Substances in foods that may trigger a food intolerance reaction.
Monosodium Glutamate (MSG, additive numbers 620 and 621) Glutamates also occur naturally in such foods as Camembert cheese, Parmesan cheese, tomatoes, soy sauce and mushrooms. MSG stimulates nerve endings, perhaps accounting for its function as a flavour enhancer when it is added to food.
Vasoactive Amines such as tyramine, serotonin and histamine are well known triggers of migraines in some patients and are present naturally in pineapples, bananas, baked meat, vegetables, red wine, wood-matured white wine, avocados, chocolate, citrus fruits and mature cheese. Amines can act directly on small blood vessels to expand their capacity, perhaps accounting for their effect on flushing, migraines and nasal congestion in some patients.
Salicylates are natural aspirin like compounds (aspirin was originally isolated from the willow tree bark) present in a wide variety of herbs, spices as well as fruit and vegetables. Reactions to these may be even more common than reactions to artificial colours and preservatives. Aspirin can trigger hives (urticaria) by acting directly on skin mast cells. Natural and structurally similar salicylates can also worsen hives in some patients.
Toxins Other than contamination of food with micro-organisms or their products (spoilage, food poisoning), some foods contain toxins than can cause severe symptoms. For example, if some types of fish are stored poorly, their gut bacteria can convert histidine to histamine, resulting in allergy-like symptoms.
Irritants. Caffeine and curry are gut irritants and can trigger indigestion in some people.