Food Intolerance: Causes, Symptoms, Treatment

Food intolerances differ from food allergies in that they involve the digestive system rather than the immune system. While food allergies can be life threatening, causing anaphylaxis, food intolerances do not cause such extreme reactions. However, if food intolerances are not properly managed, the symptoms may adversely affect general health and wellbeing (Australasian Society of Clinical Immunology and Allergy (ASCIA), 2019).

Food intolerance can be caused by compounds that are found naturally in foods, or by compounds that are added to foods such as flavour enhancers or colourants. The only way to find the compound responsible for the symptoms is by an elimination diet followed by a challenge procedure closely supervised by a health professional. Different people will tolerate different amounts of the substance, and larger amounts may cause stronger symptoms (Dietitians Australia, 2020).

Common food intolerances

• Lactose intolerance: caused by an enzyme deficiency (lactase), can cause bloating, flatulence, stomach upset and diarrhoea
• Monosodium glutamate (MSG): found naturally in foods such as camembert cheese, parmesan cheese, tomato, soy sauce and mushrooms, also isolated and used as a food additive to enhance flavour
• Vasoactive amines: such as tyramine, serotonin, and histamine, commonly trigger headaches or migraines. Naturally found in pineapple, banana, some vegetables, red wine, avocado, chocolate, citrus fruit, and mature cheese
• Salicylates: a natural aspirin like compound found in a variety of herbs, spices, fruits, and vegetables
• Toxins: found in contaminated food and can cause severe symptoms (food poisoning)
• Irritants: caffeine and curry are gut irritants and may trigger indigestion


• Bloating
• Migraines
• Headaches
• Stomach-ache
• Flatulence/gas
• Diarrhoea
• Recurrent mouth ulcers
• Hives
• Cough
• Runny nose
• Feeling generally unwell
• Irritable bowel


As mentioned above, the only way to diagnose a food intolerance and find the compound responsible is by an elimination diet followed by a challenge procedure closely supervised by a health professional.


Once a diagnosis has been made, a clinical history may help identify the role of diet and any other factors that may make your symptoms worse, for example, exercise. The only way to treat a food intolerance is to either avoid the foods that cause symptoms or to eat them less often and in smaller amounts. In some cases, reintroduction can be trialled under the supervision of your health care professional, such as with lactose intolerance.

For more information, or to book in with a General Practitioner or Dietitian, please call reception.

The information in this article has been adapted from:

Australasian Society of Clinical Immunology and Allergy (ASCIA). (2019). Food Intolerance. Retrieved from Australiasian Society of Clinical Immunology and Allergy (ASCIA):
Dietitians Australia. (2020). Understand food intolerance and sensitivity. Retrieved from Dietitians Australia:

This article was written by April Stevens BSc. MD student. 

15th December 2020.