Foods, food additives and chemicals are not common triggers for asthma – they affect less than five per cent of people with asthma. They rarely trigger asthma by themselves, but can trigger asthma either as part of a food allergy or an intolerance reaction.
An allergy is when the body’s immune system overreacts to a substance that is normally harmless to most people. These substances are also known as allergens. Being exposed to an allergen may cause irritation or swelling in areas of the body such as the nose, eyes, lungs, air passages and skin. A severe food allergy reaction is known as anaphylaxis and can be life-threatening.
Symptoms of food allergies
An allergic reaction to food may be mild, moderate or severe. Some of the symptoms may include:
- generalised skin rash (urticaria)
- itching, burning and swelling around the face and mouth.
Anaphylaxis is potentially life threatening
An anaphylactic reaction, or anaphylaxis, is an extreme allergic reaction that can be life threatening without prompt medical treatment. A life-saving injection of adrenaline, administered through an auto-injector, is required to treat anaphylaxis to prevent permanent injury or death.
The onset of symptoms can occur immediately (within two minutes to two hours) or steadily get worse over time.
Some of the symptoms of anaphylaxis include:
- persistent cough
- a strange taste in the mouth
- swelling of the tongue
- difficulty talking
- dizziness or collapsing
- noisy breathing
- difficulty breathing
High-risk foods that may cause allergies
Some of the foods that may cause an allergic reaction in susceptible people include:
- tree nuts
Food chemicals that may cause asthma
Intolerance to food chemicals is dose-related, which means the symptoms get worse as more of the chemical is ingested.
Some of the food chemicals that are known to trigger asthma in susceptible people include:
- sulphites – such as sulphur dioxide and sodium metabisulphite. These additives are often used in processed foods as preservatives. Common sources include wine, fruit juices, canned fish and dried fruit
- food colourings – such as the yellow food dye tartrazine. Food colourings very rarely trigger asthma attacks. Generally, if a person with asthma reacts to one food colouring, they should make sure to avoid eating any food colourings
- monosodium glutamate (MSG) – this is a naturally occurring chemical, frequently used as an additive to enhance flavour, particularly in savoury snack foods. Foods that contain high concentrations of MSG include stock cubes, gravy, soy sauce and packet soups. Hydrolysed vegetable protein is sometimes added to foods in place of MSG, and may trigger asthma in people who are sensitive to MSG
- salicylates – naturally occurring salicylates are also present in many foods, including instant coffee, soy sauce, tomato paste and sauce, beer and honey. The drug aspirin (acetylsalicylic acid) is also a salicylate. Other non-steroidal anti-inflammatory drugs (NSAIDs) may also trigger dangerous attacks in people who are sensitive to aspirin. Around five to 10 per cent of people with asthma are sensitive to salicylates.
Identifying trigger foods It is important to identify the foods or food chemicals that may cause problems for you. This must be done under strict medical supervision. Don’t try and diagnose the trigger foods yourself, because you may restrict your diet unnecessarily and this may be unhealthy. For example, some people with asthma avoid dairy products because they believe (incorrectly) that these foods cause an overproduction of mucus in the airways.
Your doctor or allergy specialist may conduct a blood test or skin prick test to determine your allergies.
Read the labels on food products
Some food additive numbers to remember include:
- sulphites – 220–228
- tartrazine – 102
- other food colourings – 107, 110, 122–129, 132, 133, 142, 151, 155
- monosodium glutamate – 620–625.
If you are looking for more information, you could check the Official Shopper’s Guide to Food Additives and Labels, which is available through libraries, major bookshops, supermarkets and newsagencies. Food Standards Australia New Zealand (FSANZ) also has a list of food additives and their numbers on their website.
No special asthma diet
Only a small percentage of people with asthma have food allergies or intolerances that trigger asthma flare ups.
It is important to remember that no foods either cause or prevent asthma. Like anyone else, people with asthma should eat a healthy, balanced diet that includes plenty of fresh and unprocessed foods. If you are concerned about your diet, consult with your doctor or dietitian.
Where to get help
This page has been produced in consultation with and approved by:
Asthma Foundation of Victoria
Content on this website is provided for education and information purposes only. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your doctor or other registered health professional. Content has been prepared for Victorian residents and wider Australian audiences, and was accurate at the time of publication. Readers should note that, over time, currency and completeness of the information may change. All users are urged to always seek advice from a registered health care professional for diagnosis and answers to their medical questions.