ugg i do Food allergens
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1. Differences between food allergy and food intolerance
For a small percentage of people, specific foods or components of food may cause adverse reactions. reactions which do not involve the immune system). a protein in a food, which in the majority of people will not produce an adverse reaction) sets off a chain of reproducible reactions involving the immune system. The reactions can be either antibody or cell mediated. The former is the most common and occurs in two stages3,4:
Sensitisation: Initial contact with an allergen does not evoke an allergic reaction but rather primes the immune system. Dendritic cells (a special type of white blood cells), which are found in numerous locations throughout the body including patches/pockets within the intestinal wall, play a pivotal role at this stage. When dendritic cells encounter foreign molecules they capture them and present them to other cells (T cells) of the immune system. In the case of an allergic individual, the immune system incorrectly identifies certain proteins as harmful. tissue cells). in a sensitised individual the allergenic protein cross links with the IgE antibodies on the surface of the mast cells causing release of histamine or other substances such as leukotrienes and prostaglandins. itching, swelling). due to amines such as histamine) or in some cases the mechanism may be undefined.7
This review deals only with food allergy.
2. Prevalence of allergies in Europe
The EuroPrevall study has been one of the most comprehensive research projects to evaluate the prevalence, basis and cost of food allergy. This multi disciplinary project which was funded by the European Union was launched in 2005 and completed in 2009. It involved partners from Europe and world wide.8,9 Regarding prevalence, there were 2 elements to this research: i) a literature review of more than 900 published studies on the prevalence of food allergies in Europe and ii) an actual study to establish the true percentage of infants, children and adults with food allergies across Europe. they were not confined to specific foods). In some studies, the food allergy was confirmed by a challenge test, a skin prick test or a blood test; however, in most studies the food allergy was self reported. In studies where the food allergy was clinically confirmed, the percentage of people reported to have an allergy ranged from 1 to 5%. self reported food allergy), the percentage ranged from 3 to 38%. However, only 1 to 11% of these people had their allergy confirmed. This shows the discrepancy between the percentage of people who think they have an allergy and the percentage of people who are actually diagnosed as allergic. Due to the high variability in results between studies and other limitations with the data, it was not possible for the researchers to use these data to calculate the overall percentage of people in the European Community with food allergies.10
The EuroPrevall study also established the true percentage of infants, children and adults with food allergies across Europe, through the EuroPrevall Birth Cohort and Community surveys. For the EuroPrevall Birth Cohort Study, a total of 12,049 babies and their families were recruited from 9 different countries. (11) Using standardised questionnaires and clinical assessments, this study investigated: i) the occurrence of food allergies in the first 2 years of life, ii) regional patterns of food allergy and iii) the role of parental, pre natal and early life risk and protective factors. The researchers found considerable differences between countries for a range of factors that are hypothesised to play a role in the development of food allergies. These included family history, obstetrical practices and pre and post natal environmental exposure.
The UK Food Standards Agency (FSA) is also involved in studies concerning food allergy and food intolerance.12 One of the studies funded by the FSA aimed to generate robust data on the prevalence of food allergy and food intolerance, in UK children,
and to compare these data with previous estimates to see if the prevalence is changing over time.13 In this study a whole population cohort of children on the Isle of Wight was followed from birth to 3 years of age. 91% of the target population). 83.3% of the target population) were seen every year. children aged 6 years (n=1440, 100% of the target population), 11 years (n=775, 47.4% of the target population) and 15 years (n=757, 50.2% of the target population) were also recruited. Data were collected using detailed questionnaires and reported food allergies were confirmed via skin prick testing and controlled food challenges. The study found that the prevalence had not changed over the past two decades. Furthermore, the study found that reported food allergies were common in all age groups; however, the percentage of confirmed food allergy was much lower (based on double blind placebo controlled food challenge and a good clinical history, it ranged from 3% for one year olds to 1.4% for eleven year olds). Based on this discrepancy the need for accurate diagnosis to prevent children being placed on unnecessary restricted diets was highlighted. those less than 18 years of age).17
3. hazelnut) were the most common allergen sources, often in association with pollen. Annex IIIa of Directive 2000/13/EC20, which applies until 13 December 2014 and Regulation No 1169/201121, which applies after that date). Two of these ingredients (gluten containing cereals and sulphur dioxide/sulphites) do not result in IgE mediated immune reactions but are termed allergens to simplify the legislation. These 14 specific ingredients (including those carried over in processing aids, additives and solvents) represent those that were the most common or serious causes of food hyper sensitivity in the EU at the time the legislation was developed and must be declared on the label when they are used in the production of a foodstuff. Declaration is not specifically required where one of the 14 ingredients is found at low levels as a result of cross contamination in a food, though the management of this situation is not harmonised throughout EU Member States and therefore handled in accordance with risk assessments in each individual jurisdiction.
Further detail on allergen labelling is provided in section 7.2.
Symptoms range from mild to severe. Different organs such as the skin, gastrointestinal tract, respiratory tract, eyes and central nervous system can be affected. Itching and/or swelling of the mouth are the most common symptoms. Anaphylaxis which causes severe and life threatening reactions occur in a small number of cases. Fortunately, most allergic reactions to food are relatively mild.6,22
Anaphylaxis is an acute, potentially life threatening condition. It can involve the cardiovascular system, the respiratory tract, the mouth, the pharynx and the skin, either singly or in combination. the mouth region). itchy skin). Symptoms from the mouth region include tingling and pruritus of the lips. swelling) of the larynx can cause difficulties swallowing and talking. Respiratory function may also be severely compromised. Respiratory symptoms include bronchospasm, cough and wheezing. These symptoms are often mistaken as worsening of pre existing asthma. In some cases, the initial symptom may be loss of consciousness.23
„Anaphylactic shock“ is a serious condition in which blood pressure drops rapidly and the sufferer could die from cardiac arrest unless adrenaline is administered soon after symptom onset in order to open up the airways and reverse vasodilation.6 Data collected in England and Wales since 1992 suggests that 20 deaths annually are attributed to anaphylactic reactions and that about one quarter of these reactions are due to foods.24 Anaphylactic reactions to food are associated with IgE mediated allergy. In Europe, peanut is the most commonly implicated foodstuff25; however, other food allergens may also cause anaphylactic reactions.23