Food allergies are among the allergies that many people fear most. Media reports about allergic reactions after consuming peanuts have certainly contributed to this. However, extreme consequences such as shortness of breath or even anaphylactic shock caused by food allergies are relatively rare.
In most cases, the allergy manifests through symptoms such as swollen and itchy mucous membranes, digestive problems, or a skin rash. Naturally, even suspected food allergies should be medically evaluated, as those affected often need to change their diet.
In this article, we discuss food allergies, their consequences, and possible treatments. Naturally, this cannot replace medical care, and you should always consult a doctor you trust if you think you may have a food allergy.
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Typical symptoms of food allergies
The symptoms of a food allergy appear on the skin and mucous membranes, as digestive problems, or through breathing problems. A combination of different symptoms is also possible.
Initial allergy symptoms may occur a few minutes after contact with the triggering food or may not appear until several hours later. The intensity of the reaction may be related to the severity of the food allergy and the amount of allergens consumed.
In the case of a mild food allergy, consuming small amounts may sometimes cause no noticeable reaction. For example, someone with a mild allergy to legumes will probably not notice anything after eating one or two peas in a vegetable casserole.
The mucous membranes are where symptoms of food allergies most commonly appear. The oral mucous membranes are affected in particular, as they came into direct contact with the allergen during eating.
An unpleasant tingling and itching affects the throat and palate. Swelling of the oral mucous membranes is also possible. These symptoms occur immediately after contact with the allergen - for example, a few minutes after eating an apple.
The digestive tract can react to allergens with nausea, abdominal pain, diarrhea, and vomiting, and the symptoms subside once the substances concerned have been completely eliminated.
The airways can also be affected, often in connection with swelling of the mucous membranes in the mouth. Irritating cough, hoarseness, or an audible wheezing sound when breathing are possible signs, although they can of course also have many other causes. If these symptoms occur in the hours after eating a particular food, they may indicate an allergy.
In rare cases, a food allergy can cause such severe swelling of the airways that acute shortness of breath occurs.
Shortness of breath or anaphylactic shock reactions caused by food allergies are relatively rare. However, when they occur, they can be life-threatening. As a general rule, you should not hesitate to seek medical help for any breathing problems. In the event of shortness of breath or asthma attacks, emergency services should be called, because even an acute allergic attack can be quickly stopped with emergency medication.
Once a severe food allergy has been diagnosed, those affected can carry special emergency allergy kits to help themselves in an emergency. The active ingredient epinephrine can be injected directly into the thigh using an applicator with a needle, allowing the adrenaline it contains to take effect immediately and counteract an allergic shock.
Why do food allergies occur?
In a food allergy, the immune system attacks certain proteins contained in food and mistakenly classified as harmful. In the vast majority of cases, allergic symptoms are caused by so-called immunoglobulins (IgE) . These are antibodies whose actual function is to defend against viruses, bacteria, and other harmful substances.
They trigger the typical symptoms of food allergies described above. In rare cases, an allergic reaction occurs without IgE production, which is primarily manifested by intestinal complaints.
Food allergies are to be distinguished from food intolerances. Autoimmune diseases or disorders of the digestive system can also cause symptoms similar to those of food allergies. Lactose intolerance develops, for example, when lactose is not metabolized properly.
Celiac disease , on the other hand, is an autoimmune disease in which the immune system is prompted by the ingestion of gluten to attack the body's own cells. However, it is not a food allergy.
In some cases, toxic reactions cause symptoms that may resemble allergies. For example, if food contains mold spores, they can cause vomiting, diarrhea, or symptoms of poisoning. Boiling does not make mold harmless.
Common food allergy triggers
The following foods and food ingredients are known as common triggers of food allergies and food intolerances and must be identified by law on packaging. Stores that sell the relevant foods unpackaged must also provide information about possible allergies.
- Eggs
- Peanuts
- Fish
- Crustaceans
- Lupins
- Milk
- Tree nuts
- Celery
- Mustard
- Sesame seeds
- Sulfites (preservatives in dried fruit or wine)
- Wheat, rye, oats, and other gluten-containing grains
Among the allergy triggers listed above, peanuts, tree nuts, wheat, chicken eggs, and milk cause the most allergies. When it comes to milk, it can happen that a lactose intolerance is mistaken for an allergy .
True allergies to milk protein occur primarily in early childhood, but usually subside within a few years. Milk allergy is very rare among adults. A food allergy to tree nuts or peanuts, on the other hand, can persist for life.
Peanuts in particular are known to cause severe allergic reactions even in small amounts.
In general, food allergies that do not subside by puberty also remain active in adulthood. In addition, some food allergies do not develop until adulthood. Examples include allergies to fish or shellfish, which are extremely rare among children. Wheat allergies also often do not appear until childhood and adolescence are over.
Cross-allergies between foods and other allergens
People who are allergic to foods can theoretically develop a cross-allergy to certain types of pollen . Conversely, people with pollen allergies sometimes react to certain foods. The birch tree is the most prominent example of cross-allergies involving foods. People who react allergically to its pollen are often also allergic to apples or other fruit.
When birch pollen is in the air, it often acts as an aggravating factor for these food allergies. This means that you may experience stronger symptoms when eating fruit than usual. Another cross-allergy is the combination of a dust mite allergy and an allergy to crustaceans and shellfish. However, it occurs far less frequently than cross-allergies to pollen. The latex-fruit syndrome is a cross-reaction that can occur in people with a latex allergy when they eat certain types of fruit, vegetables, or nuts.
Other substances can also act as aggravating factors for food allergies. Alcohol consumption or taking certain medications can sometimes intensify the symptoms. Physical exertion or a weakened state caused by an infection could also lead to more severe effects of a food allergy.
Diagnosis and treatment of food allergies
The problem is that the symptoms of a food allergy can resemble those of many other diseases or allergies. The approximately four percent of the population who are allergic to certain foods in this country sometimes struggle with their symptoms for a long time before having them assessed by an allergist. To diagnose food allergies, a combination of different allergy tests is often used, preceded by detailed consultations with the patient.
Prick test: As one of the most reliable skin tests, the so-called prick test (“skin prick test”) is very frequently used to diagnose a wide range of allergies. A drop of liquid containing the allergen being tested is applied to the surface of the skin. The skin is then scratched with a sterile needle through the drop. The allergen can penetrate the tissue, where, in the event of an existing allergy, it will trigger a reaction within a short time in the form of redness, swelling, or wheals. A whole range of allergens are often tested simultaneously on previously prepared and numbered areas of skin.
Blood test: If the patient's medical history indicates a severe food allergy with potentially life-threatening consequences, a blood sample can be examined instead. Laboratory testing is completely safe for patients who might otherwise experience strong reactions to a skin test. For example, IgE antibodies can be detected in the blood. However, these can also occur as a result of other conditions, which is why blood samples alone do not always lead to a clear diagnosis of a food allergy.
Provocation test: A provocation test can provide certainty when blood samples or skin tests do not yield sufficient information. However, this test must absolutely be performed under medical supervision because patients consume a small amount of the suspected allergen. For example, a food is eaten in a very small dose. The allergic reaction during the provocation test can be very severe - however, under supervision in an allergy clinic, immediate countermeasures can be taken. Understandably, this is not the preferred diagnostic method for food allergies.
Elimination diet: This special diet usually accompanies the diagnosis to confirm the results obtained from skin and blood tests. The foods concerned are completely “eliminated” from the daily diet for several weeks. Once the suspected allergens have been excluded for long enough, a targeted provocation test is performed under medical supervision. If the food allergy is confirmed, the elimination diet can serve as a basis for permanently changing the diet.
Once a food allergy has been confirmed, targeted measures can be taken to avoid the allergen in the future. Medication can only provide short-term solutions for treating severe symptoms. In the long term, the diet must be adjusted under medical supervision so that the allergens are completely avoided.
In children and adolescents some food allergies resolve over time. Their immune system learns to tolerate the “foreign” proteins. Allergies to milk, soy, or wheat, for example, are known to often weaken or disappear completely during childhood. It therefore makes sense to repeat allergy tests in children and adolescents from time to time. When adults develop an allergy to a particular food, the immune system generally no longer learns tolerance. Food allergies that develop in adulthood are rare but usually permanent.
Food supplements as a way to compensate for food allergies
Some foods can be avoided without difficulty – nuts or seafood, for example, are not necessary to guarantee a balanced diet. The situation is different for foods that provide important vitamins, magnesium, folic acid, and other urgently needed nutrients .
Eliminating dairy products without replacing them can also lead to deficiency symptoms – this would be especially concerning in growing children. Sick or older people may even require an increased amount of certain nutrients.
Food supplements can be particularly helpful when switching to a new diet, helping to maintain an adequate supply of urgently needed minerals and vitamins. Omega-3 fatty acids found in fish, as well as in some seeds and nuts, are an example of food supplements that can be taken in the form of pills or effervescent tablets.
It is best to discuss the possible use of this treatment as part of treating a food allergy with your doctor.
Desensitization for a food allergy?
Desensitization as used for hay fever or animal hair allergies is not yet possible for food allergies. Some studies on various food allergies are already quite advanced – however, it will probably take some time before they become approved medical procedures.
As of now (mid-2024), a study in the United Kingdom is underway in which children eat foods they are allergic to under medical supervision. The BBC reported that a boy with a peanut allergy was even able to eat up to six peanuts a day again without symptoms
This method naturally carries the risk of allergic overreactions. There are also no long-term data yet – those affected will probably have to expect to eat small amounts of the allergen regularly for the rest of their lives to maintain the newly acquired tolerance. The success of such studies will first have to be demonstrated over years of successful application.
If you notice symptoms of a food allergy, it is always advisable to seek specialist medical advice. Many general practitioners, pediatricians, dermatologists, or ENT specialists are also allergists. Take your symptoms seriously and seek professional help, because even with a food allergy, it is still possible to live well once it has been diagnosed.
