The aim is to study whether a multiallergen oral immunotherapy (OIT) strategy with slow up-dosing and low treatment dose against food allergy in young children (0.5-3 years) is safe and effective, a method to cure food allergy and to prevent the development of new food allergies.

Clinical randomized controlled (1:1) blinded interventional trial (RCT) with 2 intervention arms (group A and B).

Among 80 children reacting at the multiallergen food challenge, 40 children will be randomized to receive OIT (oral immunotherapy) with multiallergen powder with a final dose of approximately 200 mg protein of each included food (egg, milk, soy, wheat, walnut, peanut, hazelnut, cashew, almond, lentils)(group A) or to receive placebo powder (gluten-free oatmeal) (group B).

A sub-analysis will be performed of the children not reacting to the baseline challenge, who will be randomized to eat a low dose of the multiallergen powder (group C) or placebo powder (gluten-free oatmeal) (group D) and no specific advice.

Today, there is no established curative treatment for food allergies, and those affected must avoid the food that triggers symptoms. The most studied method is oral immunotherapy (OIT) which have mainly been carried out on children >4 years of age. The OIT method implies that the allergic individual eats initially very low doses and gradually increasing amounts of the allergen until a maintenance dose is reached. The treatment aims to induce desensitization or tolerance to the allergen.

Intervention: The intervention substance is a powder containing a prespecified amount of 10 allergens (egg, milk, wheat, lentils, soy, walnut, peanut, hazelnut, cashew, almond), which are the most triggering allergens in children. The product is developed in cooperation with Research Institute of Sweden (RISE).

Clinical randomized controlled (1:1) blinded interventional trial (RCT) with 2 interventions arms (group A and B). A sub-analysis will be performed of the children not reacting to the baseline challenge (group C and D).

Group A: Children with food allergy (sensitization and positive baseline challenge), receiving multiallergen powder OIT, slow up-dosing until 3 teaspoons of the multiallergen powder is reached daily. Food challenge will be performed after 1 and 2 years. 2 years treatment.

Group B: Children with food allergy (sensitization and positive baseline challenge), receiving OIT with placebo (gluten-free oatmeal) followed by maintenance, in total 2 years. Food challenge will be performed after 1 and 2 years.

Group C and D: sensitized children with a negative baseline challenge will be randomized 1:1 for treatment with multiallergen powder or placebo powder in a lower amount, 1 teaspoon daily and can introduce food in accordance with Swedish guidelines. After one year a food challenge will be performed.

Selection for group A to D: All children 0.5-3 years of age in Stockholm County who had a positive blood test for suspected food allergy to one or more of the 10 included allergens with specific immunoglobulin E (IgE) >0.1 kUA/L, are eligible as possible study participants. The data is obtained from the Karolinska University Laboratory's test results register. Information letters will be sent to families with IgE-sensitized children.

Inclusion groups A to D: Children 0.5-3 years old at inclusion with positive IgE >0.1 kUA/L against at least one of the 10 above mentioned allergens. Eighty children, group A (n=40) and group B (n=40) also need a positive baseline food challenge.

Children with a negative food challenge (group C and D) (number is not determined) do not react at the baseline challenge.

Primary outcome: Tolerance to 900 mg protein, cumulative dose, of each of the 10 included allergens, at the food challenge after two years OIT treatment or placebo (group A and B).

Secondary outcomes: Tolerance to cumulative dose of 900 mg protein of each food, evaluated with a food challenge after one years in all children (group A-D). Changes in immunological markers, eczema and asthma status and changes in quality of life in relation to interventions.

Inclusion Criteria:

• 0.5-3 years old at inclusion with IgE (>0.1 kUA/l) against at least one allergen (wheat, lentils, egg, milk, soy, walnut, hazelnut, peanut, almond, cashew).
• Written consent for participation in the study for both guardians.
• 80 children (group A and B) also need a positive baseline food challenge.
• Children with a negative food challenge (group C and D) (number not determined) do not react at the baseline challenge.

Exclusion Criteria:

• other serious illness
• previous life-threatening anaphylaxis (intensive care)
• eosinophilic esophagitis
• eosinophilic gastrointestinal disease
• severe chronic gastroesophageal reflux disease
• unclear recurrent GI complaints
• low body weight <2SD
• participation in another intervention study if included in intervention group
• severe uncontrolled asthma
• medication with biological drugs or oral steroids.

The study is blinded and neither participants nor the study team physicians know who is receiving multiallergen powder or placebo. Only few persons outside the study has this knowledge.