Food Allergies and Intolerances

Posted by Elina Dawoodani on Thu, Oct 16, 2014  
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Food Allergies and Intolerances


We all must have come across people, who after consuming specific foods have reported immediate and dramatic reactions such as nausea, vomiting, diarrhoea, cramps, itching, gastro-intestinal problems etc. These are called adverse food reactions.

There are two types of food reactions in general, namely

  1. Food Allergy
  2. Food intolerance

What is food allergy?

A food allergy is an abnormal response to a food by our immune system. It is also known as food hypersensitivity.  There is a vast difference between clinically proven food allergy and people’s perception of it. Scientists describe allergens as those foreign substances which on interaction with the immune system cause allergic reactions. These allergies can at times be fatal, and can even cause life threatening diseases such as anaphylaxis. (ref: 1)

Hence, food allergies have to be taken special care of. Below is a list of symptoms that arise because of food allergens:

Gastrointestinal symptoms

Nausea, gastrointestinal pain, vomiting, colitis, distension, gastrointestinal bleeding, diarrhoea etc

Respiratory symptoms

Cough, airway obstruction, running nose, airway tightening, asthma, wheezing etc.

Skin problems

Itching, eczema, flushing, erythema (skin inflammations), redness, rashes, swelling of blood vessels etc.

Systemic manifestations

Anaphylaxis, hypotension, failure to grow etc.

Neurological behaviour

Headache, irritability, restlessness etc.


The risk factors of food allergy are:

  • Heredity
  • Atopy
  • Antigen exposure
  • Environmental factors
  • Gastrointestinal permeability


The most common allergens are:

  • Eggs
  • Cow’s milk
  • Peanuts
  • Wheat
  • Soya
  • Fish
  • Shellfish and many more.

Let’s move on to the other adverse food reaction:

What is food Intolerance?

Food intolerance is basically a digestive system response. Unlike food allergy, food intolerance doesn’t involve body’s immune system.  It occurs when body is unable to breakdown or digest a particular food and thus shows reactions. It may be triggered by enzyme deficiency (as in the case of lactose intolerance), physical reaction to a food or a food additive.

The factors that cause food intolerance are:

  1. Enzyme deficiency or defects: In this case, food sensitivity occurs because body has difficulty in breaking down a particular constituent of food because it lacks the enzyme required for the purpose.  Some common examples of disorders arising because of this are lactose intolerance, PKU (Phenylketonuria) etc.


  1. Reaction to microbial contamination: Consuming certain type of bacteria can also cause food intolerances. This is mainly seen when spoilt marine fishes are consumed. Ingestion of improperly handled seafood causes scramboid poisoning. Another example of microbial contamination is paralytic shellfish poisoning. The symptoms of poisoning are: headache, burning, tingling, numbness in the extremities, dizziness, abdominal cramps, nausea, palpitations, floating etc.


  1. Natural food chemicals: Natural components of foods may not be easily digested by a few people. Substances which have such chemicals include caffeine, brewer’s yeast, canned fishes etc.


  1. 4.       Food additives: Food additives like preservatives, colouring agents, flavour enhancers etc have shown adverse food reaction in some people.  E.g. yellow colour food dye, monosodium glutamate (MSG) etc.


  1. 5.       Psychological reactions: Some people may develop food intolerance due to a psychological trigger. E.g. unpleasant event in one’s life, certain incident etc.



Diagnosis of food reactions:

The moment you realize that any food is causing you a problem, consult your physician immediately. There are a number of initial screenings that one may go through in order to identify the allergen. These tests include biochemical, immunological testing, radioallergobsorbent test and skin tests.

The other ways to diagnose is checking your history, physical examination and by maintaining food/symptom diary. One of the best ways to identify and rule out the allergen is to follow an elimination diet. The elimination diet is a diet that eliminates a specific food or many such foods that are suspected by your nutritionist as possible allergens.

The most common allergens considered in the elimination diet are:

  • Wheat
  • Dairy products
  • Eggs
  • Corn
  • Soy
  • Citrus fruits
  • Nuts
  • Peanuts
  • Tomatoes
  • Artificial food colours
  • Preservatives
  • Coffee
  • Chocolate and many more

In elimination diet, the above mentioned foods are totally removed from a person’s diet. If the condition improves, then reintroduce the suspected food item and check if the symptoms reoccur. If it does, then re-eliminate the suspect food and the allergen is identified. Take help from your nutritionist to follow this. (ref: 3)

Treatment of food reactions:

The treatment option for allergy management is pretty simple. One should avoid that which causes symptoms, appropriate medications should be used, evaluate for immunotherapy and getting oneself educated.

One also has to be aware about products that contain the allergic ingredient, and find out similar food alternatives.

For example, if someone is not able to digest milk due to lactose intolerance, then he should avoid products that contain milk. Soya milk or lactase treated milk can be consumed since it can be digested in the absence of enzyme lactase.  (ref: 2)

Prevention of adverse food reactions:

  • If there is a family history of allergies, then avoid early introduction of “at risk” foods in children.
  • Reduce dust mite levels in homes.
  • Attend seminars and lectures that educate people about allergy management.
  • Avoid smoking and keep away from places that are polluted by tobacco smoke.
  • Screen yourself for allergies periodically.
  • Avoid touching animals since their hair, scales etc. might contain bacteria that lead to food reactions.
  • Consume only fresh seafood. Avoid storing it for too long.


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