Explaining the difference between allergy and intolerance

One of the greatest nutrition issues is that people start believing they have a food allergy or intolerance when they actually don’t. They stop eating specific nutrients and attribute every positive effect to that waiver. But commonly the positive effect is due to a higher awareness – what to eat, eating less, eating quality food. But when eliminating essential nutrients from your diet your nutrition becomes unbalanced and unhealthy.

Most likely in that context, you’ll hear about things like lactose-intolerance or gluten-sensitivity. Don’t get me wrong – allergies and intolerances exist and if you’re one of the few affected people it sucks. Also, I don’t want to give a doctor’s advice – if you are scared and in pain, go to your doctor immediately. I simply want to address people who were convinced of having allergies or intolerances by social media or newspapers.

Check the symptoms: allergy or intolerance?

Allergies and intolerances are triggered by compounds from you diet, but they express differently. This is due to the activated reaction pathway.

Allergy

is usually triggered by protein (e.g. from milk, eggs, fish, peanuts or soy). Therefore those are called allergenes. They cause a reaction of the immune system when entering the body, because they’re falsly considered as a threat. The immune system reaction can be either

  • (a) production of antibodies (especially Immunglobulin E/ IgE), which causes release of histamine and in the worst case a life-threatening anaphylaxis
  • (b) activation of different immune cells without antibody production, which causes inflammatory symptoms
  • mixtures of these types.

Allergies show similar symptoms shortly after consumption like itching, rash, wheezing, face-swelling or breathing problems, although the IgE-mediated form is the most severe one.

Intolerance

is also triggered by components of your food, which in contrast do not cause a reaction of the immune system and is in general not life-threatening. There are multiple causes for non-allergic food intolerances or sensitivities, e.g.

  • metabolic deficiency (lacking digestive enzymes)
  • gastrointestinal infections (toxins, viruses, bacteria)
  • disorders from anatomic abnormalities
  • biochemical transport defects
  • pharmacological/toxin-mediated reactions

However for some intolerances or sensitivities the underlying mechanism remain unclear (idiopathic). Symptoms are rather unspecific and sometimes hard to distinguish from stress symptoms. Typically an intolerance expresses as bloating, stomach pain, diarrhoea or skin irritation. The symptoms can occur several hours after consumption of a specific food.

Prevalence data – how likely is having a food allergy?

Allergy

The broad opinion is that food allergies are on the rise compared to the last decades. But accurate determination of food allergy prevalence is quite challenging. The gold standard (see How to diagnose; Oral food challenge) is resource intensive and therefore the availability of high quality data is low. Currently the majority of available data is based on self-reporting, which leads to an overestimation of prevalence by a factor three to four. Furthermore, the overall awareness and the improved diagnositc procedures contributed as well to the increased prevalence of allergies nowadays. Since allergies are not cureable and therefore a lifelong burden, it is most likely that the prevalence will increase further, although the number of newly diagnosed cases will stay the same (incidence). It’s just a matter of statistics (Read more about it in The Epidemiology of Food Allergy in the Global Context).

In conclusion it is widely accepted that food allergies affect approximately 2-5% of the population. Most common food allergies are shellfish, dairy and peanut.

Intolerance

Since it is difficult to properly diagnose intolerances and to distinguish it from sensitivities or general problems with digestion of certain foods, it is not easy to specify an actual prevalence. However, common sense is an average prevalance of 15-20% of the population.

Common intolerances are

  • lactose-intolerance
  • monosodium glutamate
  • caffein
  • alcohol
  • artificial sweteeners
  • histamine
  • toxins/ viruses/ bacteria
  • (gluten-intolerance or wheat-sensitivity)*

*Interestingly, a lot of people cut out wheat products from their diet, because they think they’re having a gluten-intolerance. It is tremendously hard to know whether symptoms are coming from gluten or another protein in wheat. In fact, only a few people actually have a diagnosed disease called coeliac disease (where it is essential to cut out gluten), but which is neither allergy nor intolerance, but an autoimmune condition, that affects less then 1% of the worlds population.

How to diagnose food allergy or intolerance

Allergy

Common tests for allergies are antibody-blood tests (e.g. for IgE) or skin prick tests (SPT), but they are not the most accurate methods. Especially the SPT does not establish a causative relationship between the intake of and the hypersensitive reaction to the suspect food. Therefore it can only be an estimation. Although it is a first hint, it is not proving the digestability of the suspect food. Surprisingly you can even tolerate digesting a certain food and still show a positive reaction in the SPT.

Still the gold standard is the Oral Food Challenge (OFC) where a small amount of the suspect food is given to the patient. The amount will be increased until a mild reaction – which is not harmful to the patient – is detectable.

Intolerance

Diagnosing food intolerances is fairly difficult. Except for common ones like lactose-intolerance, where you can perform a hydrogen breath test, most of them can not (yet) be tested in a scientifc manner. Still unconventional and to some extent misleading tests are quite abundant. Although they’ve been shown to be unreliable and inaccurate they’re still promoted for diagnosis. So be cautious about tests for food intolerances and rather contact you trusted doctor or dietitian for advice.

A treatment based on a misleading test can not only be ineffective, but also harmful for you.

What can you do?

#1 Relax and take a breath

Think about how likely it is that you are intolerant or even have an allergy. Furthermore, can you think of any other reason that might cause your uncomfort after having a meal? Are you stressed, ate to fast or too much? Was is too hot or cold, too salty or fatty? Did you sit down and ate consciously or just shoved something in in front of the TV?

Firstly, address your eating behaviours. Secondly, go to the food and symptoms diary.

#2 Food & symptoms diary

If you are quite certain that your symptoms are not caused by stress or your eating behaviour – maybe you already suspect a specific meal or nutrient – try a food & symptoms diary. It’ll provide you (and later your dietitian or doctor) with an objective list of everything you ate and symptoms you showed. Furthermore, try to describe everything as accurate and detailed as possible – date and time, amount and composition, symptoms and duration. Maybe you even solve the problem on your own, just through eating more diligently.

If not, thirdly – visit a dietitian, nutritionist, doctor or gastroenterologist.

#3 Trusted dietitian or doctor

I am not a doctor and I am not a professional dietitian. All I want to do is provide you with information and give you a direction and guidance. So in conclusion, if you are in constant pain and in any cases of doubt see a doctor! A doctor can determine correctly if you’re burdened with sensitivity, intolerance or an allergy. It is the best way to know for sure instead of guessing on your own or eliminating foods from your menu just in case.

Overview

  ALLERGY INTOLERANCE
target immune system digestive system
consequences can be life-threatening (anaphylaxis) uncomfortable, but less serious
symptoms itching, rash, wheezing, swelling of face (angiodema) bloating, stomach pain, diarrhoea, skin irritation
time quickliy after consumption few hours after consumption
cause antibody- or immune cell-mediatedenzymatic, pharmacologic, anatomic, infectious, idiopathic
examples nuts, fish, eggs, milk, soy, wheat lactose, fructose, histamine, caffeine
prevalence 2-5% 15-20%
References

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