According to NHS(1), food intolerance is „difficulty digesting certain foods and having an unpleasant physical reaction to them”. Food intolerances can also be described as a negative response from the digestive system to certain foods or types of foods. The symptoms of food intolerance vary from bloating, abdominal cramps and pains, excessive gas, nausea, vomiting, heartburn, headache, irritability or nervousness, diarrhoea to skin rashes and itching. Symptoms of food intolerances usually become noticeable after consumption of certain foods and last for a couple of hours after ingestion. The difference between food intolerance and food allergy is that food intolerance does not involve the immune system and symptoms often occur gradually and become noticeable only after ingesting a large number of certain foods. It can also be caused by various types of food. What exactly causes food intolerance remains unknown, however, it is possible to be intolerant to many kinds of food that contain certain nutrients, for example, lactose, gluten, food additives etc. According to Cleveland Clinic(2) food intolerances are found within 10% of Americans. To summarise the main causes of food intolerances are certain foods, that are not tolerated by the body. The cause of that can be the absence of an enzyme required to completely digest the food, irritable bowel syndrome, sensitivity to food additives, celiac disease or even recurring stress or other psychological factors. Symptoms of such allergies are mostly digestive issues that do not involve the reaction of the immune system.
Food allergies are defined by NHS(4) as „A food allergy is when the body’s immune system reacts unusually to specific foods. Although allergic reactions are often mild, they can be very serious”.
According to the National Institute of Allergy and Infectious Diseases(3), food allergies are estimated to affect 4% of adults and 5% of children in the United States. Food allergies differ from food intolerances in the fact that food allergy DOES indeed involve the reaction of the immune system and it can affect different areas of the body, not only the digestive system. The symptoms that can be caused by food allergies are nausea, vomiting, hives, diarrhoea, runny nose, facial swelling, mouth tingling, burning sensation in the mouth and lips. In extreme case food allergy may cause anaphylaxis, which is a life-threatening condition that causes breathing difficulties, trouble swallowing and/or speaking, feeling dizzy and may even cause one to faint. Food allergies can be caused by many foods, such as milk, eggs, peanuts, tree nuts, fish, shellfish, or some fruits and vegetables and the allergies themselves are divided into 3 types, IgE-mediated food allergies, non-IgE-mediated allergies and mixed IfE and non-IgE mediated allergies(4). Food allergies are caused by the immune system. What happens is the immune system perceives certain proteins as a threat and answers back by triggering an allergic reaction.
- NHS, Food Intolerance, accessed on 13/05/21, available at: https://www.nhs.uk/conditions/food-intolerance/
- Cleveland Clinic, Food Problems: Is it an Allergy or Intolerance, accessed on 13/05/21, available at: https://my.clevelandclinic.org/health/diseases/10009-food-problems-is-it-an-allergy-or-intolerance
- National Institute of Allergy and Infectious Diseases, Food Allergy, accessed on 13/05/21, available at: https://www.niaid.nih.gov/diseases-conditions/food-allergy
- NHS, Food allergy, accessed on 13/05/21, available at: https://www.nhs.uk/conditions/food-allergy/