Soy Allergy

• Important protein source

• Sensitization frequency varies largely

• Prevalence of soy allergy 0.1-0.4%

• Symptoms– cuteaneous or gastrointestinal– respiratory and systemic reactions

may occur

• Commonly used as additive in foods

Different types of soy allergy

• Genuine soy food allergy– Mostly in small children – Often resolves in childhood

• Soy allergy due to cross-reactivity– Mainly in adults– In birch-related tree pollen

allergic patients – In legume allergic patients

• Occupational allergy

Doctor's challenges

• What kind of soy allergy is it?– Is it a genuine soy allergy or

are the symptoms caused by cross-reactivity?

• Is there a risk for systemic reactions?

• Is strict avoidance necessary?• What dietary advice should be

given?

Genuine or cross-reactive soy allergy?

Common clinical practicePatient

At 4 yearsAnamnesis

SPT to soy SPT to birch

DiagnosisAdvice

Anna

Eczema, Wheeze

+2 +2

Soy and birch allergyAvoid soy

Oliver

Eczema, Wheeze

+2 +2

Soy and birch allergyAvoid soy

Using components in clinical practice

Improved diagnoses and altered advice

Patient

At 4 yearsAnamnesis

SPT to soySPT to birchAt 8 years sIgE to soyGly m 4Gly m 5Gly m 6sIgE to birch

Diagnosis

Advice

Anna

Eczema, Wheeze Milk allergy outgrow+2 +2

0.8 kUA/l

15< 0.1< 0.158

Pollen-associated soy allergy Birch pollen allergy

No need for total avoidance Avoid large amounts of unprocessed soy

Oliver

Eczema, WheezeMilk allergy outgrow+2+2

24 kUA/l

2.516.2 6.7 20

Genuine soy allergyBirch pollen allergy

Strict soy avoidance

Soy components

Soy components

Latin name: Gly m - Glycine max

Gly m 4

Gly m 5Gly m 6

Soy components

Risk assessment of soy components

Gly m 4

• A cross-reactivity marker, associated with allergy to birch and birch-related tree pollens

• A PR-10 protein, homologous

to birch component Bet v 1

• Labile protein - mainly causing local symptoms, e.g. OAS, but systemic reactions may occur

Cross reactivity - birch and soy

Sensitization to soy Gly m 4 likely induced via sensitization to birch

Gly m 5 and Gly m 6

• Are specific marker allergens for soy allergy

• Are storage proteins- proteins expressed in legumes, seeds and nuts

• Stable and heat resistant proteins that may cause systemic reactions

Peanut associated soy allergy

Peanut (f13) 72.1

Ara h 1 22.4Ara h 2 23.1

Ara h 3 13.4Ara h 8 3.7

Ara h 9 <0.1

Boy 15 years old with confirmed peanut and birch allergies. Upon having a Japanese lunch he gets mouth itch.

Soybean (f14) 1.5

Gly m 4 1.9

Gly m 5 1.4Gly m 6 2.2

In conclusion

What does Molecular Allergology add?

• Differentiation between genuine soy allergy and soy allergy due to cross-reactivity

• Enables assessment of the risk for systemic reactions

• Enables more precise dietary advice

Extra slides