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What Is The Difference Between A Food Intolerance And A Food Allergy?

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Food intolerances and food allergies are often confused, even though the severity of symptoms produced by each condition varies significantly. Here is some information to help you understand the difference.

  • Food intolerances do not involve the immune system and reactions compared to food allergies are less severe.
  • Food allergies are immune-mediated responses, also known as anaphylaxis and can exhibit be life-threatening symptoms. 
  • Food intolerances are believed to affect up to 25 per cent of the population, whereas food allergies are far less common; although Australia has one of the highest prevalence rates in the world.  

Common symptoms of a food intolerance include bloating, irregular bowel habits, constipation/diarrhoea, nausea and stomach pains. Some people may also experience other symptoms such as migraines/headaches, hives/itchiness and wheezing or a runny nose. Symptoms can onset either immediately or many hours, even up to many days after consuming particular foods. These symptoms do not involve the immune system and are generally not life threatening; unlike food allergies, which may cause a whole body reaction known as anaphylaxis. 

Anaphylactic attacks can produce symptoms such as hives, swelling of the face, tongue and throat, plus difficulty breathing, vomiting and loss of consciousness. 

The increasing incidence of food allergies and intolerance is concerning. Currently there is no cure for food allergies and the only successful method to manage a food allergy or intolerance is to avoid the foods containing that allergen or food component. 

The actual causes are unknown and speculation goes back as far as to the environment in utero during pregnancy, including the mothers diet and exposure to allergens.  There is even lots of research now around the benefits of breast feeding for preventing food allergies/intolerances as well as the timing of food/solids introduction to babies, especially the timing of introductions of common food allergens. 

The most common food allergens include;

1.     crustaceans

2.     eggs

3.     fish

4.     milk

5.     peanuts

6.     soybeans

7.     tree nuts

8.     sesame seeds

9.     gluten/wheat


The most common food intolerances include:

·       Lactose – Commonly found in milk and dairy products.  The incidence of Lactose intolerance in Australia is thought to be around 10%.  Lactose intolerance results from a lack of the enzyme lactase needed to digest lactose. 

·       Fructose – In fructose malabsorption, the small bowel has difficulty in absorbing fructose, and as a result, the fructose moves through to the large intestine unabsorbed.  Fructose is found in various fruits/vegetables, wheat and honey.

·       FODMAPs – Along with Fructose, many people suffer from malabsorption of other carbohydrates grouped together by the term FODMAPs. FODMAPs include Fructose, Fructans, Galactans (Raffinose), Polyols (Sorbitol) and Lactose. Only fructose and lactose can be tested, the remaining FODMAPs will be identified as triggers during a dietary challenge conducted in consultation with a dietitian.

·       Food additives – Such as colours, preservatives and additives

·       Sulphites, Salicylates and Amines – These are natural food chemicals found in a huge variety of foods including herbs and spices, fruits and vegetables as well as wine and meat. 

The gold-standard test for diagnosing lactose and fructose intolerance is a Hydrogen (or Methane) Breath Test.  This test involves the ingestion of the substrate in a liquid form, then performing several breath tests over two to three hours to assess the production of hydrogen (or methane) from bacteria in the bowels.  Humans don’t naturally produce Hydrogen (or methane), therefore if levels increase significantly above baseline levels, then it can be assumed that food is being undigested and then fermented back bacteria in the gut. 

Other food intolerances can be diagnosed with the help of an experienced Accredited Practising Dietitian (APD) by using an elimination diet and then the re-introduction of foods over a period of 6-8 weeks as symptoms resolve. If you suspect you have a food intolerance, you can contact FOOD MAPPING for food intolerance testing (phone 03 9770 7189 or visit www.foodmapping.com.au). Once your test results are available, seek a referral from your GP to an Accredited Practicing Dietitian (APD) or go to the Dietitians Association of Australia website for a listing of all APDs (www.daa.asn.au).

What Is The Difference Between A Food Intolerance And A Food Allergy?
Kate Save:  Dietitian, Exercise Physiologist, Diabetes Educator and Personal Trainer
Accredited Practising Dietitian (APD), Dietitian, Nutritionist, Sports Dietitian, Sports Nutritionist