What’s the difference between a food allergy, intolerance, and sensitivity? A food allergy is an immediate reaction to a specific food that occurs every time you eat it. This immune response causes your body to recognize the food as a foreign substance and work to attack it. Peanut, egg, milk, and wheat allergies are among the most common. Food intolerances are different from food allergies in that they don’t trigger an immune response. Instead, the body experiences difficulty digesting certain foods, causing symptoms such as gas, bloating, and diarrhea. This often results from the lack of proper enzymes required to break down foods in the body. Food sensitivities are delayed reactions to food that appear several hours or even days later. These responses are hard to distinguish, cause vague symptoms, and can go undiagnosed for years. While many factors contribute to food sensitivities, they most frequently stem from the inability to digest and absorb nutrients.