Every year, millions of people have allergic reactions to food. Is it true that people are born with food allergies or do they develop them throughout their life? Although food allergies are more prevalent in young children and people with family history, most of them usually develop early in life. A new study conducted at the University of Southampton showed the prevalence of two different types of food hypersensitivities and the risk factors associated with them.

There are many foods that cause food allergy. However, eight top foods known to cause most of allergic reactions are milk, eggs, peanuts, tree nuts, fish, shellfish, soy and wheat. In principle, all we need to do is avoid consumption of these allergic foods. A task like can be difficult and nearly impossible to achieve knowing the wide variety of meal menus that are primarily composed of these ingredients. They are not only ingredients found in meals we eat but they are also components of some medications. For example, influenza vaccines usually contain a small amount of egg protein. At first you might think that people allergic to eggs should avoid getting the flu vaccine. Actually, that is not always the case. According to the American Academy of Allergy, Asthma & Immunology (AAAAI), flu vaccines can be safely administered to egg allergic individuals, whether in the primary care provider’s office or allergist’s office depending on how severe their allergy to eggs is. There are also several flu vaccine options without any egg protein, including Flublok. Egg-allergic individuals should always consult their physician before getting the flu vaccine.

Another problem in our society is the misinterpretation of food allergies as food intolerance. Often, these two terms are used interchangeably when in fact they are two different conditions. Food allergies (also known as food hypersensitivity) occur when your body’s immune system reacts to a substance in a food, such as a protein. Your immunity does not recognize that substance and interprets it as dangerous. As a result, your immunity system sets off cascade pathway reactions within your body to fight that substance. Meanwhile, food intolerance occurs when your body is unable to digest a certain component of a food, such as lactose, a sugar found in milk.

The symptoms of food allergies are different from symptoms of food intolerance. Symptoms caused by food allergies can be mild, severe and even life-threatening. They also occur immediately after consumption of the problematic food. On the other hand, symptoms of food intolerance usually take longer to become noticeable. The most common ones are stomach ache, cough, bloating, headaches and they are not life threatening. For example, milk allergy is a reaction of our body’s immune system to one or more milk proteins and can be life threatening when just a small amount of milk or milk product is consumed. People with lactose intolerance may feel uncomfortable after consuming milk and milk products, but it is usually not life-threatening. 

If someone suspects to be allergic to a food or if parents suspect their child might have food hypersensitivity they should do a laboratory blood test for immunoglobulin E (IgE). IgE test measures the blood level of immunoglobulin E, one of the five subclasses of antibodies. It is made by our immune system to attack harmful antigens, in this case allergens. These tests are only useful for IgE mediated food reactions and therefore are not useful in diagnosing non IgE mediated food allergies. IgE mediated and non-IgE mediated should be considered as two separate conditions. Our body reacts differently to them, and the risk factors associated with them are also distinct from each other. Therefore, it is important that health care professionals recognize that a child may be reacting to a food despite test results being negative, explained Dr. Kate Grimshaw, senior research fellow at the University of Southampton and specialist pediatric dietitian at Southampton Children’s Hospital.

The study conducted at the University of Southampton, examined 1140 pregnant women during their pregnancy and after childbirth, until the babies were two years old. The reactions are split into two groups IgE-mediated and non-IgE mediated. IgE-mediated reactions cause a range of immediate symptoms such as skin rashes, vomiting, and respiratory issues. In some cases, they can also cause life-threatening reactions. On the other hand, non-IgE mediated reactions occur around 4 to 28 hours after ingesting an incident food and may cause stomach complaints such as diarrhea or constipation among other problems, none of which are life threatening reactions.

The researchers also found that these two different types of food hypersensitivities are associated with different risk factors. Over half of the children who reacted to milk did not have an IgE mediated allergy, whereas for the vast majority of children who reacted to egg and peanut, their reaction was IgE mediated. Risk factors differed between IgE mediated and non-IgE mediated reactions. Egg and peanut allergies, most often occurring as IgE-mediated food allergy, are worse when in conjunction with eczema or rhinitis. Meanwhile, non-IgE mediated food allergy increased risk was associated with having a pet in the house and the age at which solid food was introduced to an infant.

The researchers concluded that a healthy diet was found to be protective for both types of reactions. This is likely due to the disease-preventing and immune-boosting characteristics of the nutrients in fruits and vegetables.

Factors such as eczema and rhinitis are associated with food allergy. Pet ownership may increase the likelihood of gut reactions to food, perhaps by altering the gut flora, which can affect how the digestive system works. Possibly due to a certain gene defect that prevents the skin barrier from forming correctly, leading to possible exposure of the immune system to allergens, explained Dr. Kate Grimshaw.

This study is a new insight into the possible risk factors associated with food allergies and remedies which will help other researchers like Professor Graham Roberts and his team from the University of Southampton, who plan to reassess all participants of this study, to discover what happens to allergies that started in early childhood and find out which of those babies when at older age will develop allergies and asthma.

 

COPYRIGHT: This article is property of We Speak Science, a nonprofit institution co-founded by Dr. Detina Zalli (Harvard University) and Dr. Argita Zalli (Imperial College London). The article is written by Dr. Detina Zalli and MSc. Gjena Dura (Molecular Biologist, University of Tirana).

 

References:

http://www.aaaai.org/Aaaai/media/MediaLibrary/PDF%20Documents/Libraries/EL-food-allergies-vs-intolerance-patient.pdf

http://www.southampton.ac.uk/news/2016/03/allergy-grimshaw.page

https://www.sciencedaily.com/releases/2016/02/160229082249.htm

http://www.ncbi.nlm.nih.gov/pubmed/14657884

http://www.niaid.nih.gov/topics/foodAllergy/clinical/Documents/FAGuidelinesExecSummary.pdf

http://www.webmd.com › Allergies › Guide

http://www.mayoclinic.org/diseases-conditions/food-allergy/basics/definition/con-20019293

https://search.cdc.gov/search?query=Egg+Allergy+and+the+Flu+Vaccine&utf8=%E2%9C%93&affiliate=cdc-main

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