FAQ: What’s The Difference Between A Food Intolerance And A True Allergy

“Are you really allergic? Or are you just intolerant?”

It’s a question often asked of a food intolerant person. It can often be disparaging, perhaps not intended to make to the sufferer defensive, but disheartening none-the-less. Oftentimes, people with food intolerances are treated as fussy eaters with no real problem. But the truth is that food intolerances are very much a physiological reality.

There is a difference between a food allergy and an intolerance. Basically, food intolerances are chemical reactions, while food allergies are immune responses [1]. However, regardless of whether or not you have a ‘true’ allergy, you’ll have a very real reaction. Pain, discomfort, and other serious symptoms can be the repercussions of both allergy and intolerance.

Never-the-less, it is helpful for patients to understand the difference between the two issues – if for no other reason than that it validates their issue, and gives them a way to respond to those who would discount it as some form of a lesser illness.

The difference all comes down to immunoglobulins – the antibodies that exist in the serum cells of our immune systems. There are five, but three of these immunoglobulins are responsible for reactions to food or other substances. Two of the, IgG and IgA can be very similar. They both affect bodily fluids, with IgA affecting tears, blood and saliva as well as protecting areas that are exposed to foreign substances. IgG antibodies are the most common of the immunoglobulins, making up 75%-80% of all immunoglobulins. They are present in all body fluids.
The third, IgE is quite different.

“IgE antibodies are found in the lungs, skin, and mucous membranes. They cause the body to react against foreign substances such as pollen, fungus spores, and animal dander. They are involved in allergic reactions to milk, some medicines, and some poisons.[2]”

Common testing for ‘true’ allergies involves skin prick testing. This can occur because with allergies, the reaction is most often instantaneous [3]. It occurs in the seconds and minutes after exposure to the allergen. True allergies often manifest in the following ways:

  • Tingling, itching or hives
  • Swelling of the lips, tongue, throat or other parts of the body
  • Wheezing, nasal congestion or trouble breathing
  • Abdominal pan, diarrhea, nausea or vomiting
  • Dizziness, lightheadedness or fainting
  • Anaphylaxis, in which the patient sufferers a severe allergic reaction requiring urgent medical attention [1].

Regardless of whether the patient has been exposed to a large or small amount of the allergen, the result will be the same. Even tiny exposures will reap the same result with allergies.
This is where food intolerances are different: they are often dose dependent, occurring only when you consume the allergen often or in high doses. Another point of distinction is that food intolerances take time to brew. You could consume a food and not feel the results until hours or even days later. This means a skin prick test cannot be used to determine the intolerance.

Commonly, elimination diets are used to determine them. These have to be spaced out and slow, as it can be very easy to confuse reactive foods should you reintroduce too many reactive foods in close succession.

Symptoms of food intolerances include:

  • Sweating and palpitations
  • Diarrhea and stomach upsets
  • Rapid breathing and asthma
  • Migraines and headaches
  • Tightness in the face and chest, or burning sensations on the skin

In fact, food intolerances may look a lot like allergic reactions. Hence, they can be quite serious. The difference between the food intolerance and the food allergy lies simply in the immunoglobulin – with one being instantaneous, and one being long term and dose dependent.

In recent years, a blood profile test has become available through some functional pathology companies. The IgG Blood Profile test helps discover food intolerances that would previously only have been discovered through elimination diets that may take months. We can finally test for IgG (food intolerances) as easily as we can test for IgE reactions or true allergies.
Good news for sufferers, indeed.


[1] http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/food_allergy_and_intolerance

[2] http://www.webmd.com/a-to-z-guides/immunoglobulins

[3] Staff Writer, 2014, ‘Food Reactions: Clinical Information for Professionals,’ Rocky Mountain Analytical, USA

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