchers did not find any associations between introduction of cashew after age 12 months and sensitization or allergy.
However, the researchers continued, infants with one or both parents born in Asia were more likely to be introduced to cashew after age 12 months (OR = 1.36; 95% CI, 1.02-1.8), and there was evidence of an association between parents born in any Asian country and cashew sensitization (aOR = 4.35; 95% CI, 1.75-10.78) but not with allergy.
Finally, the researchers found little evidence for associations between sensitization or allergy and siblings or parents with food allergy, family or parental histories of atopy, the infant’s country of birth or the infant’s sex.
Although there were no associations between the age of cashew introduction and the presence of cashew allergy, the researchers were unable to conclude with confidence that this association did not exist based on this observational study and that further studies with large populations may better define this association and determine the benefits of early introduction among infants who are at risk for allergy.
Sources/Disclosures
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Disclosures:
Brettig reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Megan Hilbert, MS, RDN
It is significant that this is the first study to not only examine the prevalence of cashew allergy but also its risk factors because cashews are the leading tree nut allergy. This is incredibly important, as this study’s findings and future studies on this topic can help inform us of when to introduce vs. when not to introduce tree nuts such as cashews into the diets of infants based on these risk factors.
Other research shows us that only 5% of infants eat cashews by age 12 months and that 3.6% of those children who do not get introduced to cashews by age 12 months end up developing cashew allergies by age 6 years. This helps show us that children who are introduced to cashews before age 12 months are less likely to develop a cashew allergy.
It has been my experience that cashew allergy is quite rare, but those children who do get introduced to tree nuts and peanuts at an early age tend to be less likely to develop allergies and sensitivities to these foods and food groups. In age cohorts where tree nut and peanut allergy guidelines were different (ie, holding off on introducing these foods until after age 1 to 3 years), there is a much higher prevalence of these allergies.
When we are born, our immune system begins to do its job by taking stock of things in our environment and learning what is friend vs. what is foe. We are not exactly sure why early introduction is important, but it is clear that introducing these foods in small quantities helps to train or teach the immune system that foods, such as cashews, are not a threat. The longer we wait to train our immune system, the more it seems to identify foods introduced later as threats.
These findings can help doctors assess for risk factors that may point to cashew allergy, and they can also help inform doctors about best practices for introduction not only to cashews but other tree nuts. Cashew allergies are rarer than peanut allergies, but 1.49% of the infant population having this allergy is not insignificant and it is important for clinicians to be informed.
This study may also help doctors identify which infants may need to do in-office testing with medical supervision when cashews are introduced if they have eczema or a peanut allergy.
It would be great to have further research on other tree nuts, especially almonds due to their prevalence in the food system. I would also like to see further research done on the timing of introduction, as this study was not able to find an association between the timing of introduction of cashews after age 12 months and the prevalence of cashew allergy.
Reference:
Peters RL, et al. J Allergy Clin Immunol. 2020;doi:10.1016/j.jaci.2020.07.003.
Disclosures: Hilbert reports employment as a registered dietitian nutritionist with Top Nutrition Coaching.
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