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Food Intolerance and Allergy |
Although precise statistics are lacking, there is a general consensus that allergic reactions, to whatever source, are increasing in the developed world. The term allergy is sometimes used loosely to mean any adverse reaction but allergy strictly means a condition in which an immunological reaction is produced. To do this the causative agent has to be a large biological molecule such as a protein. Other substances in food can sometimes cause intolerant reactions by purely chemical means. By far the greatest number of allergic reactions is produced by pollens and the house dust mite (about 20 per cent of the population are susceptible in developed countries) but some foodstuffs can cause significant numbers of cases. The incidence of general adverse reactions to foodstuffs in the general population is 1.4-1.8 per cent and eight foods account for 90 per cent of the food allergies in the developed world: peanuts, tree nuts (pecan, walnuts etc), fish, shellfish, eggs, milk, soya and wheat. The corresponding figure for additives is 0.01-0.23 per cent. In other words you are 8-100 times more likely to suffer a reaction to a natural foodstuff than to an additive. Of specific additives the ones most often cited as causing problems are the sulphite and benzoate preservatives and synthetic food colours, especially the yellow dye tartrazine (Diet, Behaviour and Hyperactivity). Sulphite - whether used as sulphur dioxide gas or as dissolved sulphites and metabisulphites - is a fairly cut and dried case. It aggravates asthma in about 4 per cent of asthmatics and in a few cases the reaction can be severe. The risk is doubled in steroid-dependent asthmatics. Because of the problems in this group sulphite levels in some food have been reduced over time: eg the maximum permitted level in red wine in Europe is 160 ppm against 500 ppm 100 years ago. But sulphite is one of the essential additives and is permitted for use in organic foods. It has a unique range of properties, being an antioxidant and a bleaching agent as well as a preservative. It has also been used as a preservative for thousands of years. Benzoates are derivatives of benzoic acid, which is found in many fruits, sometimes at levels far greater than would be permitted as an additive. The flavour enhancer monosodium glutamate (MSG), which has been in use since 1900, was suspected by some people for many years of being the cause of the so-called Chinese restaurant syndrome, a hot flushing reaction. Tests on people who claim susceptibility to this condition have never confirmed such a link. There will always be someone, somewhere, who is allergic to something - but the main food allergens have now been identified. They are the 'big eight' listed above, plus mustard, celery, sesame seeds and sulphite. Under new EC regulations that came into force in the UK and the rest of the EU in November 2005, pre-packaged foods containing any of these top 12 allergens will have to be highlighted on the label. A most welcome development for those who suffer from this problem. |