Food allergy is a developing concern, and detection of symptoms, observation of typical food allergens, and management of reactions are important for patients and professionals. Food allergy has two types the first type is defined by immediate reaction (IgE-mediated food allergies) means that IgE allergy antibodies are a reason of the allergic reaction to a food The second type of food allergic reaction is a late reaction (Non IgE mediated food allergies) means that caused by a reaction involving other components of the immune system apart from IgE antibodies. This reaction can generate many symptoms therefore there are some diagnoses that help to determine the symptoms and causes of food allergy which is different in children and in adult. While there is no medical cure for food allergy there are some specific treatments to reduce or to ruin the food allergy including (antihistamine and epinephrine).

Keywords: food allergy, causes, symptoms, diagnosis, treatment

Introduction
A food allergy happens when the body’s immune system detects food as destructive and reacts by causing symptoms, this is an allergic reaction and foods that cause allergic reactions are allergens.
While most allergic reactions are mild and easily handled, also the responses can also be serious and life threatening, causing anaphylaxis and even death.
A food allergy is an abnormal immune response that generally happens after food enters the body and binds to specific receptors (IgE-mediated). Symptoms usually occur within hours of ingestion, and can affect the cutaneous, gastrointestinal, cardiac and/or respiratory systems. Current management includes avoidance of the offending food and emergency medications as needed.). Many sorts of adverse food reactions are frequently confused with food allergies. Allergists consider food allergy reaction as an abnormal response of the immune system to food protein. These ordinary responses are mediated by immunoglobulin E antibodies (IgE-mediated) or through immune cells (non-IgE-mediated).
This report will concentrate the types of foods that cause allergic reaction the types of diagnosis and how will be treated.

Types
Generally, there are two kinds of food allergy.
The first type is defined by immediate reaction, which is recognized by identifying signs in a few minutes, or even seconds after ingestion of the food, which is anaphylaxis (shock), urticaria, angioneurotic edema (skin swelling). Eggs, nuts, peanuts, fish and shellfish are generally foods that frequently cause this type of allergy. IgE mediated means the IgE allergy antibodies are a cause of the allergic reaction. This type of response is the most frequent type of food allergic reaction with signs and symptoms together with hives, redness of the skin, vomiting and in greater extreme cases anaphylaxis.
Symptoms of IgE mediated food allergy generally happen suddenly, after eating the food that cause the reaction. A reaction can show up after eating only a small amount of the food and can be life threatening.

The second type of food allergic reaction is a late reaction, in which the signs(fatigue, irritability, depression, hyperactivity, insomnia, headache, poor concentration, paleness, itching limbs, involuntary bedwetting, asthma, colds, indigestion, colic, diarrhea, bloating and pores and skin lesions) show up a few hours, and even a few days after foods ingested. Foods that motive this type of reaction are milk, chocolate, legumes, citrus and food additives. Because of this delay, it is challenging to determine what the cause of food allergies is.
Non IgE mediated food allergies are brought on through other parts of the immune system but the precise mechanism is now not well understood. This kind of hypersensitive reaction typically impacts the bowel and the skin. Symptoms develop hours after consuming the food and can be dose-dependent, also this type is not often life threatening however can lead abnormal growth and development in younger children.

Causes
In the case of allergic reactions to food, the immune system identifies the proteins contained within food as foreign bodies and mounts an attack in the same way as it does when microbes and bacteria are detected. The immune system releases several chemical mediators such as histamine that lead to symptoms of the allergy. Most commonly, food allergies are triggered by the immunoglobulin E (IgE) antibody.
According to the Food and Drugs Administration (FDA) the eight most common food types to cause allergies are:
• Eggs.
• Milk.
• Peanuts.
• Tree nuts.
• Fish.
• Shellfish.
• Wheat.
• Soy.
Approximately 4-6% of children and 1-3 of adults are diagnosed with food allergy.In children, the foods that most commonly cause an allergic reaction are:
• eggs
• milk – if a child has an allergy to cow’s milk, they’re probably allergic to all types of milk
• soya
• wheat
• peanuts
In adults, the foods that most commonly cause an allergic reaction are:
• peanuts
• tree nuts – such as walnuts, brazil nuts, almonds and pistachios
• fish
• shellfish – such as crab, lobster and prawns
However, any type of food can potentially cause an allergy. Allergic reactions have been reported in association with:
• celery or celeriac – this can sometimes cause anaphylactic shock
• gluten – a type of protein found in cereals
• mustard
• sesame seeds
• fruit and vegetables – these usually only cause symptoms affecting the mouth, lips and throat (oral allergy syndrome)
• pine nuts (a type of seed)
• meat – some people are allergic to just one type of meat, while others are allergic to a range of meats; a common symptom is skin irritation

Symptoms
The immune system of the body keeps the body safe and healthy from many risks by fighting with infection. A food allergy reaction response happen when your immune system overreacts to a food or a substance in a food, figuring out it as a risk and triggering a protective response. Food allergy can take place a huge range of symptoms. Symptoms of a food allergy reaction can vary from moderate to severe. In fact an early response can induce many problems does not mean all the responses are similar, a food that can induce only moderate signs in some time can also induce the severe signs and symptoms at some other time.
Most food-related signs occur within two hours of ingestion; regularly they start within minutes. In some very rare cases, the response can also be delayed through four to six hours or even longer. Delayed reactions are most normally seen in children who strengthen eczema as a symptom of food allergy and in people with an uncommon allergic reaction to red meat induced by the bite of a lone star tick
Not absolutely everyone who experiences symptoms after eating certain foods has a food allergy or need to keep away from that food entirely; for instance, some humans ride an itchy mouth and throat after eating a raw or uncooked fruit or vegetable. This may indicate oral allergy syndrome – a reaction to pollen, not to the food itself. The immune system acknowledges the pollen and comparable proteins in the food and directs an allergic response to it.
The appearance of itching of the lips or tongue, repeated vomiting, frequent diarrhea or urticaria can also be described as the most frequent symptoms, which reveal an allergic response to food.
Symptoms of an allergic response may also involve the skin, the gastrointestinal tract, the cardiovascular system and the respiratory tract. They can surface in one or more of the following ways:
? Vomiting and/or stomach cramps
? Hives
? Shortness of breath
? Wheezing
? Repetitive cough
? Shock or circulatory collapse
? Tight, hoarse throat; trouble swallowing
? Swelling of the tongue, affecting the potential to talk or breathe
? Weak pulse
? Pale or blue coloring of skin
? Dizziness or feeling faint
? Anaphylaxis, a probably life-threatening response that can impair respiration and send the body into shock; reactions may additionally affect extraordinary parts of the body (for example, a stomachache accompanied by a rash)

Diagnosis
Diagnostic food allergy testing offers clues about the causes of symptoms, but it cannot determine whether someone has a food allergy with absolute certainty without a challenged study. Still, when a food allergy is suspected, it’s critically important to consult with an allergist who can determine which food allergy tests to perform, determine if food allergy exists, and counsel patients on food allergy management once the diagnosis has been established.
To make a diagnosis, allergists ask detailed questions about the history of allergy symptoms. The patient must be prepared to answer questions about the specific food and the portions they consumed, the length of time that it took for symptoms to develop, the symptoms themselves, and how long they lasted. The allergist will normally order a blood test (such as an ImmunoCAP test) and/or perform a skin prick food allergic reaction tests, which point out whether food-specific IgE antibodies are existing in your body.

There’s no perfect test used to confirm a food allergy. Your doctor will consider a number of factors before making a diagnosis. These factors include.
• Your symptoms. Give your doctor a detailed history of your symptoms — which foods, and how much, seem to cause problems.
• Your family history of allergies. Also share information about members of your family who have allergies of any kind.
• A physical examination. A careful exam can often identify or exclude other medical problems.
• A skin test. A skin prick test can determine your response to a specific food. In this test, a small quantity of the suspected food is placed on the skin of your forearm or back. A doctor or any other health professional then pricks your skin with a needle to permit tiny amount of the substance below your skin surface.
If you’re allergic to a precise substance being tested, you increase a raised bump or reaction. A high quality response to this test isn’t enough to affirm a food allergy.
• A blood test. A blood take a look at can measure your immune system’s response to specific ingredients by measuring the allergy-related antibody known as immunoglobulin E (IgE).
For this test, a blood sample taken in your doctor’s workplace is sent to a clinical laboratory, the place where different foods can be tested

• Elimination diet. You may be asked to eliminate suspect foods for a week or two and then add the food items back into your diet one at a time. This process can help link symptoms to specific foods. However, elimination diets aren’t foolproof.
An elimination diet can’t tell you whether your reaction to a food is a true allergy instead of food sensitivity. Also, if you’ve had a severe reaction to a food in the past, an elimination diet may not be safe.
• Oral food challenge. During this test, done in the doctor’s office, you’ll be given small but increasing amounts of the food suspected of causing your symptoms. If you don’t have a reaction during this test, you may be able to include this food in your diet again.

Your allergist will interpret these results and use them to aid in a diagnosis. A positive test result to a specific food does not always indicate that a patient will react to that food when it’s eaten. A negative test is more helpful to rule out a food allergy. Neither test, by its level of IgE antibodies or the size of the wheal, necessarily predicts the severity of a food allergic reaction.

Treatments
Since there is no medical cure for food allergy, the only option for allergic people is strict avoidance of the offending food, even in trace amounts. The most effective way of avoiding the offending food is to read the food labels carefully and to ask about ingredients. Therefore anyone involved in providing foods needs to know and inform the ingredients and possible cross-contaminants in the food sold to allergic people, as they must avoid the offending food even in trace amounts.
For a minor allergic reaction, over-the-counter or prescribed antihistamines may help reduce symptoms. These drugs can be taken after exposure to an allergy-causing food to help relieve itching or hives. However, antihistamines can’t treat a severe allergic reaction.
For a severe allergic reaction, you may additionally want an emergency injection of epinephrine and a trip to the emergency room. Many people with allergic reactions lift an epinephrine auto injector (Adrenaclick, EpiPen). This device is a mixed syringe and hid needle that injects a single dose of medicinal drug when pressed towards your thigh.
Discussion
Food allergy is abnormal responses to a food that related to the body’s immune system which is divided into two types the mediate reaction that occur in short period of time after taking the food and late reaction that happen in a long period time after the food ingested, there many foods the cause food allergy but according to the Food and Drugs Administration (FDA) the eight most common food that cause about %90 of food allergies are egg, milk, peanuts, tree nuts, fish, shellfish, wheat, soy. Individual with food allergy will develop symptoms from mild to severe; the range in children is more than in adult that diagnosed with food allergy. There is not any specific test for diagnosing the food allergy however there are some factors that the doctors ask for diagnosing, while there are many treatment for this abnormal response but the only way to manage the food allergy is to avoid the food or knowing the food that cause allergic reaction.

Conclusion
In conclusion, food allergy a group of disorder characterized by immunologic responses to specific food proteins. Most of food allergy is easily treated and some of them can be serious and life threatening, the food allergy contain two type the mediated reaction which means the igE the other type is late reaction which is non igE mediated food, there some foods can cause an adverse reaction, the person who has allergic with many foods may experience some symptoms from moderate to severe, most of food allergy is easily treated and some of them can be serious and life threatening. There is no perfect test used to diagnosis the food allergy however there are some factors the doctor will ask for before making a diagnosis include skin test, blood test and many others. There are some treatments for a minor allergic reaction and severe allergic reaction which contain (antihistamines) for minor and injection of epinephrine for severe reaction despite the this treatments there is a tip to avoid this reaction which is reading the food labels to know ingredients in order to know if this food has allergic reaction to you or not.

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