All new born babies living in the city of Oulu are recruited to the study (n=1380) at their first health nurse visit (at or before 1 month of age) in the local primary care child health clinics. Families in the intervention group will get an instruction booklet including information on early systematic introduction of solid foods starting at the age of 4 months, with foodstuff from all major groups in diet by the age of 6 months (vegetables and fruits, wheat and other grains, meat, fish, egg, dairy products). Furthermore, the booklet includes information and instructions on food related symptoms and atopic eczema. Babies with mild symptoms are encouraged to continue the symptom-eliciting food. All families fill out monthly internet-based questionnaires on food diary, symptoms, diagnoses and health care visits until the age of 1 year.