food allergy
Blog,  Nutrition

Food allergy, intolerance and preference

Do you know what is the difference between a food allergy, a food intolerance and a food preference? Why would you care? Well, if you work in an industry that involves serving or selling food to people (food manufacturer, restaurant, cafe, pub, bar, hospital, aged care facility, school, airline, catering company, hotel, bed & breakfast, food truck, etc.), you should.

Food Allergy

Allergy is an immune reaction to substances (allergens), which are usually harmless. The immune system reacts by producing antibodies.

The most common triggers are proteins in the following foods:

  • Peanut
  • Tree nuts
  • Milk
  • Eggs
  • Sesame
  • Fish
  • Shellfish
  • Soy
  • Wheat
  • Lupin

Allergic reactions can include hives, swelling of lips/eyes/face, abdominal pain, vomiting, wheeze. Reactions in infants include: colic, reflux, eczema, chronic diarrhoea and failure to thrive.

The most severe reaction is anaphylaxis, which can lead to death (although it’s not common in Australia and New Zealand). Anaphylaxis can be prevented by immediate administration of adrenaline (e.g. Epipen).

The current prevalence of food allergy is (1):

  • 10% of children up to 1 year old
  • 4-8% of children up to 5 years
  • 2% adults

Food allergies are on the rise and there are several hypotheses of why this is the case. However, the jury is still out.

Most food allergies in children are not severe and can be outgrown. Allergies to peanuts, tree nuts, seeds and shellfish are less likely to be outgrown.

Food allergies can be diagnosed by skin prick test or blood test and/or temporary elimination diet with food/capsule challenges under medical supervision.

Unproven and inappropriate methods that claim to test for allergy or intolerance include IgG testing to foods, cytotoxic food testing, kinesiology, Vega testing, electrodermal testing, pulse testing, reflexology and hair analysis.

Coeliac Disease

Coeliac Disease (CD) is not an allergy, but a condition that involves an immune response (hypersensitivity) to gluten, a protein present in wheat, rye, barley and oats. In people with CD, ingestion of gluten causes damage to the small intestine.

CD can begin at any age. Symptoms include but are not limited to: nutrient malabsorption, diarrhoea, abdominal cramps, bloating, nausea and vomiting. Non-digestive symptoms can include dermatitis, mouth ulcers, depression, brain fog, headaches, infertility, etc.

The estimated prevalence of CD in Australia is 1 in 70 people, with 4 out of 5 remaining undiagnosed (2).

Diagnosis is made using the following steps:

  1. Blood screening to assess antibodies and/or genetic markers
  2. Small bowel biopsy to confirm damage. Note that this has to be done after a period of gluten consumption. If your doctor tries to test you for CD even though you have told them you are not eating gluten, run the other way.
  3. Repeat biopsy after a gluten-free period to confirm recovery

The only treatment for CD is management through a gluten-free diet.

Food intolerance

Food intolerance does not involve the immune system, but it’s caused by the irritation of nerve endings.

The trigger is a build-up of natural or artificial chemicals in food, such as:

  • Glutamates (MSG, Camembert cheese, Parmesan cheese, tomatoes, soy sauce, mushrooms)
  • Amines (pineapples, bananas, baked meat, vegetables, red wine, wood-matured white wine, avocados, chocolate, citrus fruits, mature cheese)
  • Salicylates (herbs, spices, fruits, vegetables, aspirin)
  • Additives (natural and artificial colours, sulphites)

The most common symptoms are: hives, swelling, stomach & bowel irritation, headaches, tiredness and behaviour changes (moodiness, irritability, restlessness). Intolerance to food does not typically cause severe allergic reactions such as anaphylaxis.

Because food intolerance does not show on allergy testing, diagnosis is made by temporary elimination diet with subsequent food or capsule challenges. As with food allergy, unorthodox tests can be misleading (3).

Management is done through dietary modification; i.e. including foods with problematic chemicals below each person’s tolerance threshold.

Prevalence of food intolerance is not known but statistics of food avoidance can give a hint. The graph below shows the proportion of people who reported avoiding particular foods due to allergy or intolerance in the Australian Health Survey 2011-12 (4).

Food preferences

These are avoidance of certain food or food groups for a wide array of reasons, from taste to religion. Diets that cater to food preferences include: vegan, vegetarian, pescatarian, kosher, halal, paleo, keto, low-carb, etc. Note that there can be an overlap between food preferences and intolerances (or even allergies), for example one can choose to follow a paleo diet because they are intolerant to gluten and dairy.

The following graphs show a comparison of people who reported avoiding foods due to allergy/intolerance vs cultural, religious or ethical reasons (4).

The graph below shows the foods avoided for cultural, religious or ethical reasons (4).

What to do

The degree of avoidance of certain foods will depend on the type and severity of the adverse reaction. People with food allergies or Coeliac Disease typically need to be more vigilant than people with food intolerance.

Below are a few tips that might make life easier when food preparation is out of your control:

  • Read labels. The major allergens must be declared in all packaged foods.
  • Check menus before eating out and ask the restaurant if the menu is not descriptive enough.
  • Indicate dietary requirements when registering for work functions, conferences, etc.
  • Most airlines and even interstate trains offer special meals. If you’re not sure or your airfare does not include a meal, bring food that is safe for you or fast.
  • Bring backup snacks to parties, picnics, etc.
  • Be honest. There are people who suggest claiming allergies so that restaurants, hospitals, etc. are willing to cater to what is not a health-threatening intolerance or preference. In my opinion, it is better to be upfront and clear with your requests. This also can prevent businesses from dismissing actual allergies just because “everyone claims to have an allergy”.

Further to the above, if you are avoiding particular foods or food groups, please make sure you are meeting your nutritional needs. Also, remember some adverse reactions might be exacerbated by underlying issues (e.g. gut health) and some might change over time. Work with a dietitian in case you need help.


  1. Australasian Society of Clinical Immunology and Allergy. Food Allergy [Available from:
  2. Coeliac Australia. Coeliac Disease [Available from:
  3. Australasian Society of Clinical Immunology and Allergy. Food Intolerance [Available from:
  4. Australian Bureau of Statistics 2004, Australian Health Survey: Nutrition First Results – Foods and Nutrients, 2011-12, ‘Table 14: Food avoidance due to allergies or intolerances then type of food avoidance for cultural, religious or ethical reasons’, data cube: Excel spreadsheet, cat. no. 6261.0.55.00, viewed 30 September 2018

[Photo by Tom Hermans on Unsplash]

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