There are very few population-based studies investigating the incidence of food hypersensitivity during the first year of life.

To determine the incidence of parentally reported food hypersensitivity and objectively diagnosed food hypersensitivity during the first year of life.

A birth cohort was recruited (n = 969). At 3, 6, 9, and 12 months, information regarding feeding practices and reported symptoms of atopy were obtained. At 1 year, infants underwent a medical examination and skin prick testing to a battery of allergens. Symptomatic infants underwent food challenges.

Adverse reactions to foods were reported by 132 (14.2%) parents at 3, 83 (9.1%) at 6, 49 (5.5%) at 9, and 65 (7.2%) at 12 months. Of the subjects, 1.0% (8/763) were sensitized to aeroallergens and 2.2% (17/763) to food allergens. Between 6 and 9 months and 9 and 12 months, 1.4% (14/969) and 2.8% (27/969) infants were diagnosed with food hypersensitivity on the basis of open food challenges and 0.9% (9/969) and 2.5% (24/969) on the basis of double-blind, placebo-controlled food challenges. Cumulative incidence of food hypersensitivity by 12 months was 4% (39/969; 95% CI, 2.9% to 5.5%) on the basis of open food challenges and 3.2% (31/969; 95% CI, 2.2% to 4.5%) on the basis of double-blind, placebo-controlled food challenges.

Between 2.2% and 5.5% of infants have food hypersensitivity in the first year of life. The rate of parental perception of food hypersensitivity is higher than the prevalence of atopic sensitization to main food allergens or objectively assessed food hypersensitivity.

In the first year of life, the rate of parentally perceived food hypersensitivity is considerably higher than objectively assessed food hypersensitivity.