One of the things I truly love about family practice is all that I get to learn from my clients. I can't think of a lot more awful than a profession full of routine and monotony, but I know many really thrive this way and I am grateful for you. Personally, I am so full of curiosity I can struggle to stay on task. More recently I was doing my Dr. Quinn thing, traveling to families in my community and beyond who were in need of primary care, and one of my visits was to address a newly discovered nut allergy; the cashew.
I am quite familiar with nut #allergies in general, at least as a clinician, even really severe ones and am often humbled by the challenges these families must endure when their child has reactions significant enough that a whiff of peanut can compromise their every breath. This cashew allergy though revealed a bit of ignorance on my part, so I thought I'd dig into the research a little bit here and share some of that with you because just like peanut allergies seemingly snuck into our reality a decade or two ago, it seems cashew allergies are more recently on the rise too ranking now as the second most common allergy-causing tree nut.
Tree nut allergies affect more than 2% of children, and because cashews are being consumed more often, up as much as 32% in the last decade, cashew nut allergies seem to be a growing problem (Ertugrul et al, 2021). We typically recognize this in our children younger than 5 years of age with rapid onset of symptoms significant enough to cause life-threatening #anaphylaxis.
Cashew allergies in particularly seem to be especially potent and of course, avoiding them is the best treatment plan, but this can be hard to do with #cashews included in so many food products (Ertugrul et al., 2021). Part of this is an effort to avoid both dairy and #gluten, so cashew milk and cashew flour are great alternatives for these so that most children demonstrate some level of sensitivity to cashews in spite of never having consumed cashews. In fact, the majority of children allergic to hen's eggs or cow's milk do seem to develop a tolerance to cashews over time, but when anaphylaxis is the response, this is not one we want to risk through repeat exposures. The cashew nut allergy also tends to show lifelong persistence similar to other nuts.
What Other Foods Might My Child React to if Allergic to Cashews?
Cross-reactive foods are those with similar chemical structures that the immune system may tag as threats because they are in the same family, with the cashew part of the Anacardiacea family (Ertugrul et al., 2021 & Bastiaan-Net et al., 2019). Pistachio sensitivity is present in approximately 34-82% of those who react to cashews, depending on their consumption in any particular territory. It is recommended that if you know you have a cashew allergy, to avoid pistachio as well. Mango and pink peppercorn are other likely potentials because they are in the same anacardiacea family, but far few reports of mango have been identified as a cross-sensitization.
Here's what I didn't realize, the Anacardiacea family also includes the botanical sumac. Personally, I can walk through this stuff, as well as poison ivy, and it just doesn't bother me, or my children, but I know like my former husband, others can get a whiff of it in the air and they are already breaking out in a horrible rash. This particular little lady, who ate the cashew and had an anaphylactic reaction, also had a horrible rash on her bum every time she stooled over the next few days because clearly, even the littlest hint of cashew and its oil was perceived as threatening and toxic to her little body.
The oil found in the nutshell of the cashew is known to cause contact dermatitis and is related to the oils found in the leaves of poison oak and in the skin of mangos. Certainly one should avoid poison #sumac, but if you know of a family history that is especially sensitive to their plants, then consider the potential a cashew allergy may present itself, even mangos.
The rosacease and proteaceae families are other nut families within the same subclass of rosidae that the cashew originates, so it may be plausible that some may show cross reaction to almonds and macadamia nuts as well (Bastiaan-Net et al., 2019). There are no reports of such however. Other sources have suggested hazelnuts, walnuts, sesame, and buckwheat on the potential lists as well, but not a lot of rationale besides their being tree nuts.
As well, for those who react to mangos, this may trail into the "celery-mugwort-spice syndrome" and even the "latex-fruit syndrome," because they too have similar allergens, but even more rare. Peanuts are different from tree nuts in that they are actually a legume. However, 30% of people with a peanut allergy will also be allergic to at least one type of tree nut.
What do We do Now?
When a child presents with suspect symptoms of allergy and we aren't quite sure what the trigger is, a referral to an allergist can be helpful for identifying what needs to be avoided. However, most IgE responses are quite apparent as they are fairly immediate. When the trigger is easily identified, then the plan of action is simple education about what to avoid, cross-sensitivities, and utilization of life-saving measures in the event of unintentional exposure. One of my other pediatric clients with a significant peanut allergy was told they need to avoid anyone who has consumed peanuts in the last 12 hours, and need to consider this as they grow older and develop more intimate relationships. This hasn't been a guideline I've found in the literature, but something to consider.
When you have a tree nut allergy, you may need to use injectable epinephrine or take an oral #antihistamine. Unlike other common food allergies, you are less likely to outgrow a tree nut allergy, especially if you are a bit more prone to reactions, have eczema or asthma.
References
Bastiaan-Net, S., Reitsma, M., Cordewener, J. H. G., van der Valk, J. P. M., America, T. A. H. P., Dubois, A. E. J., van Wiik, R. G., Savelkoul, H. F. J., de John, N. W., & Wichers, H. J. (2019). IgE cross-reactivity of cashew nut allergens. International Archives of Allergy and Immunology, 178(1), 19-32. doi: https://doi.org/10.1159/000493100
Ertugrul, A., Bostanci, I., & Ozmen, S. (2021). A remarkable food allergy in children: cashew nut allergy. Turkish Arch Pediatrics, 56(2), 131-135. doi: 10.5152/TurkArchPediatr.2020.20111