Can oral allergy syndrome develop in adulthood?

Oral Allergy Syndrome Can Develop in Adulthood

Yes, oral allergy syndrome (OAS) can definitely develop in adulthood, as food allergies starting in adult life often result from de novo sensitization to allergens encountered after childhood and tend to be persistent. 1

What is Oral Allergy Syndrome?

Oral Allergy Syndrome (also known as pollen-food syndrome) is a type of food allergy resulting from cross-reactivity between pollen allergens and structurally similar proteins in raw fruits, vegetables, and nuts. Symptoms typically include:

• Immediate itching and swelling of the lips, tongue, palate, and throat
• Symptoms usually limited to the oral cavity
• More common in patients with seasonal allergic rhinitis 2

Epidemiology and Risk Factors

Several factors contribute to the development of OAS in adults:

• Increasing age: In contrast to food allergies, reactivity to aeroallergens increases with age 1
• Prior sensitization: OAS occurs in patients with a prior cross-reactive aeroallergen sensitization 3
• Gender: OAS is more frequent in female patients than male patients 4
• Comorbid allergic conditions: More prevalent in patients with:
  • Allergic rhinitis and asthma
  • Allergic rhinitis and atopic dermatitis 4
• Higher total IgE levels: Associated with increased risk 4

Pathophysiology

OAS develops through a specific immunological mechanism:

1. Initial sensitization to pollen allergens (commonly birch, grass, or ragweed)
2. Development of IgE antibodies that cross-react with structurally similar proteins in certain foods
3. Cross-reactivity triggers symptoms upon food consumption

The underlying pathophysiology affects clinical presentation depending on whether the cross-reactive protein is:

• A heat-labile PR-10 protein
• A partially labile profilin
• A relatively heat-stable lipid transfer protein 3

Common Triggers

Common food triggers vary by geographic region and pollen sensitization patterns:

• Classic triggers: Apple (68%), peach (56%), nuts (36%), kiwi (20%), persimmon (20%), plum (16%), and cherry (16%) 5
• Regional variations: In Korea, unique triggers include Chinese yam, kudzu vine, bellflower root, codonopsis, and ginseng 5
• Most patients (60%) react to three or more foods simultaneously 5

Diagnosis

Diagnosis of OAS in adults involves:

1. Clinical history: Symptoms occurring immediately after consuming raw fruits/vegetables in patients with known pollen allergies
2. Skin testing: Fresh food skin prick tests typically have the highest sensitivity 3
3. Specific IgE testing: Can help identify cross-reactive allergens
4. Oral food challenges: Gold standard for confirming diagnosis in uncertain cases 1

Management Approach

Management of OAS in adults includes:

1. Avoidance strategies:

   • Avoid raw trigger foods
   • Consider cooking or processing foods (heat often denatures the allergenic proteins)
   • Be cautious with concentrated forms like smoothies, juices, and nutritional supplements 6

2. Medication:

   • Consider antihistamines before consuming known trigger foods if they cannot be avoided
   • Second-generation H1 antihistamines (cetirizine, loratadine, fexofenadine) are preferred due to reduced sedation 2
   • For severe reactions, epinephrine autoinjectors may be necessary 2

3. Immunotherapy:

   • Standard immunotherapy for pollen allergies may help OAS symptoms in some cases, though evidence is mixed 2

Risk of Severe Reactions

While OAS is typically considered mild:

• 8.7% of patients may progress to systemic symptoms outside the gastrointestinal tract
• 1.7% may experience anaphylactic shock 3
• Risk factors for severe reactions include:
  • Coexisting asthma
  • Consumption of concentrated forms of trigger foods (smoothies, juices)
  • Certain types of cross-reactive proteins (especially lipid transfer proteins) 2, 6

Key Considerations for Adults

• OAS in adults tends to be persistent, unlike many childhood food allergies that resolve with age 1
• Adults with OAS should be properly advised about the potential for severe reactions with concentrated forms of plant foods 6
• Seasonal patterns should be considered, as symptoms may worsen during relevant pollen seasons 1
• Adults with multiple allergic conditions (asthma, atopic dermatitis) may be at higher risk for developing OAS 4

OAS is an increasingly recognized condition in adults, requiring proper diagnosis and management to prevent complications and maintain quality of life.