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More detail on individual foods can be found in our knowledgebase (link to as relevant) which houses a wealth of information as well as our Factsheets on individual allergens.
You can also find out about legislation on food allergens (link to “legislation on allergens” in the knowledgebase).
In most cases of food allergy, there is no reason to suppose that the patient will ever experience anaphylaxis but anyone who is worried should seek a GP’s advice and then be referred to an allergy clinic. Where a severe reaction is thought likely to occur, the dietary exclusion of the offending food needs to be absolute. To achieve this while ensuring the diet is as wide as possible, detailed dietetic advice is needed.
A wide range of foods and substances can trigger anaphylaxis, but the most common culprits in the UK are peanuts, tree nuts (such as almonds, Brazils, hazelnuts and walnuts), sesame seeds, shellfish, fish, eggs and milk.
Management of nut allergy and peanut allergy involves strict avoidance and self-treatment to deal with inadvertent exposures.
When buying pre-packaged foods, ingredient labels need to be checked thoroughly. Peanuts can appear under the names groundnuts and monkey nuts, and they may turn up among mixed nuts. Heating may reduce the allergenicity of heat-labile allergens (e.g. some of the allergens in fruits) but increases the allergenicity of peanuts and tree nuts.
People should watch out for satay sauce (made with peanuts), pesto sauce (made with tree nuts) and marzipan and praline (confectionery products made with nuts). Salad dressings may contain nut oils.
Curries and other Eastern dishes are high risk because many of them contain peanuts or tree nuts and their presence may not be obvious if the food is spicy.
Patients are advised to be direct with staff in restaurants or other catering outlets and point out the seriousness of their allergic condition. If staff cannot give an assurance that a specific dish is safe, it is best to eat elsewhere.
‘May contain’ labels are generally used where there is a known or suspected risk of contamination. Nut traces do sometimes occur, so it is best to avoid all foods carrying such a warning.
Research into the allergenicity of peanut oil (Hourihane et al, 1997) took place in Southampton and was published in the British Medical Journal (BMJ). The researchers conclude that refined peanut oil will not cause allergic reactions for the overwhelming majority of acute peanut allergic individuals, and if anyone does suffer a reaction it is likely to be mild. However unrefined (crude) peanut oil will cause reactions. Despite this reassurance, European (and UK) legislation states that all peanut oil, whether refined or unrefined, must be declared whenever it appears in pre-packed food.
Peanuts (Arachis hypogaea) are actually legumes but most people with peanut allergy can eat other legumes (such as peas, beans and lentils) without problems. US researchers found that five per cent of their selected population of legume reactive children had symptoms with multiple legumes (Bernhisel-Broadbent and Sampson, 1989).
A significant proportion of people with peanut allergy react to tree nuts and vice versa. If you are uncertain about your own case, a referral to an NHS allergy clinic is particularly important.
Doctors often advise that people who are allergic to one tree nut should avoid all other tree nuts. There are a number of reasons for this: A person allergic to one nut may become allergic to others in due course; one nut may be sold as another (e.g. almond desserts sold in restaurants may actually contain peanuts); and nuts may be stored together and therefore subject to cross-contamination.
Hourihane JO; Bedwani SJ; Dean TP; Warner JO (1997). Randomised, double blind, crossover challenge study of allergenicity of peanut oils in subjects allergic to peanuts. BMJ 1997 Apr 12;314(7087):1084-8.
Bernhisel-Broadbent, J. and Sampson, H.A., 1989. Cross-allergenicity in the legume
botanical family in children with food hypersensitivity. Journal of Allergy and
Clinical Immunology, 83 (2 Pt 1), 435-440.