Ingredient decoder
Soybean (Gly m 4)
Soybean (Gly m 4) is a birch-pollen cross-reactive food — its PR-10 Proteins protein resembles the birch allergen closely enough that pollen-allergic people can react to it.
Label check
Birch-allergic people occasionally react to soy drinks via the Gly m 4 protein even when they tolerate other soy foods.
Allergen family data
| Family | Category | Severity | Mapping |
|---|---|---|---|
| PR-10 Proteins | pollen_food | Usually mild (oral allergy syndrome) | Curated mapping |
Sources: SleuthIt curated dataset
Also appears as
Cross-reactivity
~70% of birch pollen allergics react to raw apple
~50% of birch allergics react to cherry
Birch-celery-mugwort-spice syndrome
Case notes
On packaging, soy is declared as one word — and that single word covers a range of different soy proteins. Gly m 4, also written as Soy PR-10 or listed under the plant name Glycine max, is one of them, and it almost never appears by name on a label. Parents are far more likely to meet the term on an allergy test report than on an ingredient panel, which makes it hard to connect a specific reaction back to something readable on a package.
The pattern that catches families off guard is inconsistency. Birch-allergic people occasionally react to soy drinks via the Gly m 4 protein even when they tolerate other soy foods. PR-10 proteins are heat-labile and often destroyed during processing, though they may persist in fresh or minimally processed products. So the useful detail isn't just whether "soy" appears in the ingredients — it's the form the soy takes, and how much processing it has been through. Two products that both list soy can behave very differently.
Gly m 4 sits in the PR-10 protein family, the pollen-related group that also includes apple, cherry, celery, hazelnut, carrot and peach. The shared thread is birch pollen: roughly 70% of birch pollen allergics react to raw apple, about 50% to cherry, and celery features in birch-celery-mugwort-spice syndrome. Reactions in this family are usually mild, in the oral allergy syndrome range. Noting the specific product, its form, and the time of year alongside symptoms gives you a much clearer record than the word "soy" alone.
Questions
Soybean (Gly m 4) is a birch-pollen cross-reactive food — its PR-10 Proteins protein resembles the birch allergen closely enough that pollen-allergic people can react to it.