The terms food allergy, food sensitivity and food intolerance are often used interchangeably, but they're not exactly the same. Food intolerance is a reaction to a food or group of foods, while a true allergy triggers an immune system response that can be life-threatening. Since the term “food sensitivity” may be used for either of these conditions, it’s important to understand the difference.
Food Intolerance
"Food intolerance" means that when you eat a particular food, you develop symptoms. The reaction may be delayed by several days, so it is sometimes difficult to determine which food or foods are the offenders. You can have food intolerance for a single food or for all the foods in the group. For example, you may react only to orange juice but still be able to drink lemon juice or grapefruit juice. If you have gluten intolerance, you may need to avoid rye and barley as well as wheat.
Food Intolerance and Health
Food intolerance does not generally cause major health problems but may cause poor absorption of nutrients or vitamin deficiencies if you avoid a group of foods. Symptoms of food intolerance include headaches, gastrointestinal problems, skin irritations, sinus congestion, fatigue and mood changes. If you avoid the food, the symptoms get better or go away entirely. Although the symptoms from food intolerance may make you uncomfortable or prevent you from feeling your best, they are not likely to be fatal.
True Food Allergy
A true food allergy causes an immune reaction. The immune system normally protects us from foreign substances such as bacteria and viruses. Proteins in some foods can cause an exaggerated immune system response by causing an increase in immunoglobulin E, or IgE. If you eat or drink something to which you are allergic, IgE immediately responds and causes symptoms such as swelling of the mouth and throat, difficulty breathing, a sudden drop in blood pressure and loss of consciousness. This condition, called anaphylaxis or anaphylactic shock, can be fatal if not treated immediately.
Cross-Reactivity
Another issue to consider in the case of true food allergies is cross-reactivity. If you have allergies to pollen, you may also be sensitive to certain foods, according to the Mayo Clinic. The proteins in some foods are similar to the proteins in pollens and can trigger IgE release. People who are allergic to birch pollen, for example, may also react to apples, carrots, celery, hazelnuts, peaches and pears. People who are allergic to grasses may react to tomatoes. Cross-reactivity, also called oral allergy syndrome, can trigger anaphylaxis.
Considerations and Warnings
Whether it is called food sensitivity or food allergy, if you react to any food with symptoms of itching, hives, swelling and difficulty breathing, seek immediate emergency medical attention. Anaphylaxis can be fatal within a few minutes if not treated and you may need to carry a treatment kit that contains adrenalin if you have severe food sensitivity, according to the Mayo Clinic.
