Food and asthma

The good news is food is not a common trigger for people with asthma. Around 6-8 % of children with asthma and 2% of adults with asthma have a problem with certain foods triggering their asthma symptoms.  

Food can trigger asthma symptoms because:

• you are allergic to certain foods and the allergic reaction triggers your asthma symptom (a food allergy)
• you are sensitive to certain foods which trigger your asthma symptoms (a food intolerance). 

Food allergies

A food allergy is when your body’s immune system reacts to certain types of food. You have a slightly higher chance of having a food allergy if you have asthma.

You can be allergic to any type of food, but the most common food allergies are egg, cow’s milk, wheat, peanuts, tree nuts, soya, and shellfish.

An allergic reaction to food can affect any part of the body, including the airways. This can bring on asthma symptoms in some people with a food allergy.  

If you have a food allergy, the best way to prevent an allergic reaction is to completely avoid the food you are allergic to. Allergic reactions to food can happen very quickly and a severe allergic reaction (anaphylaxis) can be life threatening.  

An anaphylactic reaction and an asthma attack can look similar. If you have both a food allergy and asthma, and are in any doubt about your symptoms, use your adrenaline auto-injector (such as an EpiPen) and your reliever inhaler straight away and call 999.

Find out more about different food allergies on the Allergy UK website. 

Food intolerance

A food intolerance is when you are sensitive to certain foods and have a bad reaction. A food intolerance is different from a food allergy. This is because food intolerances are not caused by your immune system.

You can be sensitive to any kind of food, but the most common food intolerances are lactose, gluten, food additives, and food chemicals. Symptoms usually affect the gut, skin and respiratory system.  

More research is needed to understand the link between food intolerances and asthma symptoms. However, it could be that some of the chemicals and ingredients in food trigger asthma symptoms. Substances found in alcohol can also trigger asthma symptoms for some people.

Find out more about food intolerances on the Allergy UK website. 

Your GP can refer you to food and nutrition specialist (dietician) to do some tests to help you work out if you are allergic or sensitive to certain foods. Test may include:

• a skin prick test
• blood tests
• a special diet where you avoid certain foods to see if your symptoms improve. Don’t cut out foods without speaking to your GP, nurse, or a food and nutrition specialist (dietician) first.
• a breath test to see if you are lactose intolerant.

Your GP or nurse may ask you to keep a food and symptom diary to identify foods you are sensitive to that don’t show up in allergy tests. Allergy UK has a free food and symptom diary you can fill in and review with your GP or nurse.  

Your GP or nurse can also look at anything else that could be making your asthma worse, such as acid reflux or GORD (gastro-oesophageal reflux disease).

Ask you GP or nurse to update your asthma action plan with new food triggers and any action you need to take if your asthma symptoms are triggered by food. 

Home allergy tests

You can buy home allergy tests, but there is little evidence to suggest they are accurate. They may suggest you avoid lots of different foods which can be bad for you as you will miss out on important vitamins and minerals.

Here are five more things you can do to lower your risk:

1. Avoid the foods you know you’re allergic or sensitive to.  
2. If you have a preventer inhaler or a MART inhaler, use it every day as prescribed, even if you feel well.  
3. Read food labels carefully. The 14 major allergens are listed in bold on pre-packaged foods. If you’re allergic or sensitive to foods that are not on this list, carefully check all the ingredients on the label.  
4. If you’re eating out at a restaurant or cafe, tell all staff about your food allergy.
5. Share your asthma action plan with your family and friends so they know how to help you in an emergency.

“It’s important that you manage your asthma and food allergy or intolerance together to cut the risk of one making the other worse. If you have a food allergy and your asthma’s not well controlled, it increases your risk of having a severe allergic reaction” says Dr Andy Whittamore, Asthma + Lung’s GP.