What is a food allergy?
A food allergy is an immune system reaction. The condition is caused when the body mistakes an ingredient in food (usually a protein) as harmful and creates a defense system (antibodies) to fight it. An allergic reaction occurs when antibodies fight an "invading" food protein. The most common food allergies are shellfish, tree nuts, fish, eggs, peanuts and milk.
What is a food intolerance?
Food intolerances are digestive system reactions, not immune system reactions. It occurs when something in the food irritates a person's digestive system or when a person is unable to digest or break down food properly. Lactose intolerance, found in milk and other dairy products, is the most common food intolerance.
How common are food allergies and intolerances?
Food allergies affect approximately 1% of adults and 7% of children, although some children have outlived their allergic reactions. Food intolerances are more common. In fact, almost everyone has had an unpleasant reaction to something they ate. Some people have specific food intolerances. Lactose intolerance is the most common specific food intolerance, affecting approximately 10% of Americans.
How to differentiate between food allergies and intolerances?
Food allergies can be triggered by even small amounts of food and can occur every time food is eaten. People with food allergies are generally advised to avoid these problematic foods entirely. Food intolerances, on the other hand, are often dose-related. People with food intolerances may not experience symptoms unless they eat most of the foods or eat them regularly. For example, a person with lactose intolerance may be able to drink milk with coffee or a glass of milk, but will get sick if he or she drinks several glasses of milk. Food allergies and intolerances are also different from food poisoning, which is usually caused by spoiled or contaminated food and affects more than one person eating that food. Your healthcare provider can help determine if you have an allergy or intolerance,
symptoms and causes
What are the symptoms of food allergies?
Symptoms of food allergies range from mild to severe, and the amount of food needed to trigger a reaction varies from person to person. Symptoms of food allergy may include:
- rash or hives
- nausea
- Crampy stomach pain
- diarrhea
- itchy skin
- Shortness of breath
- chest pain
- swelling of the airways into the lungs
Anaphylaxis is a very serious and potentially fatal allergic reaction involving a sudden drop in blood pressure, loss of consciousness, and collapse of body systems.
What are the symptoms of food intolerance?
Symptoms of food intolerance include:
- nausea
- stomachache
- Gas, cramping, or bloating
- Vomit
- Heartburn
- diarrhea
- Headache
- irritable or nervous
What causes food allergies and intolerances?
Food allergies result from sensitivity to compounds in food, even compounds that occur naturally in food. Food allergies are more common in people who have family members with allergies, suggesting that hereditary or hereditary factors may be involved in the development of food allergies.
Food allergies occur when you are exposed to food proteins that your body deems harmful. The first time you eat a food containing protein, your immune system responds by producing specific disease-fighting antibodies called immunoglobulin E or IgE. When you eat that food again, it triggers the release of IgE antibodies and other chemicals, including histamine, in an effort to expel the protein "invaders" from your body. Histamine is a powerful chemical that can affect the respiratory system, gastrointestinal tract, skin, or cardiovascular system.
Your allergy symptoms depend on where in the body the histamine is released. If it is released in the ears, nose, and throat, you may experience an itchy nose and mouth, or difficulty breathing or swallowing. If histamine is released in the skin, you may develop hives or a rash. If histamine is released in the gastrointestinal tract, you may experience stomach pain, cramps, or diarrhea. Many people experience a variety of symptoms when eating and digesting food.
There are many factors that lead to food intolerances. In some cases—such as lactose intolerance—people lack chemicals called enzymes, which are needed to properly digest certain proteins in food. Intolerances to certain chemical ingredients added to foods to provide color, enhance flavor and prevent bacterial growth are also common. These ingredients include various dyes and MSG, a flavor enhancer.
Substances called sulfites, which may occur naturally - as in red wine - or may be added to prevent mold growth and are the cause of intolerance in some people. The U.S. Food and Drug Administration has banned the use of sulfate sprays to preserve fruits and vegetables, but sulfates still occur naturally in some foods. Salicylates are a group of phytochemicals naturally found in many fruits, vegetables, nuts, coffee, juices, beer and wine. Aspirin is also a compound in the salicylate family. Foods containing salicylates may trigger symptoms in people who are sensitive to aspirin. Of course, any food eaten in excess can cause digestive symptoms.
Diagnosis and testing
How is food intolerance diagnosed?
Most food intolerances are discovered through trial and error to determine which foods or foods cause symptoms. You may be asked to keep a food diary to record what you eat and when you develop symptoms, and then look for common factors. For example, after charting what he ate each day for a month, one man found that he only experienced symptoms on days when he ate cheese. This points the finger to the cheese, which may be the cause of his discomfort.
Another way to identify problem foods is an elimination diet. You start by completely eliminating any suspect foods from your diet until you are symptom-free. Then you start reintroducing foods, one at a time. This can help you determine which foods are causing your symptoms. Before starting an elimination diet, seek the advice of your healthcare provider or registered dietitian to ensure your diet provides adequate nutrients.
management and treatment
How are food intolerances treated?
Treatment is based on avoiding or reducing the intake of problem foods and treating symptoms when the problem foods are eaten; for example, taking antacids to treat heartburn or stomach pain.
prevention
Can food intolerance be prevented?
Taking a few simple steps can help you prevent symptoms associated with food intolerances.
- Understand which foods are causing your symptoms in amounts and limit your intake to what you can handle.
- When you eat out, ask your server how your meal will be prepared. Certain meals may contain foods you cannot tolerate, which may not be obvious from the description on the menu.
- Learn to read food labels and check the ingredients of problem foods. Don’t forget to check for condiments and seasonings. They may contain MSG or other additives that may cause symptoms.
