Background: The immune system may be modulated with nutrition to prevent the development or to treat the symptoms of allergy. Among other foods, consumption of apples has been linked to reduced incidence of atopic dermatitis and respiratory allergy.

Objective: We evaluated the efficacy and mechanisms of a polyphenol-enriched apple extract in reducing symptoms of food allergy.

Methods: In a model of food allergy to ovalbumin (OVA), BALB/c mice were fed with an apple extract either during sensitization or just before the challenge. After the challenge, allergic symptoms were scored, OVA-specific serum immunoglobulins were determined by ELISA, cytokine production by mesenteric lymph node (MLN) cells was measured by a multiplex assay and gene expression profiles in the intestine were addressed using quantitative real-time PCR.

Results: Consumption of the apple extract reduced symptoms of food allergy upon challenge. This was paralleled by reduced levels of intestinal mast cell protease, diminished cytokine secretion by MLN cells and reduced local intestinal mRNA expression of various T-helper type-2 associated and pro-inflammatory genes. Mechanistic studies suggested decrease of mediator release by effector cells and reduction of allergenicity by protein-polyphenol interaction as potential mechanisms responsible for protection.

Conclusion: Polyphenol-enriched apple extract can attenuate food allergy symptoms in sensitized mice via two distinct possible mechanisms.