Understanding food allergies and sensitivities

Understanding food allergies and sensitivities can be challenging because symptoms manifest quickly after exposure. What’s more, the reactions tend to be delayed only to be noticed a few days after the exposure. So, this makes it difficult to track and identify the source of such a reaction. This article will help you understand food allergies and sensitivities. You will be able to differentiate between food allergies and food sensitivities.

Food allergies-Understanding food allergies and sensitivities

Food allergies are immune system responses triggered specific proteins. The immune system mistakenly identifies certain proteins as harmful and releases antibodies (IgE) to fight against them. Some of the common food allergens include peanuts, tree nuts, milk, eggs, fish, shellfish, soy, and wheat. So, food allergies can cause:

  • Hives
  • Itching
  • Swelling (face, lips, tongue, or throat)
  • Respiratory issues (wheezing, shortness of breath)
  • Gastrointestinal problems (nausea, vomiting, diarrhea)
  • And in severe cases, anaphylaxis—a life-threatening reaction


This condition can be diagnosed through medical history, physical examination and allergy testing, such as skin prick tests or blood tests (measuring specific IgE antibodies).


The primary treatment for food allergies is strict avoidance of the allergen. So, individuals with severe allergies may carry epinephrine auto-injectors (e.g., EpiPen) to counteract severe allergic reactions.

Food sensitivities

Food sensitivities involve non-immune responses to certain foods. So, food sensitivity occurs when the digestive system is unable to process certain components of food.

Common Sensitivities

Lactose (milk sugar) intolerance

Gluten (a protein found in wheat, barley, and rye)

Sensitivity to food additives (such as sulfites or monosodium glutamate)


  • Bloating
  • Gas
  • Abdominal pain
  • Diarrhea
  • Nausea
  • Headaches
  • Skin rashes
  • And general discomfort


Diagnosis involves self-reporting symptoms and keeping a food diary to identify potential triggers.

You can also eliminate diets. Temporary elimination of foods can help identify the offending foods.


Treatment may involve avoiding or reducing the intake of the trigger food or component. Moreover, enzyme supplements (e.g., lactase for lactose intolerance) or over-the-counter medications can help manage symptoms.

Here are some of the factors that contribute to food allergies and sensitivities:

1. Immunological Response

Food allergies occur when the immune system mistakenly identifies certain proteins in food as harmful substances. The immune system produces an allergic response, releasing chemicals such as histamine that cause allergy symptoms. The specific proteins, called allergens, vary depending on the food and individual.

How does it happen?

  • Sensitization-The first exposure to an allergenic food triggers the immune system to produce antibodies immunoglobulin E (IgE) antibodies. These antibodies are designed to recognize and neutralize harmful substances. However, if it’s a food allergy they mistakenly target harmless food proteins as threats.
  • Activation– when you are exposed to the same food the IgE antibodies recognize the food proteins and trigger the release of chemicals. So, chemicals such as histamine from immune cells called mast cells are released. This process is known as mast cell degranulation.


Skin reactions include:

  • Itching
  • Hives
  • Eczema
  • And swelling (angioedema).

Gastrointestinal issues

  • Nausea
  • Vomiting
  • Abdominal pain
  • And diarrhea

Respiratory problems

  • Sneezing
  • Runny nose
  • Nasal congestion
  • Wheezing
  • Or difficulty breathing

Cardiovascular symptoms

  • Drop in blood pressure
  • Lightheadedness
  • Or fainting


In other cases, the allergic reaction can progress to a severe and potentially life-threatening condition. This condition is known as anaphylaxis. Anaphylaxis involves a massive release of chemicals throughout the body causing a sudden drop in blood pressure. Moreover, this can lead to difficulties in breathing and constriction of the airways. Anaphylaxis  require immediate medical attention .

2. Early Exposures and Sensitization

Introducing certain foods early in life, particularly during infancy, may increase the risk of developing allergies. This concept is known as the “allergy march” or “atopic march.” For example, if a child has eczema, early exposure to certain foods like peanuts or eggs may increase their risk of developing allergies to those foods.

Diagnosis-Understanding food allergies and sensitivities

It involves a comprehensive evaluation by a healthcare professional. The process may vary depending on the specific type of exposure or allergen being investigated. Here are some common steps that might be involved in the diagnostic process:

Medical History

The healthcare professional will start by taking a detailed medical history. This may include any known or suspected exposures to allergens or substances. So, they will inquire about symptoms that occur after exposure, such as respiratory problems. Also, the doctor will inquire about skin reactions or other allergic reactions.

Physical Examination

A physical examination may be conducted to assess any visible signs or symptoms associated with exposures or sensitization. So, the healthcare professional will carefully examine the affected areas or any specific symptoms reported by the individual.

Allergy Testing

Allergy testing is commonly used to identify sensitization to specific allergens. There are different types of allergy tests, including skin tests and blood tests.

Skin Tests

Skin prick tests or patch tests can help identify immediate or delayed allergic reactions to various substances. During a skin prick test, small amounts of allergens are applied to the skin with a tiny needle prick or a small scratch. If a person is sensitized to a particular allergen, they may develop a localized allergic reaction at the test site.

Blood Tests

Blood tests, such as specific IgE (immunoglobulin E) tests or component-resolved diagnostics, can measure the presence and levels of allergen-specific antibodies in the blood. These tests can help determine if an individual has developed sensitization to specific allergens.

Elimination Diets or Provocation Tests

In some cases, an elimination diet or provocation tests may be used to identify sensitivities to food or chemical substances. Under medical supervision, certain foods or substances are removed from the diet or reintroduced to assess the body’s response.

Symptom Assessment

The healthcare professional will assess the individual’s symptoms and their relationship to specific exposures or allergens. This evaluation may involve keeping a symptom diary or utilizing other methods to track symptoms and identify patterns.

3. Gut Health and Microbiomes

The gut plays a crucial role in the development and regulation of the immune system. Disruptions in the gut Microbiomes, such as imbalances in gut bacteria or a compromised gut barrier, may contribute to food sensitivities and allergies.

So, allergies can disrupt gut health through several mechanisms:

Intestinal Permeability

Allergic reactions can lead to increased intestinal permeability. This is often referred to as “leaky gut.” So, this means that the lining of the intestines becomes more porous, allowing substances to pass through that would normally be prevented. This increased permeability can contribute to digestive symptoms and may allow allergens to enter the bloodstream, triggering an immune response.


Understanding food allergies and sensitivities

Allergic reactions cause inflammation in the body. This is more common along the gastrointestinal tract. Moreover, chronic inflammation can disrupt the balance of the gut Microbiomes and affect overall gut health.

Altered Motility

Some individuals with allergies, such as eosinophilic esophagitis (EOE) or food allergies, may experience changes in gut motility. This can result in symptoms such as abdominal pain, bloating, and altered bowel habits.

Microbiome and Allergies

The gut microbiomes play a crucial role in immune regulation and can influence the development of allergies. Several studies have shown associations between alterations in the gut microbiota and increased risk of allergies. Therefore, it’s important to note that the exact cause-and-effect relationship between the microbiome and allergies is still being investigated.


Reduced microbial diversity in the gut  increases risk of developing allergies. A diverse and balanced gut microbiome is generally associated with better immune regulation and decreased susceptibility to allergic conditions.

Microbial Metabolites

The metabolites produced by gut bacteria can interact with the immune system and influence its response. Also, certain metabolites derived from specific bacterial strains can promote immune tolerance and help protect against allergies.

Early Life Factors

The composition of the gut microbiome in early life may impact the development of allergies. Factors like mode of delivery (vaginal vs. cesarean section), infant feeding practices (breast milk vs. formula), antibiotic use, and exposure to environmental microorganisms can influence the establishment of a healthy microbiome and potentially affect the risk of allergies later in life.


It involves gut health and the Microbiomes often require a comprehensive approach, considering clinical symptoms, medical history, and specialized tests. These may include:

Allergy Testing-

Understanding food allergies and sensitivities

Allergy tests, such as skin prick tests or blood tests (specific IgE), can identify specific allergens triggering an immune response. These tests are useful for diagnosing IgE-mediated allergies, such as hay fever or food allergies.

Food Elimination Diet

An elimination diet may be recommended in cases of suspected food allergies or sensitivities. This involves removing potentially problematic foods from the diet and reintroducing them one by one to identify any triggers.

Gut Microbiome Analysis

Analyzing the composition and diversity of the gut microbiome can provide insights into the overall gut health and potential imbalances. This can be done through techniques such as DNA sequencing of microbial DNA in stool samples.

Biomarker Analysis

Researchers are investigating various biomarkers associated with allergies and gut health. For example, fecal calprotectin levels can indicate inflammation in the gastrointestinal tract.

Emerging research suggests that a healthy gut microbiome is important in preventing the development of allergies.

4. Environmental Factors

Environmental factors, such as pollution, exposure to certain chemicals, and changes in dietary patterns, may also influence the development of food allergies and sensitivities. These factors can interact with genetic predispositions and impact the immune system’s response to food proteins. Diagnosis entails:

Medical History

Your doctor will ask you detailed questions about your symptoms, their duration, and any factors that seem to trigger or worsen your allergies. They will also inquire about your living environment, occupation, hobbies, and any recent changes in your surroundings.

Physical Examination

A physical examination helps to assess your overall health and look for any visible signs of allergic reactions such as skin rashes or nasal congestion.

Allergy Testing

There are two main types of allergy tests:

  • Skin Prick Test– This test involves placing a small number of specific allergens on your skin,usually on your forearm or back, and then pricking or scratching the skin to allow the allergen to enter. If you are allergic to a particular substance, you will develop a small raised bump or a red, itchy reaction at the site.
  • Blood Test– A blood test, such as the specific immunoglobulin E (IgE) test, measures the level of antibodies produced in response to specific allergens in your blood. This test can help identify allergens causing allergies, including environmental triggers.

Environmental Assessment

To identify the environmental factors contributing to your allergies, your doctor may recommend an environmental assessment. This involves evaluating your living or working environment for potential allergens such as dust mites, mold, pollen, pet dander, or chemicals. This assessment may include:

  • Indoor Air Quality Assessment-This involves assessing air quality in your home or workplace for common allergens, pollutants, and irritants. This may involve testing for mold, dust mites, volatile organic compounds (VOCs), or other airborne allergens.
  • Allergen-specific Testing-In some cases, you may specific testing for particular allergens. For example, if you suspect a pet allergy, your doctor may recommend testing for specific animal allergens.
  • Patch Testing-Your doctor may perform Patch testing to identify contact allergens that cause skin reactions, such as allergic contact dermatitis. Moreover, the doctor then applly small amounts of potential allergens, on your skin for a specific duration to see if any reactions occur.

Symptom Tracking

Keeping a diary of your symptoms and their severity can help identify patterns and potential triggers over time. Note any changes in symptoms based on exposure to specific environments or activities.

5. Cross-Reactivity

Cross-reactivity occurs when the proteins in one food resemble the proteins in another food, leading to an allergic response. For example, if someone is allergic to birch pollen, they may also experience allergic reactions to certain fruits, such as apples or peaches, due to cross-reactivity between the proteins. Diagnosis involves:

Medical history

The doctor will ask detailed questions about your symptoms, their onset, duration, and any potential triggers. They will also inquire about any known allergies you have and your exposure to different substances.

Physical examination

understanding food allergies and sensitivities requires some physical examinations. So, the doctor may perform a physical examination to check for any visible signs of allergic reactions, such as rashes, swelling, or redness.

Allergy testing

There are two main types of allergy tests that can help determine cross-reactivity allergies:

  • Skin prick test –In this test, a doctor may prick into the skin small amounts of different allergens usually on the forearm or back. If you’re allergic to a particular substance, you will develop a raised bump or redness at the site of the prick.
  • A blood test-A blood sample measures the presence of specific immunoglobulin E (IgE) antibodies. The immune system produces IgE antibodies to act on the allergens. The blood test can identify the presence and levels of IgE antibodies for different allergens, helping to identify potential cross-reactivity.

Challenge tests

In some cases, if the diagnosis remains uncertain, an oral food challenge or other challenge tests may be conducted under medical supervision. These tests involve controlled exposure to suspected allergens to observe any allergic reactions.

Specialist consultation

In complex cases, your doctor may refer you to an allergist or immunologist who specializes in diagnosing and managing allergies. They can provide further evaluation, interpretation of results, and additional treatment options.

6. Genetic Predisposition

There is evidence to suggest that genetics play a role in food allergies and sensitivities. If you have a family history of allergies, you may be at a higher risk of developing them as well. However, it’s important to note that genetics alone do not determine whether someone will develop an allergy. Diagnosis involves:

Family History

The first step is to gather information about the allergic conditions present in your immediate and extended family. Allergies tend to have a hereditary component, so knowing if your parents, siblings, or other close relatives have allergies can provide important clues about your own genetic predisposition.

Clinical Assessment

An allergist or immunologist will evaluate your medical history and conduct a comprehensive physical examination. They will ask you about your symptoms, triggers, and any previous allergic reactions you may have experienced. This assessment helps in determining the likelihood of an allergic condition and guides further diagnostic tests.

Allergy Testing as a way of

Understanding food allergies and sensitivities

Allergy testing can help identify specific allergens that trigger an immune response in your body. There are two main types of allergy tests:

  • Skin Prick Test-A small amount of common allergens is pricked into your skin with a tiny needle during this test. So, if you have a genetic predisposition to allergies, your body’s immune system may produce an allergic response, leading to localized redness, swelling, or itching at the test site.
  • Blood Test-A blood sample is taken to measure the levels of specific antibodies, such as Immunoglobulin E (IgE), that are associated with allergic reactions. Elevated levels of IgE antibodies can indicate a genetic predisposition to allergies.

Genetic Testing

Genetic testing may be used to identify specific genetic variations. Remember, mutations cause allergic conditions. This type of testing is less common and usually reserved for cases where the cause of allergies is unclear or when investigating more severe or complex allergic disorders. It can help in diagnosing certain rare genetic disorders linked to allergies.


1. What is the difference between a food allergy and food sensitivity?

A food allergy is an immune system response triggered by specific proteins in food. On the other hand, food sensitivity (also known as a food intolerance) is a non-immune reaction to certain foods, usually due to the body’s inability to properly digest or process certain components, like lactose or histamine.

2. What are the most common food allergens?

The most common food allergens, which account for the majority of food allergies include:
Eggs, Peanuts, Tree nuts (e.g., almonds, walnuts), Soy, Wheat, and fish.

3. What are the symptoms of a food allergy?

Skin reactions (rashes, hives, eczema)
Digestive issues (nausea, vomiting, diarrhea)
Respiratory problems (wheezing, coughing, shortness of breath)

4. How are food allergies diagnosed?

If you suspect a food allergy, it’s essential to see an allergist for a proper diagnosis.

5. Can food allergies develop later in life?

Yes, it is possible for food allergies to develop later in life, even if you’ve consumed the food without issues in the past.