Food additives play a key role in maintaining the food qualities and characteristics that consumers demand, keeping food safe, wholesome and appealing from farm to fork. They carry out a variety of useful functions which we often take for granted. Foods are subjected to many environmental conditions, such as temperature changes, oxidation and exposure to microbes, which can change their original composition.
An additive is described as "any substance not normally consumed as a food in itself and not normally used as a characteristic ingredient of food, whether or not it has nutritive value, the intentional addition of which to food for a technological purpose in the manufacture, processing, preparation, treatment, packaging, transport or storage of such food results, or may be reasonably expected to result, in it or its by-products becoming directly or indirectly a component of such foods" (Regulation (EC) 1333/2008). Many food additives are naturally occurring and some are even essential nutrients; it is the technical purpose that leads to these being classified as food additives and given an E-number.
Food additives are very carefully regulated and the general criteria for their use is that they perform a useful, technological purpose, are safe and do not mislead the consumer. In Europe all food additives are clearly labeled by law, so those with specific sensitivities and those who believe they have sensitivity to a food additive, can readily avoid those.