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.