Legume allergies more common among children with multiple food allergies
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Legume allergies appeared more common among children with multiple food allergies, and most of these children were allergic to multiple legumes, according to a study conducted in Turkey and published in Pediatric Allergy and Immunology.
Also, lip dose challenges (LDCs) with paste appear promising in predicting oral food challenge outcomes, Elif Soyak Aytekin, MD, of the department of pediatric immunology at Hacettepe University Faculty of Medicine in Ankara, Turkey, and colleagues wrote in the study.
The study examined 87 children (median age, 4.9 years; 78% boys; median age at allergy onset, 19 months) followed for legume allergy in the pediatric allergy division at Hacettepe University Ihsan Dogramaci Children’s Hospital between Jan. 1, 2015, and Sept. 30, 2021.
The population included 78 children (90%) with a history of atopic comorbidity, including 70% with atopic dermatitis, 40% with asthma and 30% with allergic rhinitis. Also, 92% were allergic to two or more food groups, including 71% to tree nuts, 67% to hen’s egg, 49% to cow’s milk and 46% to seeds.
Lentil (66%) was the most frequently diagnosed legume allergy, followed by peanut (61%), chickpea (28%), pea (24%), bean (8%) and soybean (1%), with 60% of children experiencing two or more legume allergies.
The children in the study experienced 163 allergic reactions, including 58 with urticaria, 38 with anaphylaxis, 26 with exacerbation of eczema and 18 with angioedema. The highest frequencies of anaphylaxis were produced by lentils among 34% of children and by peanuts among 32%.
Of the 57 children reactive to lentils, 47 had a consistent history of reactions, 10 had their allergy proven by oral food challenge and 48 had multiple legume allergies. Also, 41% were co-allergic to chickpeas and peanuts, 36% were co-allergic to peas and 58% were co-allergic to tree nuts.
The 53 children allergic to peanuts included 51 who had a consistent history of reactions and two with a positive OFC. This subset also included 49% with multiple legume allergies and 23% who had an anaphylactic reaction to peanuts. Co-allergies included 43% to lentils, 28% to chickpeas and 87% to tree nuts.
All 24 children with chickpea allergy, which included 21 with consistent history and three with a positive OFC, had multiple legume allergies including 96% to lentils, 63% to peas, 63% to peanuts and 58% to tree nuts.
Next, 16 of the 21 children with pea allergy had a consistent history, and five had a positive OFC. All also were allergic to lentils, with 71% allergic to chickpeas, 52% allergic to each peanuts and tree nuts.
Six of the seven patients with a bean allergy had a consistent clinical history, and one had a positive OFC. All of these patients had multiple legume allergies and a co-allergy to lentil, while five each also had peanut and chickpea allergies.
Only one patient, however, had a soybean allergy with a consistent clinical history.
Researchers performed LDCs 30 minutes before the OFC to 33 patients. Nineteen patients had negative LDCs, with 14 passing the OFC and five failing. Only one of the 14 patients who had a positive LDC passed the OFC, whereas 13 failed.
According to the researchers, LDC had an 81.82% diagnostic accuracy, 72.22% sensitivity, 93.33% specificity, 92.86% positive predictive value, 73.68% negative predictive value, 10.8 positive likelihood ratio and 0.3 negative likelihood ratio.
Although considered the gold standard for diagnosis, the researchers said, OFC has risks and can be both labor and time consuming. But the standardized use of LDC paste, they continued, could identify patients at risk for more severe reactions and reduce the number of OFCs needed.
Perspective
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This study is from Turkey, where the diet is very different from the United States. Its specific numbers, prevalence and co-allergy do not translate to the U.S. diet. For example, the lupine is a fairly allergenic bean that is not that common in the U.S. diet, so we do not hear about it as much. They don’t eat it in Turkey apparently either. Obviously, we hear about allergy to peanut, which also is a bean, all the time in the U.S. But we hear much less about lentil, unlike Turkey.
Having said that, ultimately, this study mostly confirmed information in other studies regarding the potency of beans regarding allergy. Other articles on this topic have found that:
- Peanut is a bean, but most people with peanut allergy (approximately 95%) tolerate other beans.
- If a person is allergic to “other beans,” the triggers are usually among chickpea, lentil, green pea (and its varietals) and soy, and not common for string bean, white bean, lima, kidney or black bean.
- If a person is showing allergy to some beans among the ones listed as “usually” above, then allergy to more than one among them is also possible. People with broader ranges of food allergies are more likely to see this happen.
- It is also possible to be allergic to one type of bean and no others, such as just lentil or just peanut.
- The amount of bean eaten, or how it is processed, may influence allergy. Some people may tolerate tofu and other soy products, but “soy protein isolate” or “soy protein concentrate” may over-represent certain proteins where the person does react.
Similarly, many of the new artificial meat products or high protein foods supplemented with pea protein (often a yellow, dung or farmer pea) have high concentrations that may trigger a reaction even in someone who usually eats peas with mixed vegetables, because there is more protein.
Another example could be a person who eats edamame but reacts to soy milk, which has more protein, or who eats peas but reacts to pea soup, which also has more protein.
If a person reacts to a bean with allergy symptoms — beans cause gas and bloating, which is not allergy — the allergist should ask about how much was eaten, what other beans the patient eats and related questions. It is very likely that patients can eat many types of beans even if they are allergic to one or a few types.
Talking to an allergist to make sure a person is not over-avoiding is very important. It also is important for patients to understand if they need to be careful about specific food products with concentrated pea or if other bean proteins are a concern, so that should be part of the discussion too.
Perspective
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This retrospective study of children with legume allergy in Turkey showed higher rates of co-allergy with legumes and other foods than previous studies. As the authors mentioned, there is good prior evidence that there are regional differences in the prevalence of legume allergy and in patterns of sensitization.
In my own experience, I have found high rates of co-allergy between lentil, chickpea and pea, but have seen lower rates of co-allergy with peanut than found in this study. I have also seen lower rates of co-allergy with nonlegumes.
As mentioned, there are known regional differences in legume allergy and, therefore, providers outside of this region should not change practice based on these results.
Although this study provides good information, allergy was primarily diagnosed based on clinical history and not food challenge outcomes, which could have impacted the results. A potential next step in research would be a longitudinal cohort study that follows children from an early age to determine onset of legume allergy and to confirm allergies with oral food challenges.
For more information, Scott H. Sicherer, MD, FAAP, author of the above perspective, was the coauthor of a good study of cross-reactivity in food allergy including legumes.
Reference:
Cox AL, et al. J Allergy Clin Immunol Pract. 2020;doi:10.1016/j.jaip.2020.09.030.
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