Food Allergies FAQ

Food allergies affect 8% of children and 10% of adults globally. Here we address the common questions people have about food allergies. Note the Big 8 food allergens.  

Food allergies are one of the most common medical issues that we encounter every day. Though it has been prevalent through ages, with new tests and increased awareness and incremental use of additives and synthetic food, the prevalence has increased. Many of us feel bloated and uneasy after eating a certain food item or have a child that reacts to certain ingredients.

Food allergies happen when the immune system erroneously identifies some proteins in the food as harmful and therefore triggers an allergic reaction on consumption of those food items. The adverse reactions may be mild symptoms like rash or digestive discomfort or severe/possibly life-threatening like anaphylaxis (severe allergic reaction with breathlessness, loss of consciousness or death). There is now increasing evidence that food allergy is a complex trait influenced by genetics, environment, and genome-environment interactions.

What are the symptoms of a food allergy?

Symptoms can vary depending on the individual and the type of allergic reaction but commonly include:

• Skin rash/hives/eczema
• Itching in and around the mouth, lips, tongue, or throat
• Swelling in the lips, tongue, or face
• Difficulty swallowing or breathing
• Gastro-intestinal symptoms like abdominal pain, nausea, vomiting, bloating, gas or diarrhea
• Dizziness or light headedness
• Anaphylaxis which is a severe allergic reaction with breathing difficulty due to throat constriction, swelling of the throat or tongue, hives, and a rapid drop in blood pressure, loss of consciousness and even death...

What are the most common food allergens?

There are nine most common causes of food allergies. Of these, the "Big 8” are responsible for 90% of food allergies:

1. Milk: Casein and whey in dairy products (It is different from lactose intolerance).
2. Eggs: Proteins found in egg whites and yolks.
3. Fish: Proteins like parvalbumin found in various fish species (Often severe and persistent lifelong).
4. Crustaceans: Shellfish such as crabs, lobsters, and shrimp.
5. Tree Nuts: Almonds, cashews, and walnuts.
6. Peanuts: A legume that may cause severe allergic reactions.
7. Soy: Proteins found in soybeans and soy products.
8. Wheat: Gluten proteins present in wheat and wheat-based products.
9. Fruits and Vegetables: Adults may have allergy syndrome or pollen-food allergy syndrome where the body’s immune system can mistake certain proteins in fruits and vegetables for the proteins found in pollen thus triggering an allergic reaction after eating raw fruits or vegetables.

How common are food allergies?

Food allergies affect approximately 4% of adults and 4–6% of children. Food sensitization (the body's reaction to a food allergen) is found in over 25% of adults and nearly 20% of children in India.

There has been a notable increase in food allergies over recent decades. Various factors, including changes in diet, environmental exposures, and lifestyle, are being investigated as potential contributors to this rise.

Types of food allergies

1. IgE-mediated food allergy – this is the most common type, triggered by the immune system producing an antibody called immunoglobulin E (IgE). Symptoms occur a few seconds or minutes after eating. This type has a higher risk of anaphylaxis.
2. Non-IgE-mediated food allergy – these allergic reactions aren’t caused by immunoglobulin E, but by other cells in the immune system. This type of allergy is often difficult to diagnose as symptoms take much longer to develop (up to several hours).
3. Mixed IgE and Non-IgE-mediated food allergies – this may include symptoms from both types.

Can food allergies develop later in life?

Yes! Most food allergies develop during childhood, but adults may also develop food allergies, even to foods they have previously consumed without issues. Adult-onset food allergies are more commonly associated with allergens such as shellfish, tree nuts, peanuts, and fish.

Some adults may also experience oral allergy syndrome which exhibits as itching or swelling of the mouth and throat after consuming certain raw fruits or vegetables.

A family history of allergies or asthma can increase the risk of developing food allergies.

Can food allergies be outgrown later in life?

Some children may outgrow certain food allergies, particularly those to milk, egg, soy, and wheat. However, allergies to peanuts, tree nuts, fish, and shellfish are less likely to be outgrown and often persist into adulthood. Additionally, adults can develop new food allergies, even to foods they previously tolerated without issues.

Why have adult-onset allergies increased?

We now see many people developing allergies to food items during adulthood. It is increasing common even in India to see people being diagnosed as allergic to gluten in adulthood while they may have eaten gluten through their childhood. There may be many reasons contributing to that. Let’s understand the possible causes.

Change in diet:
Fast food, processed foods, and some components (like soy) are being consumed in greater quantities, which may be a contributing factor. Due to the adoption of Western lifestyles brought about by urbanization, people may be less exposed to traditional Indian cuisines and cooking techniques, which could have an effect on their immune systems. The substitution of refined sugars and starches for diets that contain fiber (prebiotics), which feeds the gut bacteria is also being investigated as a potential cause of the rise in adult-onset allergies.

Environmental factors:
The severe air and water pollution in India is known to affect and impair immunity. Allergies may become more likely as a result. A "hygiene hypothesis" contends that living in overly hygienic surroundings may result in a less varied gut microbiota and a compromised immune system, which would make people more prone to allergies.

Genetic predisposition:
Some people may have a genetic predisposition to developing allergies, and this could be exaggerated by environmental factors.

Vitamin D deficiency:
Vitamin D plays a vital role in immune function. Its deficiency which is becoming very common may increase the risk of allergy.

Increased awareness, access and diagnosis:
The prevalence of food allergies may rise significantly as more cases are discovered and diagnosed as knowledge of them grows.

The physiological pathway changes:
People are more likely to acquire allergies as they age because of changes in the immune system. The gut microbiome also changes as people age. Numerous studies have examined the relationship between our sensitivity to meals and the health of our gut and the bacteria that live there.

Drug treatments:
Food allergies may also become more likely as a result of certain drugs. In addition to increasing IgE antibodies and disrupting the gut microbiome, acid-suppressive medications (such as proton pump inhibitors and H2-receptor antagonists) are known to reduce the production of acid, which in turn affects how food proteins are broken down. This can result in incomplete digestion and increased exposure of undigested proteins to the gut lining. Increasing and frequent use of antibiotics, among other drugs, can kill both harmful and helpful bacteria in the stomach, disrupting the gut microbiota and contributing to food allergies.

What is the difference between food allergy and food intolerance?

Food allergies are different from food intolerances, which are digestive issues that don't involve the immune system. Food intolerance happens when a person has difficulty in digesting specific foods or ingredients. This is mostly due to a lack of specific enzymes or sensitivities to certain chemicals. Symptoms usually occur a few hours after consuming the concerned food item and include bloating, gas, diarrhea, abdominal pain, and sometimes nausea, headaches, or fatigue.

A few examples are:

• Lactose intolerance (difficulty digesting lactose in dairy products)
• Gluten intolerance
• Sensitivity to certain additives or chemicals in food like Ajinomoto.

How much of a food allergen does it take to cause a reaction?

The amount of allergen required to trigger a food allergy differs from person to person. Sometimes a trace amount of a food allergen, e.g.as little as 1/44,000 of a peanut kernel, can trigger a reaction in highly allergic people.

How long does it take for a reaction to start after eating a food?

Food allergies may occur within minutes to few hours after consumption of the allergen.

General Timeline: Most food allergy symptoms whether mild or severe may develop within minutes to two hours after consuming the food.

Delayed Reactions (rare): In rare cases the symptoms might appear several hours after eating the food.

Anaphylaxis: It is a severe/life-threatening allergic reaction that may occur within minutes of exposure to an allergen. Occasionally it may occur half-hour or longer after exposure.

Who is most at risk for a severe allergic reaction to food? Other conditions that put you more at risk (known associations)?

Family History: People who have a family history of allergies, asthma, or eczema have increased odds of developing food allergies.

Asthma: Generally, people who have Bronchial asthma are at a higher risk of anaphylaxis, a severe allergic reaction.

Occurrence of Anaphylaxis previously: People who have experienced anaphylaxis before have an increased risk of severe reactions in the future too.

History of Allergies to Other Substances: People who are allergic to pollen, dust, or other substances are at higher risk of developing food allergies.

Skin issues like Eczema: People with eczema are known to be at a significant risk for developing food allergies, especially children.

Age: Although food allergies may develop at any age, they are most common in children, more so those under three years of age.

How are food allergies diagnosed?

Diagnosis typically involves a sequence of steps including:

• Review of medical history of the patient: Doctors discuss the symptoms and potential triggers with the patient.
• Diagnosis through elimination technique: Doctors may suggest temporarily removing suspected allergens from the diet to observe if there are any changes in symptoms.
• Skin prick tests: Assessing the immune system's response to specific allergens. During a skin-prick test, a few drops of standardized extracts of foods are placed on the arm. The skin is then pierced with a small needle (lancet), which allows the allergen to come into contact with the cells of your immune system. Itching, redness and swelling usually indicates a positive reaction. This test is usually painless.
• Blood test: Measures the amount of allergic antibodies in the blood.
• Oral food challenges: This is done by a doctor where the patient consumes small amounts of the suspected allergen and is monitored for reactions.

What is the treatment for food allergies?

There is currently no cure for food allergy. The primary treatment for food allergies is strict avoidance of the identified allergens.

Two medications which are used are: Antihistamines which are used to treat mild to moderate allergic reaction and Adrenaline/epinephrine that is used to treat severe allergic reactions.

Epinephrine Auto Injectors: People who are known to have an increased risk of severe reactions must always carry an epinephrine auto-injector, also known as an Epi-pen.

Newer Medications:

Peanut allergen powder is an oral immunotherapy product approved in patients 4-17 years of age for the mitigation of allergic reactions, including anaphylaxis, that may occur with accidental exposure to peanut, but its benefits are restricted to peanut allergy.

Omalizumab is the first FDA-approved medication in the US to reduce allergic reactions to more than one type of food after accidental exposure. Omalizumab is a drug (in the class of drugs called monoclonal antibodies) that binds to immunoglobulin E (IgE), the antibody type that triggers allergic reactions, and blocks IgE from binding to its receptors.

What to watch out for in food labelling?

Generally, when checking food labels for food allergies, one should look for clear declarations of the nine most common allergens (milk, eggs, wheat, soy, peanuts, tree nuts, fish, shellfish, and sesame) in both the “ingredient list” and the "contains" section.

The "Contains" Section:
Food manufacturers are required to list the nine major allergens in a clear "contains" statement. Example: "Contains milk, wheat, and soy".

Ingredient List Section:
The name of the food source of a major allergen must appear in parentheses following the name of the ingredient. Example: "Lecithin (soy)".

Sometime the allergens may not be apparent immediately and maybe hidden in unexpected places, so one should review the entire ingredient list.

Precautionary Allergen Labelling (PAL):
"May Contain": This phrase indicate that a product may contain an allergen due to potential cross-contamination during manufacturing or packaging, e.g.: "May contain traces of peanuts," or "Made in a facility that also processes tree nuts".

Living with food allergies
As we have established clearly there is no cure for food allergies. Lots of children do outgrow some allergies like allergy to milk and eggs. The best way to prevent an allergic reaction is to remove the offending food (allergen) from their diet.

Remove offending allergen from food: Removing eggs or peanuts from a child’s diet can be difficult for parents, however both these good sources of protein can be replaced by other, alternative sources.

A milk allergy can have more of an impact on nutrition as milk is a good source of calcium, use other ways to incorporate calcium into the child’s diet like green leafy vegetables. Many foods items and drinks are also fortified with extra calcium.

Read food labels properly: It’s very important to check the label of any pre-packed food or drinks to check if it contains ingredients, they’re allergic to.

Inform the eatery/restaurant and choose menu wisely when going out to eat keeping the food allergies in mind.

Always carry an Epi-pen to combat any severe reaction.

Citations

1. ACAAI. “Food Allergy.” ACAAI Patient, 2022, acaai.org/allergies/allergic-conditions/food/.
2. “Common Food Allergies: Causes, Symptoms & Treatment - FICSI.” Ficsi Blog - Ficsi Blog, 14 Mar. 2024, www.ficsi.in/blog/most-common-food-allergies-understanding-allergen-cau….
3. “FDA Approves First Medication to Help Reduce Allergic Reactions to Multiple Foods after Accidental Exposure.” FDA, 16 Feb. 2024, www.fda.gov/news-events/press-announcements/fda-approves-first-medicati….
4. “Food Allergies.” NHS Inform, www.nhsinform.scot/illnesses-and-conditions/nutritional/food-allergy/.
5. Lifestyle, Senior. “Food Allergies in Seniors and What to Do about Them.” Senior Lifestyle, 14 Mar. 2023, www.seniorlifestyle.com/resources/blog/food-allergies-seniors/.
6. “Living with Food Allergies - Caring & Prevention | FARE.” FoodAllergy.org, Mar. 2025, www.foodallergy.org/living-food-allergy.
7. Mitre, Edward, et al. “Association between Use of Acid-Suppressive Medications and Antibiotics during Infancy and Allergic Diseases in Early Childhood.” JAMA Pediatrics, vol. 172, no. 6, 4 June 2018, p. e180315, www.ncbi.nlm.nih.gov/pmc/articles/PMC6137535/, https://doi.org/10.1001/jamapediatrics.2018.0315. Accessed 14 Sept. 2020.
8. Priyanka Dadha, et al. “Reported Food-Related Symptoms and Food Allergen Sensitization in a Selected Adult Population in Hyderabad, India: A Hospital-Based Survey.” Journal of Allergy and Clinical Immunology. Global, vol. 3, no. 2, 1 May 2024, pp. 100204–100204, https://doi.org/10.1016/j.jacig.2023.100204. Accessed 14 July 2024.
9. Sehgal, Shruti, et al. “Understanding the Burden of Food Allergy among Urban and Rural School Children from North India.” World Allergy Organization Journal, vol. 17, no. 6, June 2024, p. 100916, https://doi.org/10.1016/j.waojou.2024.100916. Accessed 23 Nov. 2024
10. “Food Labels: Read It before You Eat It!” Aaaai.org, 2023, www.aaaai.org/tools-for-the-public/conditions-library/allergies/food-la….
11. Odisho, Nora, et al. “Food Allergy: Labelling and Exposure Risks.” Journal of Food Allergy, vol. 2, no. 1, 1 Sept. 2020, pp. 115–118, https://doi.org/10.2500/jfa.2020.2.200027.