Much of our concern about the potential health hazards associated with food additives is coloured by our perception of their chemical nature. People tend to associate chemicals with contamination, drugs, poisons and industrial processes. Their use in food does not fit well with the image of food as something which is natural, pure, nutritious and good to eat. But food itself is a complex mixture of chemicals and there is nothing inherently safe about naturally occurring chemicals in food. All food chemicals have the potential to cause unpleasant and, in some cases, even life-threatening reactions.

There are difficulties in establishing a definite relationship between a particular food additive and a response that occurs later and much of the research in this area lacks scientific rigour. The attention given to some studies in the popular press and on radio and television has alerted many doctors and other health professionals to the possible role of food additives in health problems. While the actual extent of food additive-related disorders in the general community appears to be very low, the impression that these disorders are common, and their diagnosis without critical appraisal and adequate testing can lead to unnecessarily restrictive and potentially nutritionally inadequate diets.

For a relatively small number of people food additives have been shown to be responsible for conditions including skin disorders (rashes, swelling, hives), respiratory disorders (asthma, hayfever, sinus trouble), digestive disorders (diarrhoea, abdominal pain) and may be involved in reactions such as irritability, sleep disturbance, and abnormal behaviour (hyperactivity). It must be stressed that there are other causes of these disorders which must be considered before effective treatment can start. In children, reactions to particular food additives sometimes disappear as they get older.

Diagnosis of food additive sensitivity requires careful interpretation of the nature, frequency, severity and duration of symptoms, dietary history, and the results from diets eliminating particular food(s) and challenge tests (which then reintroduce the suspected food or additive). Diets eliminating foods containing the suspect additive should he carefully planned to ensure that all required nutrients can be obtained in adequate quantities, and they should be maintained only under supervision by a dietitian or doctor. The systematic reintroduction of foods containing the offending additive can sometimes provoke serious reactions and should be done under medical supervision. Food additives most frequently implicated in adverse reactions are the yellow colouring tartrazine (102), benzoates (210, 211, 212, 213), monosodium glutamate (621) and the sulphites (220, 221, 222, 223, 224, 225, 228). For a full list of food additive code numbers see appendix 3.