Objective To explore food intolerance (FI) characteristics and its relationship with Helicobacter pylori (Hp) infection in chronic gastritis (CG) patients of different age groups. Methods Patients admitted to a hospital from August 2021 to August 2022 were selected as the study subjects. According to age, patients were divided into the young-middle-aged group and the elderly group. According to whether Hp infection occurred, they were divided into the infection group and non-infection group. Clinical data and 14 food allergen specific immunoglobulin G (IgG) levels of patients were collected. Testing results were analyzed by statistical software, risk factors were analyzed by multivariate logistic regression, and predictive value of the model was evaluated. Results A total of 108 CG patients were admitted to the hospital, with 65 males and 43 females. There were 78 cases (18-64 years old) in the young-middle-aged group and 30 (≥ 65 years old) in the elderly group, 60 cases in the Hp infection group and 48 cases in the non-infection group. The total positive rate of FI tests of 14 kinds of food was 56.48% (61/108). Five food types with highest FI positive rates were shrimp (44.44%), egg (40.74%), crab (35.19%), soybean (31.48%), and cod (29.63%); five food types with highest FI positive rates in the young-middle-aged group were egg (46.15%), shrimp (38.46%), soybean (37.18%), cod (32.05%), and crab (29.49%); in elderly group, they were shrimp (60.00%), crab (50.00%), chicken (33.33%), rice (33.33%), and egg (26.67%). The FI positive rates for 6 food types (crab, egg, milk, shrimp, soybean, and wheat) in patients of different age groups were compared, and the differences were all statistically significant (all P < 0.05). Compared with Hp non-infection group, the infection group had higher proportions of patients under 65 years old, male, smoking, and higher IgG antibody levels, differences were all statistically significant (all P < 0.05). FI positive rates in the infection group and non-infection group were 65.00% and 45.83%, respectively. Difference between the two groups was statistically significant (χ²=3.985, P=0.046). FI positive rates for 6 food types (cod, crab, egg, mushroom, milk, and shrimp) in the two groups of patients were compared, and differences were all statistically significant (all P < 0.05). After adjusting patient factors as age, gender, and smoking, seafood and non-seafood FI were risk factors for Hp infection (all P < 0.05). The receiver operator characteristic (ROC) curve of the predictive model presented a high accuracy. Conclusion FI is generally present in CG patients, and FI is related to age. The FI test results can provide guidance for patient's diet and reduce the risk of food adverse reactions. Hp infection can easily induce FI, which can increase the risk of Hp infection.