Non-allergic food hypersensitivity (formerly food intolerance)
Other reactions to food than food allergy include being poisoned e.g. by bad mussels, and non-allergic food hypersensitivity. In this section you can learn more about the latter. Non-allergic food hypersensitivity has previously sometimes been called food intolerance. In non-allergic food hypersensitivity, the immune system is by definition not affected.
Usually the symptoms in non-allergic food hypersensitivity are milder and take longer to appear after eating the offending food compared to the symptoms of food allergy. In addition someone with this condition usually has to eat much more of the offending food before developing symptoms. However, you cannot discriminate between non-allergic food hypersensitivity and food allergy based on the symptoms alone.
Non-allergic food hypersensitivity has previously sometimes been called food intolerance.
Two examples of food substances that can cause non-allergic food hypersensitivity are the widely used food preservative, sulphite, as well as the milk sugar, lactose.
Lactose intolerance is the normal condition in 75% of the human population, but is relatively rare in northern Europeans probably occurring in 3-6% of the population. It is a hypersensitivity to the lactic sugar (lactose) in milk. It is different from cows’ milk allergy, which is a reaction to the proteins in milk. Lactose intolerance occurs when a person produces insufficient of the digestive enzyme, lactase. Lactase breaks lactose down into its component sugars in order for the body to absorb it through the intestinal wall. Its lack means lactose is not absorbed properly. Bacteria ferment the non-absorbed lactose in the large bowel. The bacteria produce gas which leads to stomach ache, bloating and diarrhoea after ingestion of normal portions of dairy products.