Food and asthma
Food is not a common trigger for asthma. In fact, foods, drinks and food chemicals affect fewer than 5% of people with asthma (fewer than 2% of adults and fewer than 5–6% of children).
People with asthma should consume a varied and nutritious diet, including breads and cereals, fruits and vegetables, lean meats, and dairy foods.
Some ingredients in processed foods can set off wheezing in people who are sensitive to these substances. The most common food additive to cause asthma symptoms is metabisulphite, a preservative used in dried fruit and wine. If you have troublesome asthma, it might be worth avoiding foods containing sulphites.
Food allergies and asthma
On their own, food allergies rarely cause asthma. Vomiting and hives are the most common reactions to food allergies. Foods may, however, trigger asthma as part of a generalised severe food allergy reaction involving other symptoms in the skin and gut.
Despite what many people think, cow’s milk and other dairy foods rarely trigger asthma symptoms in people without milk allergy.
A range of factors can cause bad reactions to food; from allergy to intolerance or enzyme deficiencies.
Of the most common causes of food allergy, most children grow out of their allergy to milk, eggs, wheat and soy. In the case of milk allergy, nearly 90% of children lose their allergy by the age of five.
Allergies to peanuts, tree nuts (such as almonds and cashews), fish and shellfish can be lifelong. These are also the most common foods to cause life-threatening anaphylaxis, the severest allergic reaction.
Food intolerances and enzyme deficiencies (when your body cannot process certain substances) are sometimes mistaken for food allergies. In general, these reactions tend to cause headache, bloating and stomach upset, and are less severe than allergic reactions. They do not cause anaphylaxis.
These food sensitivities include lactose intolerance, gluten intolerance (coeliac disease), and sensitivity to some artificial colours, flavours and preservatives.
Identifying the culprit
Your doctor can help you identify the cause of your food reaction, to find out if you have an allergy or sensitivity.
If foods or food additives are suspected as triggers for your asthma, you may need to be referred to an allergy specialist for further detailed assessment. If foods are confirmed as triggers, your allergy specialist may recommend a dietitian for advice.
Once the culprit is identified, you should avoid those foods known to cause a reaction. For some people with intolerance or sensitivities, small amounts may be OK or cause only mild discomfort. However, for some people with allergies, even the slightest exposure may cause serious or life-threatening problems.