Give this to your GP about food intolerance!

Members of our 18,000 strong Food Intolerance Network frequently complain about the lack of recognition of food intolerance.

“We did the rounds of GPs, paediatricians, psychologists, social workers, OTs and child health nurses, and all the interventions and treatments helped a little, but nothing led to any significant improvement.  Not once was diet mentioned beyond ‘does he eat well?’” – Ursula in [1341] and see this facebook thread Rants about seeing Health Professionals [1298]

The trouble is that GPs are not trained in diet and its effects and they are often reluctant to accept that such a wide and often bewildering range of symptoms may have a single cause.
Most importantly, they do not know that there is a reliable way to scientifically diagnose food intolerances.

The article below was prepared for the journal that most GPs see, but they chose not to publish it. You are welcome to pass it to your GP directly and engage them in the issue.

Download and print (4 pages) to give to your GP please.  Here is the content of the printout:


Food intolerance rarely diagnosed by GPs        FINletterhead

Members of the 18,000 member Food Intolerance Network frequently report that their food issues were not diagnosed or taken seriously by general practitioners. Comments such as the following are all too common.

“In 23 years, not a single doctor ever once asked if my condition might be caused by the food that I eat “– Mark from story [524]

Such attitudes drive people to alternative medicine, which might work although not for the reasons given, but in the process the practice of medicine might be brought into disrepute.

The main reason seems to be that doctors are not familiar with food intolerance. It is not part of their training and they do not know that there is a reliable way to scientifically diagnose food intolerances. This article attempts to briefly address these issues.


There are no scientifically proven laboratory tests for food intolerance

The scientifically proven way to diagnose food intolerances is through the use of an elimination diet with challenges

Patients who would like to investigate diet can be referred to dietitians who regularly undertake the RPAH elimination and challenge process.

What is food intolerance?

Food intolerance can be clearly distinguished from food allergy. Food allergy is an uncommon, quick immune system reaction, usually to proteins in food. Food intolerance is more common, and is usually a slow pharmacological reaction, like the side effects of a drug, to a specific chemical or range of chemicals in food. Both children and adults can be affected but the prevalence is unknown.

Food intolerance symptoms are protean, as seen in Box 1, with a range of mixed and variable expression.

·         irritability, restlessness, difficulty falling asleep

·         mood swings, anxiety, depression, panic attacks

·         inattention, difficulty concentrating or debilitating fatigue

·         speech delay, learning difficulties

·         eczema, urticaria and other itchy skin rashes; angioedema or swelling of the lips etc often associated with rashes

·         reflux, colic, stomach aches, bloating, and other irritable bowel symptoms including constipation and/or diarrhoea, sneaky poos, sticky poos, bedwetting

·         headaches or migraines

·         frequent colds, flu, bronchitis, tonsillitis, sinusitis; stuffy or runny nose, constant throat clearing, cough or asthma·   

Box 1 Some symptoms of food intolerance

Conceptually, Figure 1 shows how a range of food sources of amines, which have known pharmacological effects, build up over time until a symptom threshold is reached. Unfortunately, it is usually the last food eaten that gets the blame, but that is not how food intolerance works. In this case, it would take elimination or reduction of all food and medication sources of amines over a period before symptoms would abate.

Figure 1 The cumulative and delayed nature of food intolerance (from Friendly Food, Murdoch Books 2004 ISBN 174045376X with acknowledgement to the Royal Prince Alfred Hospital Allergy Unit)

How can food intolerance be diagnosed?

It takes specialised knowledge to understand that all of the foods shown in Figure 1 contain, among other chemicals, natural biogenic amines. Fortunately, this clinical knowledge has been developed in the Royal Prince Alfred Hospital Allergy Unit Elimination Diet over 30 years.

The RPAH Elimination Diet works by avoiding a limited range of artificial and natural food chemicals over a three to six week period until, if food is in fact responsible, a stable baseline of symptom remission is obtained. This process is frequently accompanied by withdrawal symptoms, often a worsening of presenting symptoms, which itself provides evidence that food chemicals that were causing the symptoms. Systematic challenges over succeeding weeks then establish which food chemicals are responsible for the symptoms and dietary management within tolerance guidelines is implemented.

Australia is fortunate in that there are now trained dietitians who regularly undertake the elimination and challenge process described. Because it can be complicated for families, an experienced and supportive dietitian is necessary for success.

The Food Intolerance Network also provides free information and support for individuals and families through this process.

What are typical causes of food intolerance?

Most people with food intolerance react to between 3 and 6 food chemicals and effects are related to dose. Overall, the main culprits are a limited range of food additives and the natural food chemicals called salicylates, found in most fruit and some vegetables, as shown in Box 2. However everyone is different which is why the elimination diet and challenge protocol is required for scientific diagnosis. Surprisingly, other symptoms show a similar pattern.

Symptoms may emerge or change with age, stage of life, stress and illness. Food intolerance can be triggered or even caused by some medications.

75% react to natural food chemicals in most fruit and some vegetables called salicylates

65% react to preservatives such as sorbates, benzoates, sulphites, nitrates and propionates

55% react to some artificial colours and a natural colour

40% react to MSG and other flavour enhancers, natural glutamates

40% react to synthetic antioxidants such as BHA 320

40% react to natural food chemicals called amines

20% react to dairy foods

<1% react to gluten (figures are higher for other symptoms, up to 20% for irritable bowel)

Box 2 Approximate percentage of overactive children likely to react to each challenge following the RPAH Elimination Diet (adapted from Loblay RH, Swain AR. Food Intolerance. In: Recent Advances in Clinical Nutrition' Vol 2, 1986. Libbey, London. Eds: Wahlqvist ML and Truswell AS, pp169-177)


An increasing number of general practitioners are recognising food intolerance:

“For the last 15 years I have known of intolerances … I have the book "Friendly Food” and  have tried half half-heartedly to follow the diet but never with help … A recent doctor’s visit introduced me to your website. It is wonderful. I finally feel that I am not the only one”- Ann from story [1482]

Some of these are affected themselves:

“I'm a 40 year old physician who has a severe reaction to consuming annatto (natural colour 160b). If I eat any significant amount, I have the onset of severe vomiting and diarrhea roughly 12 hours later, which then persists for 12-24 hours. I don't have any classic "type I hypersensitivity" symptoms such as hives, just a severe delayed gastrointestinal symptoms ….” – from story [984]

And some have observed problems themselves:

“… symptoms in a boy aged 4 years old onwards … 160b annatto, high salicylates, glutamates and MSG - observed behaviour: defiance, prolonged tantrums, aggressive (out of character), poor concentration, irritable, difficulty settling at night for up to one week.” – Helen GP from story [1334] 

Patients who would like to investigate diet can be referred to dietitians who regularly undertake the RPAH elimination and challenge process.

Prepared by Dr Howard Dengate for the Food Intolerance Network, updated March 2022


References and more information

The development of the RPAH Allergy Unit elimination diet and challenges

Distinguishing food allergy and intolerance

Support and information for food intolerance

Recommended dietitians


Please download above article and print (4 pages) to give to your GP



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