Fiona Angus investigates how food manufacturers can minimise the risk of allergic reactions to their products, as food allergy is the leading cause of anaphylaxis, causing an estimated 2,500 emergency room visits and up to 125 deaths per year in the United States.
In England one of the turning points for food allergy came in 1993. For many years an under-funded medical area, there was much that was not known about the cause, prevalence or management of this condition. People knew that it existed but generally thought of it as an extremely rare condition and certainly not one that could ultimately be fatal. The food industry was largely unaware of how food allergy could affect them and, whilst food companies had extensive food safety programmes, in reality little attention was paid to the issue at that time. The death of Sarah Reading in 1993 was the catalyst for change. Her death in a restaurant from an anaphylactic reaction to peanut, which had been put into a lemon meringue pie reached the national press and shocked the nation. How could a food consumed by so many be the cause of something so serious?
It also shook the food industry, especially when the facts about peanut allergy emerged — trace amounts could potentially cause death, the allergen was not destroyed by temperature, and there weren't yet any chemicals or processes that could reduce or eliminate its allergenicity.
Over the past eight years, quite a lot has been achieved. There is much better awareness about peanut and nut allergy and how it can be controlled. This has been very much down to the work of the Anaphylaxis Campaign, which under the helm of David Reading has done much to keep this issue in the public domain. Whilst the focus of attention has been on nuts — not surprisingly as they remain the allergen that continues to be the main cause of severe and fatal food anaphylaxis — we should be aware that peanut and nuts are not the only food allergens we should be concerned about.
To recap on the science; it is important not to confuse the terms food allergy and food intolerance. Food intolerance refers to any kind of reproducible unpleasant reaction to food, but it should only be called allergic if it is caused by an immunological response, often involving immunoglobulin E (IgE) antibodies that bind to the food. In reality, food allergy accounts for only about a fifth of all adverse food reactions.
The condition is associated with a wide range of symptoms. Most commonly, there will be a skin reaction like hives, followed by a gastrointestinal response, i.e. vomiting and diarrhoea. Severe symptoms include wheezing, coughing, respiratory stress and circulatory collapse. These are of most concern as they threaten life and are known as anaphylaxis. Reactions to stings and medicines are perhaps more common and better-known causes of anaphylaxis.
It has remained difficult to establish the prevalence of food allergy with any degree of certainty. Few population-based studies have been undertaken, as they are expensive, and require clinical testing to ensure accuracy. The studies that have been carried out however show that many people who think that they are allergic to food are mistaken. In the UK, we think that around 2 per cent of the adult population are food-intolerant of which only a proportion is truly allergic. Peanut certainly seems to dominate in terms of prevalence of food allergies in adulthood. In a study on perceived prevalence of peanut allergy carried out by Leatherhead in 1996, 0.4 per cent of British adults perceived themselves as allergic to peanuts. In young children, cow's milk allergy dominates, affecting up to 3 per cent of infants aged 0-2 years but most (though not all) cases resolve. Peanut and nut allergy are different from many other food allergies in that the allergy is usually not outgrown.
There is a long list of foods that are potentially allergenic and, in reality, you will find someone, somewhere with an allergy to a specific food. The most commonly allergenic foods are, however, egg, milk, fish, crustaceans, peanut, soya bean, wheat, and tree nuts. These "top 8" account for 90 per cent of all food allergies and so if as food manufacturers you can focus on managing these ingredients effectively, you are handling the majority of the problem.
In terms of fatalities, there are a variety of foods that have been implicated, although there are problems with the classification of this type of death, and many food allergy deaths are thought to be coded in the official statistics as asthma. Dr. Richard Pumphrey, at St Mary's Hospital, Manchester, has been compiling data since 1992 on fatal allergic reactions in the UK. According to his records, around a quarter of fatal allergic reactions are related to food. Peanuts and nuts cause most food allergy deaths in the UK. Other foods that have resulted in occasional food allergy deaths are milk, egg, fish and shellfish, banana, chickpea and nectarine.
To date, most (but not all) of the fatal food allergy cases have occurred out of the home in catering establishments. Nevertheless, there have been several deaths relating to packaged foods, and companies do sometimes receive complaints. The main tool available to the food industry to reduce the risk of allergic reactions to its products is accurate labelling, but cross contamination problems are very real in the factory environment and a broader approach is needed to minimise risks.
Since trace amounts of an allergenic food are sufficient to invoke a reaction, the use of shared equipment in the food-manufacturing environment is an area of concern. Where a food containing one of the main allergenic ingredients is being manufactured, the use of dedicated lines or even the restriction of highly allergenic foods to particular sites should be considered. This has been done by some companies for peanuts and nut products in order that they can produce guaranteed "nut-free products."
Often, however, this is not possible and so steps need to be taken to prevent cross-contamination from one production batch to another. Careful and thorough clean down between different product runs needs to be undertaken and simple things such as adding the allergenic ingredient late in the production process can help, as can scheduling the production of an allergen-containing food before a major clean down. It is also a good idea to use specific immunoassay kits to check for allergenic material in the first batch after changeover. Kits are available for most of the key allergens, including cows' milk, egg, hazelnut, peanut and soya. These kits can show if the cleaning process is effective and if cross-contamination is likely to be a problem.
Care is also needed with use of rework, as this can be particularly hazardous for an allergic individual. Companies need to develop clear rework policies, which are based on a like-into-like policy. In all cases, the on-pack labelling declarations must remain correct and the presence of all allergenic ingredients such as milk or eggs i.e. (not just nuts and peanuts), in the rework must be considered.
Product labelling needs to be clear and unambiguous. Trace allergenic ingredients should be labelled, even though there is not yet a mandatory requirement to do so. Manufacturers can also help allergic consumers by giving full information on the source of an ingredient, where a standard legal declaration may be unclear, e.g. lecithin should be labelled as soya or egg lecithin. Other labelling strategies that have been adopted are warning labels such as "contains peanuts" or "may contain peanuts". The former is thought to be useful as it alerts the allergic consumer to the presence of an allergenic ingredient in a product. This method has been adopted by some of the major retailers in the UK, including Sainsbury's. "May contain" labelling has, however, found its way onto a large range of products, which is not helpful to allergic consumers. The recommendation is that "may contain" labelling should not be used as a substitute for Good Manufacturing Practice and should only be used where absolutely essential.
Concern Over GM
An emerging area of concern, particularly in relation to functional foods, where innovative ingredients are an essential part of the development of the market, is that of the potential allergenicity of genetically modified and other novel ingredients.
The allergenicity of these novel ingredients needs to be carefully considered before they are used and consumed widely in foods. Certainly, allergy to peanuts seems to have risen in recent years in line with a dramatic increase in consumption, and therefore the important allergens of the future could be some of those foods and ingredients that are only now starting to become an important component of our diet.
Leatherhead Food Research Association