Key points

  • Food intolerance is the general term used to describe a range of adverse responses to food, including allergic reactions, adverse reactions resulting from enzyme deficiencies, pharmacological reactions and other non-defined responses.
  • An allergic reaction to a food can be described as an inappropriate reaction by the body's immune system to the ingestion of a food.
  • Allergic reactions to foods vary in severity and can be potentially fatal.
  • Any food has the potential to cause an adverse reaction. Foods that commonly induce adverse reactions include milk, gluten containing cereals, nuts, peanuts, eggs and shellfish.
  • Symptoms of food intolerance can overlap with those of more serious conditions, making use of appropriate diagnostic procedures is particularly important.
    Most people can eat a very wide range of foods without any problems although they may have likes or dislikes that influence what they choose. However, some people react badly to certain everyday foods and eating them may cause uncomfortable symptoms or, in rare cases, a severe illness.

There are many different reasons for unpleasant reactions to food. Apart from food poisoning, the main causes are referred to as food intolerances. This term includes a number of different types of reaction including food allergies, which are reactions that involve the body’s immune system. But most food intolerances are not true allergies, although they may cause uncomfortable or distressing symptoms.

It is not known exactly how many people in the UK have a food allergy. Population studies in the UK using conventional testing procedures suggest that between 1 and 2 people in 100 (1-2%) have a food allergy that can be diagnosed reproducibly, whereas as many as 30 in 100 (20-30%) ‘believe’ themselves to be allergic or intolerant to one or more foods.

It is important that people who think they suffer from a food allergy or other food intolerance seek professional advice from their GP before changing their diet dramatically and risking it becoming unbalanced. Dietary change prior to tests can make diagnosis more difficult, for example in the case in coeliac disease.