Once you learn foods that you are allergic or intolerant to, try to avoid them. Practice reading labels when shopping and asking about ingredients when eating out. Work with your healthcare provider at having a plan of action in case of a reaction and make sure to inform family and friends what to do in these situations. Stay aware of symptoms and do not take them lightly. To prevent the development of food allergies or intolerance, eat a balanced diet and ensure that you are not eating an excess of one particular kind of food.

Adults do not usually stop having allergies. Children can sometimes outgrow milk or soy allergies; they rarely outgrow allergies to peanuts or seafood. If you have a very serious allergic relation to certain foods it is best to never reintroduce them into your diet. However, if a food is eliminated from the diet for 4-6 months and reintroduced later in small amounts, you may frequently find that you are able to tolerate the food again in moderate amounts.

Sources:  American College of Allergy, Asthma, and Immunology; WebMD