Nutrition plays a key role in everyday life. Apart from social, cultural and health aspects, it is also closely linked to enjoyment. But what if this aspect is restricted? If after eating your favourite food you suffer from stomach ache, skin rashes and nausea? According to a study conducted by the German Robert-Koch-Institute, in 30 % of the German adults an allergy was diagnosed. Particularly concerned are adults aged 18-49. In average, allergies seem to increase in Germany. For only 40 %, an allergy test was carried out - thus, 60 % don’t know if they have an allergy or not .
Allergies exist in various forms, one of them being the food allergy. Apart from this, there is the food intolerance. Both cause a great loss in people’s quality of life. Not only the health, but also the social life can be restricted by them. Even meeting friends can - in case of wrong nutrition - thus be linked with stomach pain up to life-threatening allergic reactions. At any time, conscious nutrition is required which asks a lot of knowledge and caution from the people concerned as well as from their families.
In this article, you learn more on food allergies and intolerances - in a compact summary. It also explains the different types of food allergies and how these can be tested.
What is a food allergy?
Allergies are caused by an oversensitive reaction against substances foreign to the body. A food allergy is thus a reaction of the body to a food or food ingredient (antigen). Due to the defensive reaction, the body produces antibodies which react on contact with the allergen (ingredient that causes the allergy). Substances like e.g. histamine are released, which cause the typical allergy symptoms.
The two allergy types
In general, there are immediate type allergies and allergies of the delayed reaction type.
With the immediate type of allergy, the allergy reaction is normally perceived 10-20 minutes after contact with the allergen (e.g. intake of a peanut). However, symptoms are possible after few seconds only as well. In other words: When you eat a peanut, you may feel first symptoms like a “furry” feeling on the tongue shortly after the consumption. 
Another type is the delayed immediate reaction type. In this case, the reaction occurs up to 6 hours after consumption.
The delayed reaction type means that the reaction occurs 6 to 24 hours after contact with the allergen only. Thus, the “furry” feeling on the tongue can be felt only several hours later. 
Nowadays, modern laboratory methods make it possible to reveal by means of a blood test to which foods your body is sensitized i.e. has already produced antibodies. Please check here how a food allergy can be tested.
The process of a food allergy reaction
The process of a food allergy reaction is explained hereunder starting from the consumption to the bodily reaction:
Food allergies are immune reactions
On the first intake of the allergen, e.g. a peanut, no symptoms occur. The body is sensitized for this food. During sensitization, the b cells are activated by intermediation of the so-called TH2 helper cells. The B cells belong to the leukocytes (white cells) which produce the antibodies. This means that only by activation of the B cells through the helper cells, the B cells are able to produce IgE antibodies. The IgE antibodies are released and bind to receptors on the so-called mast cells. Those mast cells contain the histamine which causes the typical allergy symptoms. On renewed contact with the allergen, i.e. second consumption of this food, the IgE mast cells are activated and histamine is released. This causes the allergic reaction which manifests as skin rashes up to headache. [3, 4]Food allergies are immune reactions
What is IgE?
“Ig” stands for immunoglobulin. These are antibodies consisting of protein. They are produced by the body as a defensive reaction towards substances foreign to the body like e.g. bacteria, viruses or plant pollen in the case of hay fever sufferers. These antibodies can be determined by blood testing. This is called a type 1 allergy - also called immediate type allergy. Food reactions are mostly caused by type E immunoglobulins (IgE). They react very specifically with one substance and can be determined exactly in the blood. These immunoglobulins are primarily produced to protect the body against invading organisms (worms or parasites) at the site of penetration.
What are symptoms of a food allergy?
There are various symptoms that can indicate a food allergy or food intolerance. Symptoms vary in strength from hardly noticeable to serious consequences such as allergic shock. The symptoms associated with food allergies can affect the skin, the gastrointestinal tract, the cardiovascular system and the respiratory system. The symptoms occur after contact with the allergen and often within a few minutes only: [2, 5]
- reddening and welts (urticaria)
- stomach ache
- burning sensation in the mouth cavity
- swelling of the mucous membranes and the tongue
- difficulty in breathing up to allergic asthma
- drastic reduction in blood pressure
- allergic shock
Worst case: anaphylactic shock
The allergic shock, also referred to as anaphylactic shock, occurs most often as a reaction to insect stings, drugs or foods and is unpredictable. The release of a large quantity of the messenger substance histamine causes a significant widening of the blood vessels. This leads to a drastic reduction in blood pressure and can, in the worst case, lead to death. As the allergic reaction increases, you should take immediate action when the first mild symptoms appear. Notify the emergency doctor. Until the emergency doctor arrives, place the patient in the shock position (legs out straight and raised). [3, 4]
Good to know: Depending on the severity of the allergy, the allergic shock can be caused by little amounts of the allergen. [3, 4]
Food intolerances can also cause the above described symptoms. In addition, very unspecific symptoms and ailments can appear which can, however, not immediately be associated with the food products. 
What is a cross-allergy?
In case of a cross-allergy, the sensitization can take place for example by airborne allergens such as birch pollen or mugwort pollen. These allergens are present in some foods having a chemically similar structure so that the allergy could also manifests to this food. As antibodies have already been produced against the pollen, the immune system can react already on the first consumption of the food containing the similar allergen. This is called an inhalation allergy.
Inhalation allergies are in 60 % of cases associated with a food allergy (cross-allergy).  Inhalation allergies are caused by airborne allergens. These allergens reach the blood via the lungs and can, this way, lead to an allergy. In young people and adults, cross-allergies are the most common cause for a food allergy. Tree pollen, such as for example birch pollen, are related to an allergy to the following foods:
How high is the risk for cross-allergies within a food group?
People, who are allergic to a certain food can possibly also react to related foodstuffs.
For example: Those, who have an allergy to shrimps, can also react to crab and lobster. Someone, who is allergic to peanuts can have difficulties with tree nuts such as pecan nuts, walnuts, almonds and cashew nuts. In rare cases, they can also have problems with other legumes (apart from soya). 
The following table shows how high the risk for cross-allergies within the foods is 
! Please note: In case you tolerated a foodstuff in the past, that is possibly causing a cross-allergy, you don’t necessarily need to avoid it.
How can I determine a cross-allergy?
Determining a cross-allergy is not easy. In order to learn about the pattern of the cross reaction and what has to be avoided, is one of the reasons why people with food allergies should consult a certified allergist. An allergy test is possibly not specific enough for several foods from the same “family” - these tests are often positive. 
This is why consumption of the food (oral provocation) is the best way to find out whether a certain food causes a reaction. 
The motto is: “The proof of the pudding is the eating.”
Summary: Cross-allergies are achieving an ever increasing importance in the industrial countries. Especially the high risk of a dramatic allergic reaction, like the anaphylactic shock, makes cross-allergies a highly important topic. In case of suspected pollen allergy, you should make an inhalation allergy test in addition to the food allergy test. This test can meanwhile be carried out by means of a simple blood test. Here you can see how you can carry out the Food Reaction Test.
At first glance, a pseudoallergic reaction looks similar to a “normal” food allergy. The difference is that a pseudoallergy is not caused by specific antibodies or sensitized cells. Thus, this type of allergy cannot be determined by measuring the IgE antibodies. The reaction often depends on the specific food consumed. Causative factors are, amongst others, colouring agents and preservatives. 
What causes allergies?
Nowadays, allergies are rightly referred to as a widespread disease. One reason for this is that allergie rates have continuously increased in the past years. An explanatory model, however, is not available to date. However, genetic factors as well as the hygiene hypothesis are being speculated as reasons. For example, aspects as the western lifestyle are seen as a key trigger for allergies.  Apart from this assumption, there are other obvious reasons for the allergies occurring at our latitudes.
People falling ill with an allergy are mostly genetically predisposed (genetic disposition). This means, that the likelihood to develop an allergy is hereditary. However, only the disposition to develop an allergy is inherited and not the allergy to a certain allergen itself. Thus, if one parent suffers from pollen allergy, this can lead to a banana allergy in the child because of the hereditary disposition.  So far, no special genes were identified that are associated with food allergy. 
The hygiene hypothesis: “Dirt prevents allergy”
According to the hygiene hypothesis, the bacteria flora of the gastrointestinal tract in early infancy as well as the incidence of infectious diseases during youth are crucial for the development of an optimal immune defence and for the frequency of allergic diseases in future life.  The hygiene hypothesis as a reason for allergies gets more and more interesting as it was already confirmed by some facts. Children, that grew up on a farm and had contact with domestic pets, suffer less from allergies.  A poll held in Estonia showed that the bacteria flora of the gastrointestinal tract of children living there and which relatively often grow up on farms and spend a lot of time outdoors is much healthier than those of children from Sweden who scarcer grow up on farms.  Children from Germany are increasingly kept from germs. This is further supported by hypoallergenic baby food (allergy-free follow-on milk) and increased hygiene standards. Thus, the immune system has less contact with germs and produces significantly less antibodies, which are, however, needed for the defence of foreign substances. 
Breast milk - the best food against allergies
For a good immune system, breastfeeding the baby for at least 4 months is ideal. The antibodies of the mother are thereby transferred to the infant and the immune system gets strengthened. Until a few years ago, strict nutrition rules for pregnant and breastfeeding mothers were in place to lower the risk of allergies for your child. These women should, according to current research, either renounce on eggs, nuts, milk products or wheat products. It was also advised against gluten-containing baby food. Fish was also taboo as partly was even celery and carrots. Nowadays, especially these foods are highly popular for preventing allergies. If a fetus in the womb or a breastfed child already come in contact with various foodstuffs, the tolerance limit and the tolerance for these food ingredients even increases. This was discovered in long-term studies by the German Society for Allergology (DGAKI), the Medical Association of German Allergologists and the German Society of Pediatrics and Adolescent Medicine (DGKJ). 
Good to know: If babies with a food allergy are breastfed, the mothers have to avoid the specific food (allergen) whilst breastfeeding.
What is the role of the intestine?
Scientists assume that the increasing incidence of food allergies can be attributed to the changed composition and imbalance of the bacterial flora (gut flora). The intestinal microbiota comprises all intestinal bacteria that colonize our intestine already in early childhood. The human microbiome (totality of all microorganisms) plays an important role in the development and function of the immune system in the early life. As IgE-mediated food allergies are accompanied by a malfunction (dysregulation) of the immune system and a disturbed gut flora, there is a substantial interest in a possible correlation of the intestinal microbiota and food allergies. 
Risk factors for allergies
Generally, everyone can develop an allergy. So far, there are no set risk factors that encourage allergies. However, many studies indicate that the place of residence, the age, the gender, the family background and the presence of other allergies can be important factors in the development of an allergy. 
Further risk factors which are associated with food allergies are: 
- atopic dermatitis
- vitamin D deficiency
Non-genetic influences that increase the likelihood of a food allergy are: 
high age of the mother
How to prevent allergies
There are still no general recommendations on how to prevent a food allergy and no genes could clearly be related to the disease. In the current guidelines, criteria for preventive measures are mentioned. These recommendations are, however, in some aspects only valid exclusively for risk families. The latter are characterized by already one single incidence of an allergic disease within the family. However, some recommendations can also be taken into account by people not belonging to a risk group. The following suggestions should be taken into account for prevention of an allergy: 
- breastfeeding period of up to four months
- food poor in allergens is not advisable
- consumption of fish by the mother can have a protective effect
- avoid obesity of mother and child
- avoid having a cat as a pet (only for children at risk)
- avoid tobacco smoke from the pregnancy onwards
- prefer natural birth to Caesarean section
- avoid contact with mould growth
- minimize exposition to emissions from motor vehicles
Did you know that…
According to a comprehensive report undertaken in 2014 and published in the Clinical Reviews in Allergy and Immunology, the incidence of food allergies during infancy increases and can affect up to 15-20 % of babies. 
By avoiding the allergen approx. 2-3 years, a certain tolerance against the allergy-causing substance can develop. The specific antibodies can, however, still be determined by blood testing. The skin-prick test is mostly also positive.
Can allergies be reversed?
In case of a nut or fish allergy this effect is very rare. Cow’s milk allergy is cured in 90 % of cases. For example, children with cow’s milk allergy do no longer suffer from it in adulthood. This is possible as the corresponding organ, e.g. the gastrointestinal tract, can change with increasing age. Also the allergen can change from cow’s milk to grass pollen so that no longer an allergy cow’s milk but an allergy to grass pollen exists. 
Who is affected by allergies?
What are the different types of allergies?
In theory, you can develop an allergy against any kind of food if it contains a protein molecule. Often, unfortunately, against several foods. Related foodstuffs mostly contain the same allergens. This means that different foods can lead to allergic reactions.
One example: You have an allergy to fish protein. Thus, the reaction can not only occur to one fish species, but also to other or all fish species. 
Did you know that in a mixed diet which contains colouring agents, emulsifiers and spices, about 120 allergenic substances can be found?
What are the most common food allergies?
170 foods and food components were identified as allergens, of which only a small part is responsible for most of the food reactions. Many foodstuffs can cause an allergic reaction. The most common ones are:  
- cow’s milk
- tree nuts
Cow’s milk allergy
Cow’s milk allergy is the most common food allergy. Children are more often affected than adults.  The cow’s milk allergy normally develops during childhood and has completely developed until school age. A cow’s milk allergy comprises all types of milk products. In case of a cow’s milk allergy, in 92 % of cases also an goat’s milk allergy exists . This means that cow’s milk as well as goat’s milk and sheep’s milk should best be avoided. 
Please note: cow’s milk allergy should not be confused with lactose intolerance. Here you can find more information on lactose intolerance.
Hen’s egg allergy
Hen’s egg allergy is, apart from cow’s milk allergy, the second leading food allergy in childhood. The allergy can “grow out” and gets rare becoming an adult. With this allergy, the body reacts to some protein components which are mostly part of the egg white. This means that most people are only allergic to one part of the egg and not to the whole egg. 
Good to know: The cooking and processing of foods at high temperatures could either increase or decrease the allergenicity (allergenic potential) of foods depending on the type of food. The dry roasting of peanuts, for example, can increase their allergenicity. On the contrary, the cooking of eggs and milk changes the proteins’ structure which can reduce their allergenicity.  Most patients with an egg and milk allergy tolerate these foods in baked form. According to a study, 75 % of children allergic to milk tolerated products with heated milk.  As per another study carried out in Australia, 80 % of people allergic to egg tolerated baked egg. 
Nut-allergie: Peanut allergy
The peanut allergy can develop in adulthood or during childhood and it is highly likely that it persists for a lifetime.  According to a study, the nut allergy diagnosed during the first year of life of a child disappeared only in 22 % of cases during the next 4 years.  A peanut allergy is particularly worrisome as it leads more often than other food allergies to an allergic shock with the risk of a fatal allergic reaction. [26, 27]
In the study evaluating the deaths caused by food allergies, in 31 % of cases the death could be traced back to nuts. [26, 27] Another point is the high potential for tree nut associated cross-allergies. The cross-reaction was stated being 37 %. However, in spite of the potentially deadly and frequent reactions to tree nuts, no comprehensive studies have been carried out so far. 
Fish and crustacean allergy
A fish allergy normally develops during adulthood and is normally concerning all fish species. Thus, all fish should be avoided unless an oral test confirms that the allergy is limited to certain fish species only. Most fish allergy sufferers can tolerate crustaceans and vice versa.
A crustacean allergy usually develops during adulthood. Crustaceans comprise all crustacea including crab and lobster; molluscs (snails) including oysters, scallops and squids; and insects such as cockroaches, grasshoppers and dust mites. 
! Considering the severity of the shellfish allergy reaction and the related reaction to other crustacea, all crustaceans should be avoided. 
A wheat allergy most often develops during childhood and has normally disappeared before adulthood.  It must not be confused with celiac disease and wheat sensitivity. In case of a wheat allergy, an allergic reaction to the allergenic wheat protein exists and wheat must not - like in case of celiac disease - be avoided completely. The cross reactivity between the different grain types is 20 %.  Complete avoidance of all cereals in case of a wheat allergy can be harmful from a nutritional point of view and is thus not recommended.  In case of doubts concerning the allergy to other grain types, an oral provocation can be carried out.
Other types of food allergies - spice allergy
Spices belong to the most often used products in processed food, cosmetics and dental care products. The problem is, that in most cases these are not labelled which makes it most difficult to avoid spices. Apart from this, such an allergy is very often not diagnosed by the physician as there are no reliable skin and blood tests. A spice allergy seems not to occur frequently as only 2 % are affected worldwide.
! But attention: Due to the constantly increasing use of spices in foods, processed foods and a variety of cosmetics, experts assume that, over time, more and more people could develop a spice allergy. Which means, in turn, that the persons concerned would have to enormously restrict themselves. Also persons with birch pollen and mugwort pollen allergy are prone to spice allergies.
Common spice allergies are cinnamon and garlic, but a wide range of spices - from black pepper to vanilla - can cause allergies. Some spice mixes contain up to 18 different spices and it seems that the hotter a spice, the higher the chance to develop an allergy. 
Food allergy test
The clinical symptoms of a food allergy can vary considerably. They range from skin appearances, gastrointestinal complaints, respiratory symptoms to circulatory disorders.  Depending on the body organ that takes up the allergen, many different symptoms and combined symptoms can occur.  For this reason, it is recommended to conduct an in-depth anamnesis. Thereby, the results of further health checks can be supported. Moreover, the allergy triggers can be determined and whether these are IgE-mediated.
In total, there are four key tests for determining an allergy: 
- skin prick testing (SPT)
- specific IgE test
- elimination diet
- oral provocation test
How to test for food allergies?
If you suspect food allergies or intolerances, there are different options. Which diagnostic method is the best depends, amongst others, on your age, on your medical history and the test possibilities.
Skin Prick Testing (SPT)
This test allows you to get a result within 20 minutes. Your skin is pricked with a tiny amount of the suspected allergen to see if there's a reaction. If there is, the skin around the prick will very quickly become itchy and a red, swollen mark called a wheal will appear. There is also a control prick with a liquid not containing an allergen so you can compare the results.
- Advantage: painless, quick result, possibly causes strong itching
The SPT is an indirect evidence for the existence of allergen specific IgE antibodies on the mast cells in the skin. 
The specific IgE Test
The specific IgE test is a blood test which determines the number of IgE antibodies against the tested foods. If the result is positive, the allergy can be diagnosed by means of an also positive anamnesis. 
If antibodies are determined but no symptoms occur?
If there is a positive IgE result but you don’t feel symptoms, this may be a sign that you body build up a self-defence (immune tolerance). In this case, you should not completely eliminate this food from your diet, as this might lead to stronger symptoms when eating this food again. Try to reduce the consumption of this food. It is recommended to eat it only once every four days to relieve your intestine. A cross-reaction with inhalation allergens very often is the real cause for the measured positive reaction.
The specific IgE test is an indication of allergen specific IgE antibodies in blood (serum).
! Attention: The interpretation of the skin prick test and of the specific IgE blood test only makes sense only in connection with the clinical health case history as a sensitization does not necessarily cause allergy symptoms.
If there are no clear results, for example due to an unclear anamnesis, no elimination diet or provocation test is performed. 
IgE conclusion - what do I have to do?
- Avoid the foods that tested positive AND that cause symptoms
- Eat foods which tested positive AND do NOT cause symptoms only once every four days
- Disadvantage: blood sample taking may be painful
- Advantage: quick and comprehensive food allergy check
The elimination diet
An elimination diet means that you eliminate the foods suspected to cause the food allergy from your diet. In case of an IgE-mediated allergy, this diet should not be followed longer than two to four weeks. Within this period, first results should be noticeable. Hereby, unnecessary food restrictions can be avoided. 
- Disadvantage: takes a long time and is laborious, “diet mistakes” possible
- Advantage: patients are actively involved, results are quickly noticeable
Oral provocation test
The oral provocation test is done in order to finally confirm the food allergy diagnosis or to prove the oral tolerance of a certain foodstuff. The food which is expected to cause a possible reaction within a certain time is administered to the patient on-site. Only if symptoms fail to occur, a clear conclusion is possible: there is no allergy. The provocation is cancelled as soon as clinical symptoms are noticeable or if symptoms fail to occur by the end of the testing period. This method bears the risk of an allergic shock. Therefore, this test should only be done under medical supervision.
- Advantage: high significance
- Disadvantage: time-consuming and resource-intensive
What treatment options are there?
There are two different types of treatment: acute treatment and long-term therapy. The acute therapy is the short-term treatment of acute and serious allergy reactions. Long-term therapy is aimed at eliminating the risk of future allergy reactions. Acute immune reactions can only be treated with medication. For example, an allergic shock is treated with drugs such as adrenaline, antihistamines, bronchodilators and glucocorticosteroids.
Effect of antihistamines
Did you know that there is only little evidence for the positive effect of antihistamines during anaphylactic shock?
Course of treatment
Currently, there are no known treatments for a prevention or therapy of a food allergy. The management of food allergies consists of avoiding the causative foods and of knowing what to do in case the causative food is eaten accidentally.
For the treatment of a food allergy, a specialized physician or nutritionist should always be consulted. The usual treatment is, at first, an elimination diet in case of a suspected allergy. This means that the causative food is avoided during the diet.
Afterwards, a “food challenge” is carried out by eating the suspected food again. This step should be monitored by a physician as symptoms up to an allergic shock can occur. The provocation is monitored for 24 hours. In case the result is positive, i.e. the food is responsible for the allergic reaction, a specific long-term elimination diet must be followed.
In the negative case, no specific diet is required. The result is negative if no symptoms occur.
In case of a suspected delayed type food allergy (IgG reaction), the patient is monitored 48 instead of 24 hours. This test can have a positive or negative outcome without symptoms as well and has the same consequences as an immediate type reaction - a specific long-term elimination diet or no specific dietary requirements in case there are no symptoms. 
How do I test for food allergies?
Apart from family physicians, allergists and alternative practitioners, you can test possible allergies and intolerances here. The Food Reaction Test contains an analysis of 57 groups of foods which cover 95 % of generic triggers for allergies and intolerances in Europe.
Chicken, egg white
Beef, pork, lamb
Cereals containing gluten
Carrot, celery, tomato
Peach, kiwi, strawberry, orange, apple
Nutritional management for food allergy
The first thing in nutrition therapy is avoidance of the diagnosed allergens (elimination diet). After this phase of strict elimination, the diet is changed so that the allergen is included again in the diet in small quantities and under medical supervision. In children, the allergy often disappears by means of this diet within one to two years.
In case you require assistance for the dietary change, we would be pleased to assist you. Our nutritionists discuss the result with you and give you tips and recommendations on how to apply them in daily life.
Allergy and sports
Sports activities promote allergies. This allergy promotion leads to a lowering of the reaction threshold or an increase of symptoms.
The reaction threshold is the level at which the allergen causes an allergic reaction. This means that for example instead of consumption of a complete meal now only traces of the causative food can already cause an allergic reaction.
The so-called exercise-induced anaphylaxis is defined as an allergic reaction during or immediately after physical activity. When training, the body temperature increases. In case you consume an allergen before doing sports, symptoms such as urticaria or itching can occur or you may feel dizzy. The best way to avoid exercise-induced food allergies is avoidance of the causative food at least 4 to 5 hours prior to any exercise. 
Stress and allergy
In a study published in the journal “Annals of Allergy, Asthma and Immunology” scientists of the Ohio State University, USA, discussed the correlation between stress and allergies. 
“Allergies are not caused by stress. Annoying symptoms, however, can make your daily life even more stressful. It seems, however, that stress deteriorates symptoms such as sneezing, skin rashes and others.”
In order to verify this hypothesis, scientists of the university of Ohio monitored 179 study participants for 12 weeks. Within this time span, in 39 % of the participants allergy symptoms occurred. The researchers also discovered: The group with the allergy symptoms had higher stress levels than the group in which allergy symptoms occurred only once or twice. Moreover, many participants of the “symptom group” stated to be often in bad mood. 
Conclusion: The study results suggest that allergy sufferers should not only pay attention to avoiding the allergy inducers but also to regular relaxation. Allergy sufferers seem to have an increased susceptibility to stress. Deep breathing, yoga, meditation and learning stress coping strategies can be helpful.
! Attention: Smoking is no relaxation technique and can worsen symptoms.
Everyone knows that excessive alcohol consumption has significant negative effects. Also with regard to allergies, alcohol plays a major role. Alcoholics have higher IgE antibody values than non-alcoholics. Most frequently, alcoholics react to ingredients which are frequently present in alcoholic beverages such as sulphites.  Sulphites are often used as preservative agent in wine, but also in dried fruit and potato products.
Conclusion: Alcohol can enhance allergic reactions through the following mechanisms: Alcoholics have higher IgE antibody levels than non-alcoholics; one can react to components of alcoholic beverages (e.g. sulphites) and alcohol can be an aggravating factor.
Allergies and infections
Studies have shown that allergies can be enhanced by infections. The background for this is that feverish illnesses, in particular, increase circulation and this causes an influx of allergens. Especially in the gastrointestinal tract, there is another aggravating factor: larger quantities of undigested proteins pass through the mucous membrane. Thereby, these proteins come in contact with the sensitive immune system and more easily cause allergic reactions. 
Skin conditions associated with allergies
Atopic dermatitis, also known as neurodermatitis, is probably the most common skin disease accompanied by an allergy. Neurodermatitis appears in patches on the neck, scalp, shoulders, feet, ankles, wrists and hands. The affected patch of skin becomes thick, leathery and even itchier the more it is rubbed or scratched as a result of irritated nerve endings in the skin. Mostly such skin disorders occur for the first time during childhood. For decades, numerous triggers of atopic dermatitis were determined. These include airborne allergens such as grass pollen, food allergies and bacterial infections. 
80 % of allergies are associated with inflammatory skin diseases.
Particularly often food allergies occur in combination with atopic dermatitis. In this case, cow’s milk and chicken egg are among the provocateurs of skin inflammations.
Ellman and his colleagues discovered in 2002 that egg, milk, wheat, soya, nuts and seafood are the main triggers (90 %) for atopic dermatitis in children and young adults. 
According to studies, the atopic dermatitis can be alleviated by 50 % by using e.g. foods based on rice milk instead of allergenic cow’s milk. 
Conclusion: In summary it can be said that it is important to find out the cause of skin disorders such as, for example, atopic dermatitis. Food allergies can nowadays easily be determined by blood or skin tests. In case of known allergies, wellbeing can be restored and the main problem thus reduced by replacing the causative food.
Food intolerance or food allergy? Is there a difference? Yes, definitely!
In common parlance, the term “food intolerance” is used synonymously for “food allergy”. However, you now know that a food allergy is the response of the body’s immune system as food components, above all proteins, are by mistake recognized as foreign to the body. A food intolerance, on the other hand, distinguishes by its immunological defence reaction.
What is a food intolerance?
A food intolerance is a reaction of the immune system to certain foodstuffs to which the body reacts sensitively. Unlike in the case of a food allergy, the body does not produce IgE antibodies against the food allergens. Instead, IgG4 antibodies are participating in the immune reaction. Thus, food intolerances and food allergies can be distinguished by their diagnostic parameters. Moreover, in case of a food intolerance, symptoms can be felt only several hours after the meal. The precise causes of intolerances are difficult to analyze as these vary considerably from person to person.
Almost 15-20 % of the world population are affected by food intolerances. 
Facts and figures relating to food intolerances
- Intolerances to foodstuffs are more often reported or suspected than food allergies. According to a survey carried out in Great Britain, 20 % of households assumed to suffer from food intolerance. However, it could be shown that this was true only for 2 % out of these 20 %. 
- Studies have also proved that women are more often affected by food intolerances than men. 
- The number of people affected by food allergy is said to rise each year. 
- According to research, genetic factors and environmental influences are taken into consideration as possible causes. Even the education of the parents should play a role.  They can correspond to the allergy triggers.
- In case of an aversion to certain foodstuffs, symptoms of a food intolerance can develop. For example, if you receive bad news during the meal. Thereupon, the body reacts with intolerance symptoms each time the respective foodstuff is eaten again. 
Different types of food intolerances
The term “food intolerance” either denotes a non-IgE response of the immune system to certain proteins, carbohydrates and other chemical substances or a non-IgE mediated reaction.  In the latter case, instead of the intervention of the immune system, transport mechanisms in the gastrointestinal tract are faulty or non-existent due to impaired or too low enzyme activity. 
In case of food intolerance, the body is not able to fully or at least partially break down and metabolize certain foodstuffs.
The inadequate digestion causes disorders and the response generally takes place over a prolonged period of time.
Whereas an IgG4-mediated food reaction focusses - like the IgE antibodies - on the proteins of a foodstuff (= the antigens), food intolerances can also be caused by other chemical components. For example, food intolerances can exist to caffeine, to the biogenic amine tyramine in cheese or to the flavour enhancer glutamate.
Good to know:
Biogenic amines are formed from amino acids and have hormone-like effects. The best-known biogenic amine is histamine.
Besides, all offenders such as artificial sweeteners, preserving agents and food colourings can cause similar reactions if consumed excessively. These intolerances are also based on non-immunological processes and are similar to pseudoallergies.
What are symptoms of food intolerance?
In case your body does not tolerate a certain foodstuff, symptoms vary greatly. 
Many consecutive reactions can be mistaken for the symptoms of a food allergy or of an infection. The main symptoms of food intolerance are:
- gastrointestinal problems like nausea, constipation, vomiting, flatulence
- headache and migraine
- wheezing and running nose
- skin rashes
Many people are especially troubled by flatulence which is found very unpleasant. This shame can dominate people’s lifes that much that they are afraid of engaging with public and could eventually cut themselves off. For this reason, you should search for help if you often feel the above-mentioned symptoms in order to reveal the causes of your physical complaints and to maintain your quality of life.
As you can see, these are very common symptoms which can be felt in case of food intolerance. However, these are also typical for infections such as e.g. a cold. Therefore, it is difficult to diagnose a food intolerance only based on the symptoms. A blood test is required to really determine the cause.
Types of food intolerance / malabsorption
Due to malfunction, partial or complete lack of certain enzymes, the body cannot digest certain food components and thus cannot metabolize them. This category includes in particular substances such as fructose, sorbitol, lactose, gluten and histamine.
Fructose malabsorption vs (hereditary) fructose intolerance
Nearly one in every three persons in Germany suffers from malabsorption of fruit sugar, also called fructose.  Fructose is part of fruits and gives them their sweetness. This sugar is transported from the intestine to the blood by means of a transport protein. If this transport protein is impaired in its function, fructose cannot be metabolized.
Attention: Fructose malabsorption may not be confused with the much more severe (hereditary) fructose intolerance!
Sorbitol is a sugar substitute and is used as a nutritive sweetener. Sorbitol interferes with fructose absorption and can thus not be metabolized as it is converted to fructose. 
Lactose intolerance (milk sugar intolerance)
An intolerance to milk sugar is not rare anymore. 15 % of Germans are affected by the so-called lactose intolerance and only tolerate small quantities of milk sugar. This is caused by the lack of enzyme lactase in the small intestines which splits lactose so that the body can use it. If the body produces too little lactase or if lactase cannot work properly, less lactose can be broken down.
Gluten related disorders
Gluten related disorders is the umbrella term for all diseases triggered by gluten. Gluten-related disorders include (hereditary) celiac disease and non-celiac gluten sensitivity. "Gluten intolerance" and "gluten sensitivity" are sometimes used as synonyms for gluten-related disorders. In both cases, gluten cannot be tolerated and causes an immune-mediated inflammation of the intestinal mucosa.
An intolerance to histamine is very rare. Histamine is an endogenous messenger substance and can also be found in foods. Some people can only partly or not at all break down the histamine contained in food. In this context, the enzyme diamine oxidase (= DAO) plays a key role.
Food intolerance diagnosis
In general, it is necessary to do a blood test to reliably diagnose food intolerances. No matter, whether it is a food allergy, intolerance or malabsorption. All three types differ by typical blood values which are used for diagnostics.
The Cerascreen® Food Reaction Test provides evidence whether you are suffering from an allergy or an intolerance to certain foods. The test contains an analysis of 57 groups of foods which cover 95% of generic triggers for allergies and intolerances in Europe. A few drops of blood from your finger tip are sufficient for the analysis. The test kit contains several pages of illustrated instructions, explaining step by step how a blood sample is taken and how the test is performed. A comprehensive IgE and IgG4 screening of your blood is then performed in our human diagnostic laboratory.
Please note that for the analysis of the above-mentioned intolerances and malabsorptions - apart from histamine intolerance - your exhaled breath has to be analysed.
In case of a suspected food allergy, IgE antibodies have to be measured, whereas IgG4 antibodies are determined in case of suspected food intolerances. An IgG4-mediated food reaction shows serologically negative IgE values. 
What does IgG4 antibody mean?
An IgG4 antibody is a type of antibody belonging to the immunoglobulin subclass G (IgG). As soon as a food, that you don’t tolerate, has been consumed, an increased production of IgG4 antibodies takes place. Those bind to the proteins of the food. In case of a strong reaction, increased IgG4 values in your blood can be measured. In order to fight foreign substances, defense and inflammatory reactions take place. However, these are not as strong as in case of a food allergy. For this reason, they are occuring only after a certain period of time.
It is supposed that IgG4-mediated food reactions are caused by an increased permeability of the intestinal mucosa. Food components can thus easily penetrate the mucous membrane and get into the blood, which triggers IgG4 production and starts the intolerance reaction. 
It is important that the food has been eaten during the week prior to sample taking for testing purposes, as otherwise antibodies could not be found in the blood!
Summary Cerascreen® Food Reaction Test:
- Comprehensive IgE and IgG4 screening of your blood to provide evidence when you suspect food allergies or food intolerances.
- Pain-free and easy to perform at home sample taking.
- A few drops of blood from your finger tip are sufficient for the analysis.
- You receive a comprehensive result report along with personal advice and individual nutritional and dietary supplement recommendations.
- The test can, however, not be used to diagnose a lactose, gluten or histamine intolerance, a fructose or sorbitol malabsorption or celiac disease.
How do I test for food intolerances?
Apart from family physicians, allergists and alternative practitioners, you can test possible allergies and intolerances here. The Food Reaction Test contains an analysis of 57 food groups which cover 95 % of generic triggers for allergies and intolerances in Europe. Order the Food Reaction test and send a small blood sample to our certified laboratory. The test provides evidence whether you have an allergy or intolerance to up to 57 possible foods. On top, you receive a comprehensive result report along with personal advice and individual nutritional as well as dietary supplement recommendations.
The Cerascreen® Food Reaction Test analyses your blood for the following IgG4 antibodies:
Chicken, turkey, eggs
Pollack, salmon, tuna, cod
Cow’s milk, sheep’s milk, goat’s milk, casein
Cereals containing gluten
Amaranth, quinoa, maize, rice
Hazelnut, almond, walnut
Pineapple, banana, kiwi
How to uncover a food intolerance
Unfortunately, it is difficult to diagnose a food intolerance without a blood test. Especially its wide variety of symptoms which could also belong to other general diseases, complicates diagnosis. The symptoms could also stand for an infection or diseases such as irritable bowel syndrome, anxiety disorders and chronic inflammatory bowel diseases such as Crohn’s disease or ulcerating colitis.
Most common symptoms are stomach pain, flatulence, diarrhoea and skin rashes which could occur some hours after consumption of the foodstuffs.
By means of a nutrition diary you can roughly estimate the intolerance, especially if symptoms last longer and occur more often.
Remember: A blood test at home or at the doctor provides a much more reliable result than “self diagnosis”!
According to a survey carried out in Great Britain, 20 % of households assumed to suffer from food intolerance. However, a study could evidence that this was true for 2 % out of these 20 % only.
In case you opt for a nutrition diary, which you should also present to your physician, nutritionist or alternative practitioner, please pay attention to diligence and frankness.
- Always note down the exact mealtime after eating.
- Note down each individual foodstuff and beverage consumed - also in case a lot of fast-food or sweets are part of your diet. Frankness pays off!
- Always note down your health complaints that occur after consumption. In case of a food intolerance, symptoms normally can be felt a few hours after mealtime. Each belly rumbling must be noted down. This facilitates the diagnosis of a food allergy.
For nutrition diaries, the following rule applies: “Quantity and quality!”
Better note down each detail than concealing something. Health management requires honesty.
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