Only seldom have
food additives been shown to cause true allergic (immunological) reactions. Adverse effects due to various pharmacological or other mechanisms are much more common. The individual tolerance may be decreased for one reason or another, and may fluctuate from time to time. Many patients suffering from
food additive reactions have atopic constitutions and such clinical symptoms as flexural
dermatitis,
rhinitis and
asthma. The most important skin symptoms caused by
food additives are
urticaria,
angioneurotic edema, and contact
urticaria.
Azo dyes,
benzoic acid and several other common
food additives may aggravate or, more rarely, even cause
urticaria. Spices are one of the most common causes of immunological contact
urticaria. Non-immunological contact
urticaria is produced by numerous spices,
benzoic acid,
sorbic acid,
cinnamic acid, and many
essential oils.
Asthma and
rhinitis are the main
hypersensitivity symptoms in the respiratory tract, and
azo dyes,
benzoic acid, and sulfitic
food additives are the most common causative agents. Systemic and respiratory reactions to
food colorants and
benzoates have been claimed to occur more frequently in
acetylsalicylic acid- (ASA-)sensitive patients than in non-reactors.
Hypersensitivity reactions in organs other than the skin and respiratory tract are rare or poorly documented. Psychological factors play an essential role in both food and
food additive reactions.