Difference Between Food Allergy, Food Sensitivity & Food Intolerance

January 23, 2023

Food is an important source of energy. Food contains nutrients that are beneficial to meet one’s nutrient deficiencies. However, several food items have proven to be life-threatening for different people.  

One of the most confusing health and nutrition topics is food allergy, sensitivity, and intolerance and how to distinguish them. These three topics have a range of differences, they each even come with a set of distinct definitions. 

These adverse reactions to food come with individual intolerances to otherwise commonly tolerated food 1

And complications are mostly related to:

  • Milk
  • Ghee
  • Egg
  • Peanuts
  • Soy
  • Shellfish
  • Fish
  • Wheat

Let’s start with the very first topic :

What is a food allergy?

Food allergy is not a single disease, nor is it caused by one pathophysiologic disturbance. As such, it can be treated with many different medications, according to the American Academy of Allergy, Antibiotics, and Food Allergy Research (AAARR) website 2

Food allergies are adverse immunologic reactions that might be due to immunoglobulin E (IgE)- or non-IgE-mediated immune mechanisms and can be caused by a variety of factors, such as exposure to food contaminated with bacteria, viruses, parasites, or even small amounts of insect bites 3

More than 80% of food allergies are caused by exposure to tree nuts, shellfish, fish, wheat, sesame seed, and soy. 

It is the protein component, not the fat or carbohydrate component, of these foods that leads to sensitisation and allergy 4.

Food-induced allergic disorders are broadly categorized into those mediated by IgE antibodies or by other mechanisms. 

IgE-mediated allergic responses are the most widely recognised form of food allergy and are characterised by the rapid onset of symptoms after ingestion. During initial "sensitisation" to the food, consumption stimulates the production of IgE antibodies specific to that food which then bind to tissue basophils and mast cells.

Allergic reactions can be caused by exposure to foods that trigger the release of mediators, such as histamine, prostaglandins, and leukotrienes, in the body. When the causal foods are subsequently eaten, they bind to their specific IgE antibodies and cause "clinical reactivity" and allergic symptoms. 

It is important to note that sensitisation can be present without clinical reactivity, meaning that there is no actual reaction to exposure.

Non-IgE-mediated (cell-mediated) food allergy results from the generation of T cells that respond directly to the protein, leading to the release of mediators that direct certain inflammatory responses (e.g., eosinophilic inflammation). Dietary protein-induced reactions typically affect the gastrointestinal (GI) tract and skin and manifest as dietary-protein-induced enterocolitis and proctitis, celiac disease, and its related skin disorder, dermatitis herpetiformis 3 5 6 .

Signs of food allergies:

  • Shortness of breath
  • Weak pulse
  • Anaphylaxis (Severe allergic reactions)
  • Vomiting or stomach cramps
  • Swelling of tongue
  • Repetitive cough 7 

What is Food Sensitivity?

Food sensitivity is a type of immune-mediated response to food. Food triggers mainly IgG, causing inflammation (body’s defence mechanism in response to antigens). This may also contribute to increased symptoms of IBS (Irritable Bowel Syndrome). The response period is however delayed and you can still eat problematic food without any difficulty 8

Food sensitivity symptoms:

As compared to an immune-mediated response, food sensitivity also faces similar symptoms, with a delay in the onset of symptoms and a lack of IgE antibodies on testing 9.

Other symptoms that overlap with systemic discomforts are-

  • Fatigue
  • Headache
  • Musculoskeletal complaints 
  • Diarrhoea
  • Sweating
  • Hives
  • Bloating

What is food intolerance?

Food intolerances are adverse reactions caused by some unique physiologic characteristic of the host, such as metabolic disorders (e.g., lactase deficiency) 3. The cause of intolerance could be an enzymatic defect or the effect of vasoactive pharmacological substances present in food (enzymatic and pharmacological intolerance) 1

Food intolerances can be seen in IBS patients and people with digestive issues. While a food allergy results from an immune system reaction to a specific food, food intolerances usually involve the digestive system, not the immune system 10.

Foods associated with intolerance are gluten, milk, sulfites, and food additives. 

The different types of intolerances are as follows:

  • Lactose intolerance: Lactose intolerance is a condition where people are unable to break lactose down into smaller molecules that the body can easily absorb through the intestine. It can cause spasms, stomach aches, bloating, diarrhoea, gas, and damage to the nervous system 1.
  • Fructose intolerance: Fructose is a sugar present in fruit, some vegetables, and honey. Fructose intolerance can also be due to the lack of an enzyme Aldolase B, although this is rare. In people who are fructose intolerant, the fructose in foods ferments in the gut, leading to gas, fullness, bloating, cramps and diarrhoea 11.
  • Gluten intolerance: Gluten is a protein that is present in grains like wheat, barley and rye which causes intestinal conditions like IBS (Irritable bowel syndrome) and leads to discomfort in those intolerant to gluten 12

Signs of food intolerance:

  • Bloating
  • Excessive gas
  • Headache
  • Migraine
  • Malaise
  • Runny nose
  • Diarrhoea

Table 1: Difference between allergy, sensitivity, and intolerance


(1) Ortolani, C.; Pastorello, E. A. Food Allergies and Food Intolerances. Best Pract. Res. Clin. Gastroenterol. 2006, 20 (3), 467–483. https://doi.org/10.1016/j.bpg.2005.11.010.

(2) Bruijnzeel-Koomen, C.; Ortolani, C.; Aas, K.; Bindslev-Jensen, C.; Björkstén, B.; Moneret-Vautrin, D.; Wüthrich, B. Adverse Reactions to Food. European Academy of Allergology and Clinical Immunology Subcommittee. Allergy 1995, 50 (8), 623–635. https://doi.org/10.1111/j.1398-9995.1995.tb02579.x.

(3) Sampson, H. A. Update on Food Allergy. J. Allergy Clin. Immunol. 2004, 113 (5), 805–819. https://doi.org/10.1016/j.jaci.2004.03.014.

(4) Waserman, S.; Watson, W. Food Allergy. Allergy Asthma Clin. Immunol. 2011, 7 (1), S7. https://doi.org/10.1186/1710-1492-7-S1-S7.

(5) Sicherer, S. H.; Sampson, H. A. Food Allergy: Epidemiology, Pathogenesis, Diagnosis, and Treatment. J. Allergy Clin. Immunol. 2014, 133 (2), 291–307; quiz 308. https://doi.org/10.1016/j.jaci.2013.11.020.

(6) Food Allergy & Anaphylaxis Emergency Care Plan - FoodAllergy.org. https://www.foodallergy.org/living-food-allergies/food-allergy-essentials/food-allergy-anaphylaxis-emergency-care-plan (accessed 2022-12-15).

(7) Food Allergies | Causes, Symptoms & Treatment. ACAAI Public Website. https://acaai.org/allergies/allergic-conditions/food/ (accessed 2022-12-15).

(8) Healthcare, B. W.-B. What’s The Difference Between A Food Allergy and A Food Sensitivity? Balanced Well-Being Healthcare. https://www.balancedwellbeinghealthcare.com/whats-the-difference-between-a-food-allergy-and-a-food-sensitivity/ (accessed 2022-12-15).

(9) Turnbull, J. L.; Adams, H. N.; Gorard, D. A. Review Article: The Diagnosis and Management of Food Allergy and Food Intolerances. Aliment. Pharmacol. Ther. 2015, 41 (1), 3–25. https://doi.org/10.1111/apt.12984.

(10) Food intolerance: Causes, types, symptoms, and diagnosis. https://www.medicalnewstoday.com/articles/263965 (accessed 2022-12-15).

(11) Choi, Y. K.; Johlin, F. C. J.; Summers, R. W.; Jackson, M.; Rao, S. S. C. Fructose Intolerance: An Under-Recognized Problem. Off. J. Am. Coll. Gastroenterol. ACG 2003, 98 (6), 1348. https://doi.org/10.1111/j.1572-0241.2003.07476.x.

(12) Balakireva, A. V.; Zamyatnin, A. A. Properties of Gluten Intolerance: Gluten Structure, Evolution, Pathogenicity and Detoxification Capabilities. Nutrients 2016, 8 (10), 644. https://doi.org/10.3390/nu8100644.

Chandra Biswas

She is specialized in Cell and Molecular biology and is an enthusiastic researcher. She believes in sharing practices which are scientifically researched and proven.

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