What is Food Allergy? What Is Food Intolerance?

Many people mave food sensitivities. These are often relatively unnoticeable; perhaps causing little more than a  slight increase in digestive problems (eg. more gas, change in hardness of your stool). A slightly upset stomach may be thought to be a mild infection, but may be actually caused by a food sensitivity. Problems are commonly caused by excess sugars, over refined foods, gluten, wheat and dairy products; but can be caused by almost anything; and everyone is different. One person may be affected by coconut while hundreds of others are not; and another may be affected by one type of vegetable or fruit, and unaffected by most others.
Testing (eg. hair testing) is used by some medical practitioners to determine food sensitivities; and when tests are done, they will more often than not, turn up something that is a problem.

Food allergy

A food allergy is caused by an immune reaction to certain foods (e.g. nuts, eggs and shellfish). Symptoms include the development of skin rashes or hives, swollen tongue and lips, vomiting, wheezing, nausea diarrhea and difficulty breathing. Symptoms may occur rapidly (within 30 minutes) and be very severe. Individuals who have severe allergic reactions to foods need to be especially cautious because a food allergy can trigger potentially life-threatening anaphylactic shock. This is characterized by difficulty breathing and a dangerous drop in blood pressure.

Food intolerance

Food intolerance occurs when nerve endings are irritated by food chemicals. Be aware that this can be caused by both natural foods and artificial foods. Food intolerances are more common than food allergies and can affect babies (through breast milk), children and adults. Food intolerance can occur due to natural sensitivities in the digestive system or after a disruption to the system such as infections, dietary changes and stress; however it can also be an inherited condition. Often babies and children are more sensitive to food chemicals due to an immature digestive system.


The most important thing to understand about food intolerance is that it can be caused by a very wide range of food chemicals. This is very different from a protein allergy where the allergic reaction will only be triggered by that one type of food. As you can imagine trying to find the food intolerance culprits take quite a bit detective work.

All food is made up of chemicals, over long periods of time society has figured out what we can eat and most of us will tolerate these foods. What may be perfectly healthy for one person, may cause food intolerance in another. This is important to know as many ‘healthy’ foods contain food chemicals which are as problematic as artificial chemicals often used as additives. Patients, who react to natural foods, will usually react to artificial additives as well.


The next important point is that symptoms can vary widely, both in the type of reaction and in the amount of time taken for a reaction to occur. The latter part here will often depend upon the degree of sensitivity to a particular food. A patient may be able to tolerate small amounts of a food chemical, but when too much is consumed or it is consumed too frequently the patient will build up to a reaction as the food chemicals they cannot tolerate build up in their body.


Some of the most frequently occurring symptoms include hives (itchy red lumps that look like small insect bites), swellings, headaches, sinus, behavioral issues such as irritation, grumpiness, agitation, ADHD like symptoms in children (and may also include anti-social and aggressive behavior), general aches and pains or flu like symptoms, moodiness or feeling run down. Note that sometimes hives are just the tip of the iceberg. The reaction may be mainly subcutaneous (under the skin) so it is not visible. Breast fed babies may react to food chemicals in the mother’s milk. Symptoms of food intolerance can come and go and change throughout life.


Diagnosis of food allergy or intolerance:

  • Food allergies: IgE antibodies are detected using blood tests or skin prick tests. This does not assist with the detection of food intolerance.
  • Food intolerance: to properly diagnose and detect problematic foods, a strict elimination diet needs to be followed for 3 or 4 weeks. During the elimination diet the first week can be very challenging and the patient is likely to have symptoms and feel unwell. This usually clears up after the first week. When and if the symptoms disappear, you may then do challenges to find out which food chemicals the patient is intolerant of. Challenges are either by eating very specific groups of food (ie: those containing salicylates, amines, glutamates, dairy and or gluten) or by a double blind trial with capsules that contain the food chemicals. Note that food intolerance cannot be picked up by a blood test.


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