Prevalence and diagnostics of food allergy and therapeutic considerations

By Anamika Chaudhary on March 14, 2017

Food allergy is an allergic reaction which is instigated with consumption of food which contains certain proteins, which can overreact with the immune system. Some of the major signs and symptoms of food allergy are:

  • red or itchy skin,
  • swelling,
  • teary eyes,
  • throat tightness,
  • trouble breathing (food allergies: reducing the risks, 2009).

Common risk factors associated with this allergy is when the person has family history or asthma. As compared to adults, food allergy is more prevalent among children. This is because children have an immature digestive system. In addition, increase in the intestinal microbial activity and lack of awareness about the disease among parents are major reasons (Sicherer, Scott H. & Sampson, 2014).

Prevalence of food allergy

Globally 200-500 million people suffer from food allergy and it mainly affects the quality of life mainly children (5-8%). In adults, the prevalence is considerable low (1-2%) and no country has reported a decline in food allergy in the last decade (Pawankar, 2013). Among the case countries, most of the countries report a prevalence of less than 10%.

In the case of the United States, statistics reflect that 8.96% of people are suffering from food allergy (Sicherer et al, 2014). According to FDA (2016), the common food products, from which the population is allergic include; milk, eggs, fish, peanuts, wheat, soybeans, and tree nuts like almond, pecans and walnuts. Consequently, prevalence percentage of 8.5% was observed among the population in Australian sub-continent with a high prevalence of peanut butter allergy among children (Beyer et al., 2001).

In the UK, the current prevalence percentage stands at 5%, which according to the reports has increased by nearly 500% in the last few decades. The main reasons cited by researchers for the increasing prevalence include; environmental factors, adoption of foreign diets and geographical differences.

In addition to, a percentage of 5.2% was observed in Japan (Yoneyama & Ono, 2002), where the most common food which leads to allergy is an egg. This leads to food allergy among 50% of 3-year-old and 66% of 5 years old (Eggesbo, Botten, Halvorsen, & Magnus, 2001).

Highest food allergy among school going children in Mosambique
Food allergy Prevalence in school-aged children > 5 years ( Sources: Prescott et al, 2013)

Another case country included in the study in Africa. Even though the overall prevalence was found to be 3.5%, the prevalence has increased by 18% among children during the last decade among children (Gray & Kung, 2012).

Furthermore, as compared to all the case countries, India reflects the lowest prevalence of food allergy which is as low as 1-2% with prevalence found more among children when to compared to adults (Mahesh et al., 2016). Common food allergies in the case countries are reflected in the table below:

Most common food allergens across case countries


Common Food Allergy

India Peanut, Calcium Rich food, fish, tree nuts, shellfish
USA Milk, eggs, fish, peanuts, wheat, soybeans, and tree nuts like almond, pecans and walnuts
UK Peanut, Tree nut, fruits, fish
Africa Seafood, cow’s milk, egg, wheat
Australia Peanut, Tree nut, Dairy products, hens egg
Japan Egg, Gluten, Meat products, Dairy products, Wheat

Diagnosis of food allergy

Food allergies can only be detected when IgE mediated reactions are instigated within 1-2 hours of allergic food item’s consumption. Oral food challenge (OFC) is specifically a highly accurate diagnostic test for food allergy. The basic procedure behind the test is that the allergist feeds the patient with suspect food in specific doses in order to trigger symptoms. This is a step-wise process since the observed period of time is noted after a specific amount of food is given to the patient.

Once the patient starts showing symptoms, the process is stopped. This is considered one of the safest diagnostic procedures since reactions from this challenge are mild (FARE, 2016). The three common oral food challenges are:

  • Double-blind, placebo-controlled food challenge,
  • Single blind food challenge
  • Open food challenge (Davis, 2009).

The difference between the three diagnostic tools lies in the awareness about the diet given to both patient and doctor. In a double-blind, placebo-controlled food challenge, both the patient and the doctor is unaware of the food product being administered leading no scope of preconceptions. On the other hand, in case of single-blind, only the doctor is aware and in case of an open food challenge, both the patient and doctor is aware of the product being administered, making it the least effective method of all (Davis, 2009).

In fact, an open food challenge is the most common test used across all the case countries. Furthermore, other tests include intradermal test, skin prick test, blood test, and trial elimination diet  (Institute of Allergy & Diseases, 2010).

Therapeutic considerations

One of the most effective ways to manage a food allergy is to avoid eating food that triggers an allergic reaction. So, given the future and current public health, prevention and treatment of allergic reactions triggered by food is a major challenge. Further, intramuscular epinephrine (IM) is considered as the first line therapy, which can reverse the symptoms of anaphylaxis.

Furthermore, other related treatments for food allergy include, bronchodilators (albuterol), Nebulized solutions in case of children, H1 antihistamine (diphenhydramine), supplement oxygen therapy, IV Therapy (FARE, 2016). Further, allergen-specific immuno-therapies are also available which include, oral immunotherapy (OIT), sublingual immunotherapy (SLIT), and Epicutaneous Immunotherapy (EIT) (Glick, 2014).

Increasing food allergy with a change in lifestyle

In conclusion, 10% of the world population is affected by food allergy. This is mainly due to changing lifestyle, excess use of processed foods, new trends affect the diversity of the food consumed are the main causes of increment in the food allergy. Careful monitoring during the diagnosis of patient medical nutrition therapy is important for the effective diagnosis of the disease. There are several studies which point new treatment options and preventive strategies in order to reduce the financial and socio-economic burden of food allergy.



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