Increasing evidence indicates that intestinal microecological imbalances are strongly associated with food allergen intolerance. This study investigated the effect of olive oil on food allergy susceptibility and intestinal microecology based on an ovalbumin (OVA)‐sensitized mouse model. The results indicated that the allergic symptoms of sensitized mice were alleviated when they were supplemented with olive oil at 1–3 g/kg per day for 7 weeks. Intestinal epithelium observation showed repaired ileum villi and upregulated tight junction (TJ) protein expression. Furthermore, the levels of the cytokines (e.g., IL‐10) secreted by regulatory T cells were increased, whereas T helper 2 (Th2) cell‐associated factors were decreased in lamina propria. Furthermore, 16S rRNA sequencing indicated reduced Burkholderiaceae and increased Clostridiaceae in the intestinal microflora. The results suggest that an olive oil‐enriched diet may effectively prevent food allergies by regulating the intestinal microecological balance. Practical applications Recent studies emphasized that intestinal ecological imbalance, including intestinal immunity and microflora structure, plays an important role in affecting the occurrence and development of food allergy. The present results implied that olive oil, one of the main components of the Mediterranean diet, can effectively ameliorate the symptoms of OVA‐induced food allergy by regulating intestinal microecological homeostasis. Therefore, dietary supplementation with olive oil may be an effective strategy for preventing food allergies.

Scope This study assesses whether oleuropein prevents ovalbumin (OVA)‐induced food allergy (FA) and investigates the underlying mechanisms. Methods and results A Balb/c FA mouse model is established and maintained for 7 weeks. The subjects are administered OVA by oral gavage to induce FA and supplemented with different oleuropein doses (1.00–20.00 mg kg−1 per day) to evaluate its preventative efficacy. The results indicate that oleuropein effectively alleviates OVA‐induced allergy symptoms and promotes temperature elevation in sensitized mice. The secretion of serology‐specific OVA‐immunoglobulin (Ig)E, OVA‐IgG, and histamine is inhibited in the sensitized mice. Oleuropein dramatically upregulates the expression of intestinal tight junction (TJ) proteins, regenerating gene (Reg) IIIγ, and interleukin (IL)‐22, enhancing the physical and biochemical barrier function of the intestinal epithelium. Additionally, oleuropein improves the immune homeostasis of the intestinal epithelium by affecting the function of mucosal mast cells and regulatory T (Treg) cells. The disordered intestinal flora of the sensitized mice also improves after oleuropein administration. Conclusions These findings suggest that oleuropein prevents FA by enhancing intestinal epithelial barrier function and improving immune homeostasis and intestinal flora in sensitized mice. Therefore, diets rich in oleuropein should be recommended for people with FA.