Diet and nutrition

What’s the difference between food allergy and food intolerance

01/03/2016 difference between food allergy and intolerance


Food allergy and food intolerance are often confused: symptoms of food intolerance sometimes resemble those of food allergy. Generally, the first difference between food allergy and food intolerance is that the second one doesn’t involve the immune system and doesn’t cause severe reaction known as anaphylaxis. 

Now we’re going to explain the key points of food allergy and food intolerance.

Allergy is an immune response

Food allergies are an overreaction of the body’s immune system to a protein. These proteins may be from foods, pollens, animal hair, house dust or mold. They are called allergens because the immune system has responded to a harmless substance as if it were toxic. The immune system makes specific IgE antibodies to “fight off” the allergens found in the foods. A specific IgE blood test can confirm this type of allergy correlate with clinical symptoms.


Symptoms of Food Allergy

Usually, food allergy reaction is immediate, from 12 to 24 hours after consuming the food and the symptoms can be life threatening. Common symptoms include:

  1. Itching and burning around the mouth
  2. Runny nose
  3. Vomiting and tummy pain
  4. Skin rash
  5. Hives and urticarial
  6. Anaphylaxis shock


In many serious cases, anaphylaxis shock is life threatening and needs medical attention. Within minutes of exposure to allergen, the person with an anaphylaxis shock can show these symptoms:

  • Difficult breathing
  • Swelling of the tongue
  • Difficulty talking
  • Wheeze and persistent cough
  • Persistent dizziness or collapse
  • Becoming pale and floppy

To prevent injury or death, a person with anaphylaxis shock requires an injection of adrenaline: people who are at risk of anaphylaxis are prescribed an adrenaline auto injector.


Common foods that cause allergies are:

  1. Eggs
  2. Fish and shellfish
  3. Groundnuts
  4. Milk
  5. Nuts from trees
  6. Peanuts
  7. Wheat
  8. Sesame


Food allergy is increasing

Allergies in general are increasing worldwide and food allergies have become more common, in particular peanut allergy in preschool children together with cow’s milk allergy.

Sometimes, people can tolerate a well cooked version of the food but will react to the food in its semi-cooked and raw state. For example, eggs in a cake are often well tolerated, but may cause reaction when they are boiled.

Food intolerance is a chemical reaction

Food intolerance can be a difficult concept to understand also by doctors. In general, we can say that food intolerance is a chemical reaction that some people have after eating or drinking some foods. So it’s not an immune response and not involve IgE antibodies. Food intolerance has been associated with asthma, chronic fatigue syndrome, upset stomach and irritable bowel syndrome.

Food intolerance reactions are usually related to the amount of the food consumed, but this amount varies for each person. Reactions are usually delayed and occurring several time after eating the offeding food.

The most common causes of food intolerance are:

  1. Absence of an enzyme needed to fully digest a food, such as the lactose intolerance
  2. Irritable bowel sydrome
  3. Food poisoning
  4. Sensitivity to food additives, such as suplhites added to processed foods
  5. Stress and Psycological factors
  6. Lifestyle with erratic food intake and poor nutritional intake or high fat diets
  7. Celiac disease: in this case we have some features of a true food allergy, because it involves the immune system, but symptoms are mostly gastrointestinal and people with celiac disease are not at risk of anaphylaxis like people with food allergy.


Symptoms of food intolerance

Symtoms of food intolerance can include:

  1. Nervousness and tremor
  2. Sweating
  3. Palpitations
  4. Headache
  5. Diarrhoea
  6. Burning sensations on the skin
  7. Breathing Problems
  8. Lethargy


The foods that tend to cause food intolerance include:

  • Dairy product, in particular cow’s milk and yoghurt
  • Chocolate
  • Eggs
  • Strawberry, citrus fruits and tomatoes
  • Wine
  • Beans
  • Gluten
  • Processed meats


Avoiding the food: how treat food intolerance

It is possible be intolerant to several different foods at the same time, in this case it’s very difficult to determine what kind of food is the real cause of the illness.  The duration of food intolerance is not defined, but after excluding the problematic foods the symptoms disappear and people can rentroduce the offeding food in some months. Obviously there are some exceptions, it’s the case of people who lack the enzymes needed to digest foods. For example in lactose intolerance the enzyme isn’t produce  in enough large amounts to break down the lactose (milk sugars). Other similar reaction is for chemical components produced naturally in foods such as caffeine or histamine in foods like strawberries, chocolate and ripe cheese.


Avoiding the food: how live with food allergy

In case of food allergy, the only thing to do is to avoid the problematic food. In that case, it’s very important to learn the terms used to describe these foods on labels. Here same examples:

  • Milk protein: milk, non-fat milk solids, caseinates, whey, lactose, cheese, yoghurt
  • Eggs: albumen, yolk, egg lecithin
  • Gluten: wheat, barley, rye, triticale, wheat bran, malt, oats, cornflour, oat bran
  • Soy: soybeans, hydrolysed vegetable protein, soy protein isolate, soy lecithin
  • Salicyclates: strawberry, tomatoes.


Keep a diary of all suspected food related reactions, with records, dates and labels, will help to identify which foods cause specific symptoms. In all case, intolerance or allergies, always read carefully the food labels and turn to a specialist doctor and a nutritionist.



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