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Food allergy or intolerance? The devil lies in what you eat

Food allergy or intolerance? The devil lies in what you eat

We often hear that our food can be someone else’s poison. What if something innocuous that we ate turned right against us and created distressing reactions inside us – every time?
An illustration of a person suffering from adverse reactions to food such as allergies or intolerances
Representative image | Shutterstock

The main difference between food intolerances and food allergies regards the symptoms they generate. Food intolerances affect the gastrointestinal tract, while allergies can present all over the body as an auto-immune response. Let’s take two examples:

Sudheer K. of Bengaluru, after arriving in the United States, suffered an upset tummy and diarrhoea every time he consumed milk items there. Eventually, he had to give up having most milk-based Indian sweets as a result of his troubles. He has lactose intolerance.

Then consider three-year-old Mohit who, during a 10-hour flight from Bengaluru to London, ate a piece of chocolate cake that the flight attendant gave him. After a couple of bites, Mohit started crying: His lips turned red, swollen and began to itch. The condition subsided after a while but Mohit’s father, a physician in the UK, confirmed from a blood test that the child was allergic to walnut – it was in the cake he had eaten in-flight.

Food allergies and intolerances spell a difficult time to many people. In extreme cases, if left unchecked or undiagnosed, it could result in diarrhoea that could fatally compromise organ systems.

Those who are predisposed to either food allergies or food intolerances must follow different regimens depending on the severity of the affliction. But first, an individual must know what differentiates a food allergy from food intolerance, says Dr Anju Sood, Bengaluru-based Clinical Nutritionist.

“A food intolerance is a physical reaction which happens when we consume a certain food which causes signs and symptoms which are not very severe,” she says.

“However, a true food allergy affects the immune system, triggering symptoms ranging from the manageable to the severe. In contrast, food intolerances often confine themselves to the gastrointestinal tract, presenting less severe symptoms,” she says.

Difference between food allergies and food intolerances

While food intolerances are caused by the absence or low amounts of necessary enzymes in our body, a food allergy is caused due to certain chemical substances in the food which the immune system sees as a threat. Symptoms of food intolerance appear after a time interval and can be managed. Whereas with a food allergy, the symptoms show up almost immediately, and severe cases need medical intervention.

External ‘threat’

“A food allergy occurs when the body’s immune system, which under normal circumstances helps one to fight infections, sees the food being consumed as an external threat,” explains Dr Sood.

“Certain protein markers in the food an individual is allergic to instigate the immune system into kicking off the same defence mechanism reserved for microbes and viruses. While most food allergies come with manageable symptoms, however, in extreme cases if treatment is delayed could lead to a fatal state, sometimes giving rise to a situation called anaphylaxis.”

Anaphylaxis, according to National Health Service, Scotland, is a severe, potentially life-threatening allergic reaction, that develops rapidly.
This is caused by the body’s release of a chemical called histamine.

“We have seen people who are severely allergic to seafood like prawns presenting themselves with severe cases of anaphylaxis”, said Dr. Ajay Agarwal, Director and Head of Department, Internal Medicine, Fortis Hospital Noida.

Signs of anaphylaxis can also present themselves with food allergies. These include:

  1. Swollen extremities, eyes, and lips
  2. Faintness
  3. Swelling of mouth (otherwise known as angioedema), swelling of the throat and tongue, causing breathing and swallowing difficulties
  4. Wheezing
  5. A fast heartbeat
  6. Unconsciousness and collapse
  7. Abdominal pain, nausea and vomiting.

“Some people are allergic to peanuts, and they present with severe anaphylaxis, in such cases, keeping an EpiPen is advised”, said Dr. Agarwal.

Damage to the gut

“There is a medical condition called leaky gut,” Dr Sood tells us. “It can be caused due to both food allergies as well as food intolerances but is more prevalent for food allergies” she shares. “When the allergic food is taken in, it ruptures the intestinal lining, making it porous.”

According to her, “The interior of your digestive tract is normally shielded from your immune system. But if the barrier becomes leaky, then the microbes in the food seep through, triggering a hostile response.”

A remedy to this is in having a diet that is fully free from allergy-causing foods and to that can repair the damaged lumen with supplements. Fermented foods like yoghurt, and fish oil are less likely to irritate the gut.

Triggers in childhood

These are some of the most common food allergies in children:

  • Milk
  • Shellfish
  • Fish
  • Tree nuts (Brazil nuts, walnuts, almonds, etc.)
  • Peanuts
  • Eggs
  • Yam

A significant number of children suffering from food allergies experience eczema during infancy.

Allergens in adults

Based on the nature of the symptoms, you can distinguish between a food intolerance or a food allergy.
Among adults, the most common food allergies include

  • Shellfish (lobster, crab or prawn)
  • Peanuts
  • Tree nuts
  • Fruits (apples and peaches)
  • Fish
  • Lactose [milk and milk products

Asthma, angioedema (swelling of mouth), urticaria (otherwise known as hives), hay fever and eczema are the most common symptoms of food allergies in adults.

Although the fact remains that food allergies can be caused by any foodstuff you consume, Health Canada has identified these 10 top-priority food allergens.

  1. Cow’s milk (lactose allergy)
  2. Egg
  3. Peanut
  4. Sesame seed
  5. Tree nuts
  6. Fish, including shellfish
  7. Gluten in wheat, barley, and rye
  8. Soy
  9. Mustard
  10. Food additives like sulphite

If you suffer from food allergies, the recommended course of action is to identify if you are allergic to these and exclude them from your diet.

There are three types of food allergies depending on symptoms, and occurrence.

  1. IgE-mediated food allergySymptoms occur within a few seconds to minutes after consuming the allergen and are triggered by the immune system producing immunoglobulin E (IgE). This is the most common type of food allergy and the most dangerous, as it has higher risks of anaphylaxis. IgE-mediated food allergies are characterised by urticaria (hives), oral allergic syndrome, asthma, anaphylaxis etc.
  2. Non-IgE mediated food allergyThis is caused due to cells in the immune system other than immunoglobulin E. The mechanism of non-IgE mediated food allergies is not clearly understood and is harder to detect as symptoms occur after several hours.Examples include allergies to cow’s milk and soy proteins in infants and wheat allergy in older children. Non-IgE mediated allergies usually appear as cutaneous reactions (skin conditions that result from drug interactions) like contact dermatitis, atopic dermatitis, herpetiform dermatitis, etc.
  3. Mixed IgE & non-IgE mediated food allergiesDespite their prevalence, mixed IgE and non-IgE mediated food allergies are not diagnosed early. This is because the diagnosis is mainly clinical, and the symptoms appear late.


What is food intolerance?

Food intolerance is characterised by difficulty in digesting certain foods. The symptoms include stomach pain, bloating, wind (flatulence) and diarrhoea. Symptoms may also include itching and skin rashes.

Managing food intolerance lies in zeroing in on the food substance you are intolerant to. This would include completely stopping its consumption, and then reintroducing small quantities of it in your diet. This is to know your threshold – that is, how much of it you can consume without developing symptoms.

Today there are several tests to ascertain one’s food intolerances, but none are clinically approved. The best way to find out if one has a food intolerance is to monitor symptoms and the foods you consume. Note down what happens when you stop consuming disagreeing food for a long time. And note down what happens when you have it again later in small amounts.

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