People often have an unpleasant reaction to something they ate and think they have a food allergy. But they may be having something else: a reaction called food intolerance.
A true food allergy causes an immune system reaction that affects numerous organs in the body. It can cause a range of symptoms. In some cases, an allergic food reaction can be severe or life-threatening. In contrast, food intolerance symptoms are generally less serious and often limited to digestive problems.
If you have a food intolerance, you may be able to eat small amounts of the offending food without trouble. You may also be able to prevent a reaction. For example, if you have lactose intolerance, you may be able to drink lactose-free milk or take lactase enzyme pills (Lactaid) to aid digestion.
What is a food allergy?
A food allergy is an immune system response. It 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 the antibodies are battling an “invading” food protein. The most common food allergies are shellfish, nuts, fish, eggs, peanuts, and milk.
What is food intolerance?
Food intolerance is a digestive system response rather than an immune system response. It occurs when something in food irritates a person’s digestive system or when a person is unable to properly digest, or break down, the food. Intolerance to lactose, which is found in milk and other dairy products, is the most common food intolerance.
How common are food allergies and intolerances?
Food allergies affect about 1 percent of adults and 7 percent of children, although some children outgrow their allergies. Food intolerances are much more common. In fact, nearly everyone at one time has had an unpleasant reaction to something they ate. Some people have specific food intolerances. Lactose intolerance, the most common specific food intolerance, affects about 10 percent of adult population .
How can you tell the difference between an allergy and intolerance to food?
Food allergies can be triggered by even a small amount of the food and occur every time the food is consumed. People with food allergies are generally advised to avoid the offending foods completely. On the other hand, food intolerances often are dose related; people with food intolerance may not have symptoms unless they eat a large portion of the food or eat the food frequently. For example, a person with lactose intolerance may be able to drink milk in coffee or a single glass of milk, but becomes sick if he or she drinks several glasses of milk. Food allergies and intolerances also are different from food poisoning, which generally results from spoiled or tainted food and affects more than one person eating the food. Your health care provider can help determine if you have an allergy or intolerance, and establish a plan to help control symptoms.
SYMPTOMS AND CAUSES
What are the symptoms of a food allergy?
Symptoms of a food allergy can range from mild to severe, and the amount of food necessary to trigger a reaction varies from person to person. Symptoms of a food allergy may include:
- Rash or hives
- Nausea
- Cramping stomach pain
- Diarrhea
- Itchy skin
- Shortness of breath
- Chest pain
- Swelling of the airways to the lungs
Anaphylaxis is a very serious and potentially fatal allergic reaction that involves a sudden drop in blood pressure, loss of consciousness and body system failure.
What are the symptoms of food intolerance?
The term “food hypersensitivity” refers to both food allergies and food intolerances . A food intolerance is not the same as a food allergy, although some of the symptoms may be similar. In fact, it can be difficult to tell food allergies and food intolerances apart, making it important to speak with your doctor if you suspect you might have an intolerance.
When you have a food intolerance, symptoms usually begin within a few hours of eating the food that you are intolerant to. Yet, symptoms can be delayed by up to 48 hours and last for hours or even days, making the offending food especially difficult to pinpoint . What’s more, if you frequently consume foods that you are intolerant to, it may be difficult to correlate symptoms to a specific food.
While symptoms of food intolerances vary, they most often involve the digestive system, skin and respiratory system.
Common symptoms include :
- Diarrhea
- Bloating
- Rashes
- Headaches
- Nausea
- Fatigue
- Abdominal
pain - Runny nose
- Reflux
- Flushing of the skin
What causes food allergies and intolerances?
Food allergies arise from sensitivity to chemical compounds (proteins) in food, even compounds that are found naturally in food. Food allergies are more common in people whose family members have allergies, suggesting a genetic — or hereditary — factor may be involved with the development of food allergies.
Food allergies develop after you are exposed to a food protein that your body thinks is harmful. The first time you eat the food containing the protein, your immune system responds by creating specific disease-fighting antibodies (called immunoglobulin E or IgE). When you eat the food again, it triggers the release of IgE antibodies and other chemicals, including histamine, in an effort to expel the protein “invader” from your body. Histamine is a powerful chemical that can affect the respiratory system, gastrointestinal tract, skin or cardiovascular system.
The allergy symptoms you have depend on where in the body the histamine is released. If it is released in the ears, nose and throat, you may have an itchy nose and mouth, or trouble 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 likely will develop stomach pains, cramps or diarrhea. Many people experience a combination of symptoms as the food is eaten and digested.
There are many factors that may contribute to food intolerance. In some cases — as with lactose intolerance — the person lacks the chemicals, called enzymes, necessary to properly digest certain proteins found in food. Also common are intolerances to some chemical ingredients added to food to provide color, enhance taste and protect against the growth of bacteria. These ingredients include various dyes and monosodium glutamate (MSG), a flavor enhancer.
Substances called sulfites, which may occur naturally — as in red wines — or may be added to prevent the growth of mold, also are a source of intolerance for some people. Salicylates are a group of plant chemicals found naturally in many fruits, vegetables, nuts, coffee, juices, beer and wine.Of course, any food consumed in excessive quantities can cause digestive symptoms.
Causes of food allergy
Peanuts, tree nuts, eggs, milk, wheat, sesame, fish, shellfish and soy cause about 90 per cent of food allergic reactions. Peanut allergy is one of the most common allergies in older children as only approximately one in four children will outgrow peanut allergy.
Causes of food intolerance
- Absence of an enzyme needed to fully digest a food. Lactose intolerance is a common example.
- Irritable bowel syndrome. This chronic condition can cause cramping, constipation and diarrhea.
- Sensitivity to food additives. For example, sulfites used to preserve dried fruit, canned goods and wine can trigger asthma attacks in sensitive people.
- Recurring stress or psychological factors. Sometimes the mere thought of a food may make you sick. The reason is not fully understood.
- Celiac disease. Celiac disease has some features of a true food allergy because it involves the immune system. Symptoms often include gastrointestinal issues as well as those unrelated to the digestive system, such as joint pain and headaches. However, people with celiac disease are not at risk of anaphylaxis. This chronic digestive condition is triggered by eating gluten, a protein found in wheat and other grains.
The foods that tend to cause intolerance reactions in sensitive people include:
- dairy products, including milk, cheese and yoghurt
- chocolate
- eggs, particularly egg white
- flavour enhancers such as MSG (monosodium glutamate)
- food additives
- strawberries, citrus fruits and tomatoes
- wine, particularly red wine
- histamine and other amines in some foods.
If you have a reaction after eating a particular food, see your doctor to determine whether you have a food intolerance or a food allergy.
If you have a food allergy, you may be at risk of a life-threatening allergic reaction (anaphylaxis) — even if past reactions have been mild. Learn how to recognize a severe allergic reaction and know what to do if one occurs. You may need to carry an emergency epinephrine shot for emergency self-treatment.
If you have a food intolerance, your doctor may recommend you to take a Food Intolerance Blood test to find out what foods tiger reaction and recommend the steps to aid digestion of certain foods or to treat the underlying condition causing your reaction.