10 Common Food Intolerances - When you Should Take a Food Intolerance Test

General Medical

Tammy George

Bowls of food on a table that are considered to be the cause of common intolerances and allergies.

Food intolerances can make life challenging for many Australians. While food intolerances aren’t usually life threatening like allergies, they can make daily life unpleasant if you’re not sure what’s causing your symptoms and when the next bout will hit.

10 Common Food Intolerances

Any food type has the potential to cause an intolerance in one person, but there are individual foods and food groups that are likely to cause the most intolerances amongst the population.

The most common ones are:


#1 Milk 

Some people are lactose intolerant. They aren’t able to digest the sugar (lactose) in milk due to insufficient amounts of the gut enzyme lactase, found in the small intestine. Most lactose intolerant people can tolerate eating cheese and small amounts of yoghurt. There is often a genetic link in lactose intolerant people.

#2 Gluten 

Another common intolerance is gluten, which is caused by a protein found in wheat, barley and rye. Celiac disease is the most severe form of gluten intolerance. The autoimmune disease affects about 1% of the population and can cause  damage to the digestive system

It is thought that up to 13% of the population may have non-celiac gluten sensitivity, a mild form of gluten intolerance that can cause symptoms.

#3 Caffeine

Drinking caffeinated coffee, tea or cool drinks can cause reactions in anyone who consumes high quantities - more than 400 mg of caffeine in one day. However, someone who is sensitive to caffeine will experience negative reactions after consuming one cup of coffee.

A barista making a cup of coffee - caffeine is a common food intolerance for many.

#4 Salicylates 

Salicylates are a natural ingredient found in many fruits, vegetables and spices. Plants produce salicylate to protect themselves against insects, fungus and disease. Salicylates are also synthetically produced for use in aspirin, toothpaste and food preservatives. People with a sensitivity to salicylates experience side effects because their body can’t properly metabolise and excrete them from their bodies. Adults with asthma are most likely to suffer from a salicylates intolerance. 

#5 Wheat

A wheat intolerance isn’t the same as a gluten intolerance. It is possible for a person to be wheat intolerant but not gluten intolerant, so they can still enjoy other grains such as barley and rye. Wheat can appear in bread and a range of other food products, such as salad dressings, processed meats, crackers, cereals, pasta and sauces.

#6 Egg

Many people struggle to digest the proteins in a whole egg, egg white or yolk and suffer from an egg intolerance. Some people are intolerant to just the white, while for others it’s the yolk. Some people aren’t intolerant to chicken eggs but can’t eat the eggs of quails, ducks or geese. Egg replacements can be used for baking and to ensure there are no nutrient deficiencies after eliminating eggs from the diet.

Scrambled eggs on toast - egg is considered a common food intolerance.

#7 Amines 

Amines including tyramine, serotonin and histamine are naturally present in pineapples, bananas, baked meats, vegetables, red wine, avocados, chocolate, matured cheese and citrus fruits. They can cause small blood vessels to expand, which can induce flushing and nasal congestion.


FODMAP stands for “fermentable oligo-, di-, mono-saccharides and polyols”. A FODMAP intolerance occurs when the body struggles to digest certain carbohydrates that are commonly found in wheat and beans. Instead of being absorbed into the bloodstream, the short-chain carbs reach the far end of the intestine, where the gut bacteria resides causing digestive issues.

#9 Sulfites

Sulfites are used as preservatives in drinks, foods and medications, but there are low levels of sulfites found naturally in many foods. Some of the most common sources of sulfites are beer, wine, biscuits, pies, dried fruit, jam and jelly.

#10 Fructose  

Fructose is fruit sugar found in many fruits, honey, some vegetables and many processed foods that contain added sugar. Fructose malabsorption occurs when the cells on the surface of the intestines can’t break down fructose efficiently. Cells in the intestines are responsible for ensuring fructose is directed to where it needs to go, but if there is a deficiency, fructose can build up in the large intestines.

Food Intolerance Symptoms

Symptoms of food intolerances vary from mild to extreme. Most people suffer from digestive related symptoms such as:

  • Bloating and excessive gas.

  • Stomach pain.

  • Diarrhea.

  • Constipation.

Other symptoms include:

  • Headache or migraine.

  • A runny or stuffy nose.

  • Flushing.

  • Tiredness.

  • Mouth ulcers.

A woman sitting on the edge of her bed holding her stomach in pain due to a food intolerance.

Types of Food Intolerances

According to the Australasian Society of Clinical Immunology and Allergy, there are four types of food intolerances

  • Metabolic conditions such as lactose intolerance (enzyme deficiency) and carbohydrate malabsorption (including fructose).

  • Pharmacologic (chemical sensitivity) reactions to foods containing caffeine, monosodium glutamate (MSG) and other naturally occurring food chemicals (salicylates and amines).

  • Toxic reactions such as food poisoning and scombroid fish toxin.

  • Adverse reactions to artificial preservatives such as sulfites and benzoates.

Food Intolerance vs Food Allergy

Many people make the mistake of calling their food intolerance a food allergy. However, the two are quite different. A food intolerance impacts the digestive system while a food allergy causes an immune response. An allergic reaction can be caused by the tiniest portion or even the odour of a food. An intolerance usually requires a much greater volume of food to be ingested in order to cause any symptoms. Food intolerances don’t result in an anaphylaxis reaction which can be life threatening like food allergies. Sulphite and benzoate reactions are the exceptions to this rule.

A woman experiencing an allergic reaction to food and using an epipen.

Diagnosis of Food Intolerances and Allergies

If you suspect that you may have a food intolerance, see your GP. They will most likely take your medical history, discuss the signs and symptoms you’ve noticed and decide whether diet is the main cause.

Your doctor may refer you for blood tests and/or a skin prick test to diagnose a food allergy if it’s possible that an allergy is the cause of the symptoms. A skin prick or scratch test involves exposing the skin to the suspected allergy-causing substances (allergens), then observing the skin for any signs of an allergic reaction.

While the test can be used for food allergies, it’s most effective for diagnosing allergies to airborne substances, such as pollen, pet dander and dust mites. Swelling, itching and redness at the site of the test are signs of an allergic reaction. Prescription and over-the-counter medications can reduce the effect of a skin test, so let your doctor know what you’re taking in case you need to stop taking it in advance of the test. Diagnosing allergies can be complex and other tests may be required.

A doctor performing a skin prick test on a patient’s arm to diagnose a food allergy.

Food Diary

Keeping a food diary is one way of diagnosing a food intolerance. The diary documents the foods that were eaten, any symptoms that appeared, and their timing. The information can help people work out which foods are causing adverse reactions. Some symptoms of food intolerances occur soon after consumption while others can take up to 72 hours to appear.

Elimination Diet

An elimination diet or exclusion test is an accurate way of finding the foods that may be causing an intolerance. It involves removing certain foods that are most likely to be causing symptoms and reintroducing them one at a time, while you look for symptoms that show a reaction.

A man unloading fresh groceries as he starts an elimination diet to determine his food intolerances.

At the beginning of the diet, make a note of your symptoms by considering all parts of your body including:

  • Energy levels.

  • How well you sleep.

  • Whether or not you experience an afternoon slump.

  • Digestive symptoms such as bloating, gas, diarrhea, or constipation.

  • Usual bowel function.

  • Any skin rashes, hives, breakouts, etc.

  • Whether or not your head feels “fuzzy”.

The elimination phase usually lasts 2-3 weeks. Common eliminated foods include nuts, corn, soy, dairy, citrus fruits, wheat, foods containing gluten, eggs and seafood. During the reintroduction phase over the next 2-3 weeks, eliminated foods are slowly brought back into the diet while monitoring for symptoms. If there are no symptoms, you can assume these foods are fine to continue to eat. Once a food is identified as causing unpleasant symptoms, it can be eliminated from the diet.

If there are no symptoms during the 5-6 week test, the diet continues back at the elimination phase with a new group of foods to test. Eliminating too many food groups may cause nutrient deficiency, so it’s best to speak to your doctor or a dietician before conducting the elimination diet yourself.

The elimination diet can be used to diagnose a sensitive gut, food intolerance or food allergy. However, people with suspected food allergies shouldn’t follow an elimination diet unless it’s under the supervision of their doctor.

At-Home Food Sensitivity Tests

There are tests on the market that check how your immune system responds to different types of foods. The food sensitivity tests can help you quickly discover foods that trigger adverse symptoms such as gas and bloating. Some of these tests are reliable, but there are differences in the foods they test and the support the company provides.

Food intolerances can change regularly. Some people will suffer from an intolerance for a year or two then never experience it again, while other people will have a food intolerance for life. If you suspect that you’re suffering from a food intolerance, speak to your GP.

Tammy George

Please note: Tammy's blog is general advice only. For further information on this topic please consult your healthcare professional.

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