Although allergies have been identified as an asthma trigger, they won't cause asthma on their own. In fact, not all allergic people have asthma, and many asthmatics are not allergic.
Food allergy is not a particularly common cause of asthma. It only affects about one per cent of children and 0.05 per cent of adults. Inhaled food allergens, such as housedust mites, cat fur and pollen, are more likely to trigger an asthma attack than are foodstuffs.
Some people may be sensitive to some additives and preservatives. It has been estimated that about five per cent of asthmatics are sensitive to sulphur-containing compounds (especially sulphites), which are added to foods to prevent them from becoming oxidised and contaminated with microbes.
When sulphites are present in a final food in amounts more than 10 ppm (parts per million), the food label must carry the chemical name and purpose of the additive (for example, potassium bisulphate as a preservative). Food-labelling protection regulations exclude sulphite-treated foods that are served as 'fresh', such as salad-bar ingredients, and menu items that are delivered to restaurants pre-prepared. Here, sulphites are used to preserve, for example, the crispness of green salads, or the whiteness of peeled, uncooked potatoes.
Asthma can also be triggered by the preservative sodium benzoate (found in fruit juices, soft drinks and foods with fruit), colourants like tartrazine, flavour enhancers like MSG (monosodium glutamate) and salicylates (found in aspirin).
The prevalence of food anaphylaxis due to masked allergens contaminating certain manufactured products has increased over the last 10 years. One study, which aimed to test levels of sensitivity to egg, peanut, milk and sesame seed, showed that respiratory symptoms were observed in 12 per cent (egg), 20 per cent (peanut), 10 per cent (milk) and 42 per cent (sesame), with subjects being highly sensitive to relatively low levels of the allergens.Back to How You Beat Asthma