Deaths in children, adolescents, and adults who
ingested foods to which they were highly allergic have been reported.1,2
These deaths are often caused by a "hidden" ingredient in the food to
which the individual is allergic.1,3 Yunginger1 suggests
that in the United States, more children and adolescents die annually as a
result of food-induced anaphylaxis than as a result of insect stings. The
majority of these deaths are due to severe allergy to peanut and nuts, and
asthma appears to be an important risk factor for this form of allergy.2
Sensitivity can occur by ingestion of minute
quantities of food allergens4,5 and even by inhalation of food
allergens carried in air or in cooking fumes.6-12 The association
between a reaction and a food may not initially he obvious because many
patients experience a reaction only several hours later.13,14 Unlike
the very acute and often dramatic reaction to peanut, the form of reaction to
egg, milk, wheat, and soy may he through "soft signs" (e.g.,
gastroenteropathies, asthma, and atopic dermatitis).12 Other
diagnostic difficulties occur in individuals experiencing anaphylactoid
reactions and in patients with food-dependent exercise-induced anaphylaxis. 15
Reasons for allergens being Hidden in foods
Probably the most common reason for sensitive
individuals to ingest a hidden allergen is contamination of a safe food. This
occurs when the same serving utensils are used for different foods. Salad bars
and ice cream parlors offer good examples of this practice. It also occurs when
deli meat slicers are used for slicing both cheese and meat and when
manufacturers use previously manufactured products for manufacture of a
secondary product. Mayonnaise used in the manufacture of a new product may not
prompt the listing of mayonnaise or egg. particularly if this ingredient is
less than 2% of all the ingredients in the new product. Another form of
contamination occurs when a manufacturing plant uses the same equipment to make
different products, such as ice cream and milk-free sorbet, without adequate
cleaning of the equipment16 or when the same oil is used for cooking French
fries and fish in a take-away outlet.12
There are many other ways for allergens to he hidden
in food. Misleading labels may disguise hidden allergens. This can he
illustrated by nondairy creamers or coffee whiteners, which contain skim milk17
or by meat products that contain soy. Some margarine, claiming to consist of
100% corn oil, may in fact contain skim milk powder. A drink advertised for
"people who cannot drink milk" is actually milk with lactase enzyme
for individuals with a lactose intolerance, but it clearly still contains milk
protein.
Hidden allergens can also occur in processed food when
an ingredient is added for a specific application; for example, when egg is
used in food products and is listed on the ingredient panel as a binder,
protein, or emulsifier. This may also occur when soy is used for its
"texturizing" or emulsifying properties. Natural flavors such as
pineapple, milk casein, or hydrolyzed soy protein may be used and listed as flavoring
or natural flavoring, as in microwave popcorn.
Ingredient switching is another source of concern and
may happen when manufacturers change ingredients without making this clear on
the label. This can transpire when a shortage of vegetable oil results in substitution
with a tropical oil, or as noted previously, when a margarine manufacturer
advertises 100% corn oil but adds skim milk without altering the label.
Mistakes take place when consumers assume that a brand
of food that uses similar labels for a range of products has similar
formulations. Loopholes in labeling regulations allow allergens to be hidden in
a food product when a manufacturer is excused from listing an ingredient that
is present at less than a specific percentage of the total product.
Another major problem is that a food may be listed on
the product label by an uncommon term. This practice is addressed in this
article.
Food manufacturing practices vary throughout the
world, and because the importation of food is common practice, this review aims
to assist the individual with allergies and the traveller by including in the
tables as many sources of hidden food allergens as possible.
Problems relating to some specific foods
Egg
Egg is one of the most allergenic of all foods, and minute amounts of egg can result in symptoms within minutes, including life-threatening anaphylaxis. This is also seen after contact with egg through non-oral routes.6,18-20 Reactions may occur the first time a child is given egg.21 Although ovalbumin, ovomucoid, and ovotrans-ferrin have been identified as the major allergens in egg white,21,10 other unnamed allergens of lesser importance have been identified.22 These allergens are also present in egg yolk but in lesser quantities.21
This is important because components of egg may be
individually used for specific actions in food preparation. For example, hen's
egg lysozyme is used as a preservative in food; and in some countries, notably Japan and Switzerland, lysozyme is used in
medications.23,24 Individuals sensitive to hen's egg have been shown
to be allergic to lysozyme produced from hen's egg.18,23-26
A variety of descriptions may indicate the presence of
egg protein in a product (Table 1). The function that egg performs in a product
may be named on the ingredient panel (e.g., binder, emulsifier, or coagulant).
Because legislation may permit a manufacturer not to list an ingredient
constituting less than a specific percentage of the total product, noodles
containing egg may not have egg listed on the ingredient panel. A similar
situation may occur when egg white is used to give pretzels, bagels, and other
baked goods their shiny appearance. In most products, lecithin is derived from
soy, but sometimes it may be egg-derived. Provitamin A (extracted from egg) may
be used and described as a colorant, but its antigenic properties are unknown.
In addition to food products (Table 2) that may be
dangerous to egg-sensitive individuals, egg proteins are also found in
cosmetics, shampoos, and pharmaceuticals, such as the laxative Agarol. A
patient allergic to egg should avoid buying fried foods from vendors who use
the same frying surface for preparing multiple types of food. Recent evidence
suggests that egg-sensitive children can receive measles immunization safely.27
Although rare, avian proteins can induce egg allergy
in susceptible individuals.28-31 It has been suggested that duck egg
be substituted for hen's egg in egg-sensitive individuals. These individuals
are able to tolerate cooked chicken.32
TABLE I
Labels that may indicate the presence of egg protein
Labels that may indicate the presence of egg protein
Albumin
Binder Coagulant Egg white Egg yolk or yellow Emulsifier |
Globulin
Lecithin Livetin Lysozyme Ovalbumin Ovamucin |
Ovamucoid
Ovovitellin Powdered egg Vitellin Whole egg |
References 32,37,80,90
TABLE II.
Foods that may contain egg protein
Foods that may contain egg protein
Baked goods (most except some breads)
Baking mixes Batters Bearnaise sauce Bouillon (in restaurants to clear it) Breakfast cereals Cake flours Candy (see Sweets) Cookies Creamy fillings Custard Egg noodles Eggnog French toast Hollandaise sauce Ice cream Lemon curd Macaroni Malted cocoa drinks (e.g., Ovaltine, Ovamalt) |
Marshmallows
Mayonnaise Meringues Muffins Noodles (egg) Omelettes Pancakes Processed meat products (e.g., bologna, meat loaf, meatballs, sausages) Puddings Salad dressing (creamy) Sherbets Souffles Soups Spaghetti Sweets (e.g., fondant creams, truffles, marshmallows, etc.) Tartar sauce Turkish Delight Waffles Wines (if cleared with egg white) |
References 32,91
Milk
Patients with very sensitive milk allergy can react to a very small
quantity of milk protein, including minor contamination13 and even inhalation
of milk powder.7
Milk may be found in a large variety of processed
foods (some obvious and others not), including confections, margarine, cheese,
and pies (Table III). Cheese and cream contain milk protein and should be
avoided. Milk contamination of a product is possible if the same manufacturing
equipment is used for various products. There is also a carryover effect when
one product is used in the manufacture of another.16 In addition, patients
should be careful when ordering sliced products from outlets that use the same
slicers for cutting a variety of foods (e.g., cheese and cold meat). Lactose,
which may contain residual milk protein,may be found in foods and as a filler
in the manufacture of medicines such as Benadryl capsules (United States).
Hypoallergenic milk formulas have been used as a milk
replacement for children with milk hypersensitivity. However, hypoallergenic
milk formulas are not non-allergenic, and many children react to these,
depending on the particular formula.33-36
Common descriptions on ingredient panels are
"milk," "pasteurized milk," "full cream milk
powder," "dried milk," and "skim milk powder" (Table
IV).
Extracted milk proteins added to foods retain their
antigenicity and may be described as "casein," "caseinate,"
"whey," or "whey powder."
In our community, many individuals consider skim milk
and skim milk powder not to be milk and substitute these for milk. In some
instances milk is used in emulsions and can be described as
"caseinate," "emulsifier," or "protein."
Soy products are often purchased by those specifically
avoiding cow's milk, with the assumption that a soy-based product is free of
cow's milk protein. This is not true. "Vegetarian" cheese may contain
cow's milk protein. This term simply means that the rennet used in its
manufacture is of vegetable origin.37
TABLE III.
Foods that may contain milk protein
Foods that may contain milk protein
Batter-fried foods
Biscuits Bread Breakfast cereals Cakes Chocolate Cookies Cream sauces Cream soups Custard Fish in batter Gravies and gravy mixes Ice cream (and "non-milk" fat) Imitation sour cream Instant mashed potatoes |
Margarine
Muesli Muffins Other baked goods Packaged soups Pies Puddings Rusks Sausages Sherbet Soy cheese Soup mixes Sweets Canned soups Vegetarian cheese |
References 17,32,90,91
TABLE IV.
Labels that may indicate the presence of milk protein
Labels that may indicate the presence of milk protein
Artificial butter flavor
Butter Butter fat Buttermilk solids Caramel color Caramel flavoring Casein Caseinate Cheese Cream Curds "De-lactosed" whey Demineralized whey Dried milk Dry milk solids Fully cream milk powder High protein flavor Lactalbumin |
Lactalbumin phosphate
Lactose Milk Milk derivate Milk protein Milk solids Natural flavoring Pasteurized milk Rennet casein Skim milk powder Solids Sour cream (or solids) Sour milk solids Whey Whey powder Whey protein concentrate Yogurt |
References 32,80,90
Soy
Because of the almost unlimited uses of soy, it is a particularly insidious hidden allergen. As with many other allergens, reactions may occur to very small quantities of soy protein, and anaphylaxis to soybean protein has been reported.2,38,39
Soybean lectin is also an important allergen and has
been associated with allergic reactions.40
Soybeans may be ingested as whole beans, as flour, or
as oil. In addition, soy can be used in the manufacture of food in a great
variety of ways, including as a "texturizer," emulsifier, and protein
filler. Soy may thus be listed on the ingredient panel according to its use
(e.g., "hydrolyzed protein" or "lecithin"39)
(Table V).
Soybean flour is often added to cereal flour and is
used extensively in the baking industry. The majority of breads contain some
soy flour. Pastries, cakes, biscuits, and baby foods may contain soy flour. It
is also used in the manufacture of sausages, processed meats, hamburgers, and
other meat products" (Table VI). Fermented soybean may be used in the
preparation of soy sauce or Worcestershire sauce. Fermented soy is in wide use
as a food in the Far East.
Soy is so widely distributed in processed foods that
avoidance of soy in the diet is very difficult. Soy may find its way into a
food product when added as a "compound" ingredient. For example, if
margarine is added to a food product it will be listed as such, but soy present
in the margarine itself will not be listed on the ingredients panel.
Soy protein isolate or concentrate may be used to
emulsify fat in food products and may thus be used in the manufacture of ice
cream, mayonnaise, and a variety of other liquid fat- or oil-containing foods.
The concentrate or isolate may also be used in soy milk and as a protein
concentrate added to health foods and high-protein biscuits. Other foods that
may contain soy include pureed and cereal baby foods, margarine, and white and
brown bread39 (Table VI).
Other uses for soy include the manufacture of tofu
(soybean curd), which may in turn be used for the manufacture of soy-based ice
cream. Soy may be converted into products having a meat-like texture.41
This "textured vegetable protein" is used in simulated meat products
or may be added to meat as an extender. These products are often used as meat
substitutes in vegetarian products and in catering establishments, including
hospital and army food services, and feeding programs.
The seeds of soybeans are widely used as a source of
oil. The oil has many uses (e.g., in salad dressings, margarine, baby foods,
industrial components, linoleum, paint, plastics, soap, and glue for plywood)
(Table VII). Although soybean oil was initially thought to be safe for
soy-sensitive individuals,42 it is now evident that soy protein may
occur in soybean oil.43 Thus the allergenicity of soybean oil would
depend on its purity, which in turn depends on the extraction process. Recent
evidence has demonstrated that although oxidized soybean oil may not show
allergenicity, proteins in soybeans are capable of interacting with oxidized
lipid to form products that are allergenic to soybean-sensitive patients.44
Indeed, Hiyama et al.45 report a case of urticaria associated with
paren-teral nutrition with an intravenous 10% lipid emulsion containing a
soybean oil base. Such reactions, however, appear to be uncommon, and there are
very few reports of this nature in the literature.
Soy products are often purchased by those specifically
avoiding cow's milk, often with the assumption that a soy-based product is free
of cow's milk protein. This may not always he true, and caution is required.
Again, labels should be read carefully, and they should, of course, contain the
correct declaration.
Thickeners, stabilizers, emulsifiers, and bulking agents
may be manufactured from a variety of other members of the legume family in
addition to soybeans. On the basis of in vitro studies, Barnett et al.46
suggested that there may be cross-reactions between soy and other members of
the legume family (Table VIII). Further evidence for broad cross-reactivity has
been provided by RAST and skin prick tests: however, it is rare to have
symptomatic reactivity to more than one member, and clinical hypersensitivity
to one legume does not require elimination of the entire legume family.47,48
Carob, derived from the carob bean. is used commonly as a chocolate substitute,
and one should possibly guard against cross-reactivity to this legume. Peanut
sensitivity is discussed below.
TABLE V.
Labels that may indicate the presence of soy protein
Gum arabic
Bulking agent Carob Emulsifier Guar gum Hydrolyzed vegetable protein (HVP) Lecithin* Miso MSG (Monosodium glutamate) ! Protein Protein extender Soy Flour Soy nuts Soy panthenol |
Soy protein
Soy protein isolate or concentrate Soy sauce Soybean Soybean oil Stabilizer Starch Textured vegetable protein (TVP) Thickener Tofu Vegetable broth Vegetable gum Vegetable starch |
References 39,90,92
* Mostly produced from soy but may be manufactured from egg.
! Sometimes produced from soy or wheat but now mostly by synthetic means.39
* Mostly produced from soy but may be manufactured from egg.
! Sometimes produced from soy or wheat but now mostly by synthetic means.39
TABLE VI.
Foods that may contain soy protein
Foods that may contain soy protein
Baby foods
Bakery goods* Black pudding Bread (esp. high-protein bread)* Breakfast cereals (some) Burger patties Butter substitutes Cakes Candy Canned meat or fish in sauces* Canned or packaged soups* Canned tuna Cheese (artificial) made from soybeans* Chinese food |
Chocolates (cream centers)
Cookies Cooking oils Crackers Desserts Gravy (sauce) powders Hamburger patties Hot dogs Hydrolyzed vegetable protein (may be wheat) Ice cream Infant formula (including cow's milk formula) Liquid meal replacers Margarine Meat products (e.g., sausages, pastes. Vienna sausages [wieners]) Muesli |
Pies (meat or other)*
Powdered meal replacers Salad dressings Sauces (e.g.. Worcestershire, sweet and sour, HP.,Teriyaki) Seasoned salt Shortenings Snack bars Soups Soy pasta products Soy sauce Soy sprouts (Chinese restaurants) Soybeans Stews (commercial) Stock cubes (bouillon cubes) Tofu Tofutti TV dinners |
References 39,90,91
* May be present because of soya in the flour used.
TABLE VII.
Other sources of contact with soy
Other sources of contact with soy
Adhesives
Blankets Body lotions and creams Dog food Enamel paints Fabric finishes Fabrics Fertilizers Flooring materials Lubricants Nitroglycerine Paper Printing inks Soaps |
Reference 93
TABLE VIII.
Members of legume family
Members of legume family
Beans
Aduki beans Broad bean Black turtle bean Black-eyed bean Chick pea Cowpea Fava bean Garbanzo bean Great Northern bean Green bean Kidney bean Lima bean Mung bean Navy bean Pinto bean Snap bean String bean Wax bean |
Other members
Alfalfa (sprouts) Acacia (gum) Carob (chocolate substitute) Cassia or senna (in laxatives, curry, cinnamon) Fenugreek (used in curries, cinnamon, primary flavoring in imitation maple syrup) Lentils Masur bean Licorice Pea Green pea Purple-hull pea Peanut Senna or cassia (in laxatives and Epsom salts) Soybean Tamarind Tragacanth (gum) |
References 46,47,90
Wheat
Wheat is the most allergenic of all cereals. lgE antibodies have been demonstrated lo many components of wheat kernels, including albumin, globulin, gliadin, wheat germ agglutinin, a concanava-lin A-purified glycoprotein, and a trypsin inhibitor.49-52 Wheat is most rich in gluten, with the other grains containing a lesser mixture of gluten and gliadin. In addition to being present in all wheat-based food products, wheat gluten is frequently added to baked products made from other grains, including those made from soy flour.
Wheat-sensitive individuals should avoid a product
that includes other flours, because it is likely that at least some wheat flour
or a derivative will also be present.53 Even "gluten-free"
bread may contain small amounts of part of the wheat family.49,56
Spelt may better be described as nonhybridized wheat.56 No data have
indicated differences in the allergenic profiles of the various wheat
varieties, and they should all be viewed as potential allergens.
Hydrolyzed wheat proteins can be used in processed
foods for flavoring purposes (e.g., in meat flavorings) or as a binder in
vegetarian burgers. In the United
States legislation dictates that this form
of wheat must be labeled as wheat-derived, but this is not always the case in
other countries. Wheat can appear under various names on ingredient panels
(Table IX) and can be found in many food products (Table X). Gluten finds its
way into a few pharmaceutical products (e.g., Dimetapp LA, Nu-lacin, and
Fybranta).57
Buckwheat is not a member of the grass family and is
thus not a true cereal.58 The grain may be used for human food in
various forms from pancake flour to buckwheat noodles and baby foods58
For the wheat-hypersensitive individual, products made
from oats, rice, rye, barley, or corn or speciality foods made for
gluten-sensitive individuals generally may be used instead of wheat. However,
cross-reactions, although unusual, may occur between wheat, barley, rye, maize,
rice, and sorghum,8,59,60 as well as between the pollens of cereals
and cereal flours.61
TABLE IX.
Labels that may indicate the presence of wheat protein
Labels that may indicate the presence of wheat protein
All-purpose flour
Bleached flour Bulgur (cracked wheat) Bran Cornstarch Couscous Durum wheat Enriched flour Farina Gelatinized starch* (or pre-gelatinized) Gluten Graham flour Hard durum flour High gluten flour High protein flour ! Hydrolyzed vegetable protein ! Kamut Miller's bran |
Modified food starch*
Modified starch* MSG (monosodium glutamate)** Protein Semolina Spelt Starch* Unbleached flour Vegetable gum* Vegetable starch* Vital gluten Wheat bran Wheat flour Wheat germ Wheat gluten Wheat starch White flour Whole wheat Whole wheat flour |
References 48,49,54,55,57,80,90
* May indicate the presence of soy protein50
or may he manufactured from cassava (tapioca), maize, or rice.
! Sometimes produced from soy or wheat but now mostly by synthetic means.
** May be soy.
or may he manufactured from cassava (tapioca), maize, or rice.
! Sometimes produced from soy or wheat but now mostly by synthetic means.
** May be soy.
TABLE X.
Foods that may contain wheat
Alcoholic beverages
(made from grain alcohol) Ale Beer Wine Bourbon Whiskey Baked goods Biscuits Breads (including rye bread) Cakes Cookies Crackers, etc. Baking mixes Barley bread and drinks Battered foods Bouillon cubes Breaded meats Breaded vegetables Breakfast cereals Candy or chocolate candy Canned processed meat Cereal grains Couscous |
Gravy
Hot dogs Ice cream Ice cream cones Luncheon meats Licorice Macaroni Malt Malted milks (e.g., Horlicks) Milk shakes Noodle products Pasta (noodles, spaghetti. macaroni) Pepper (compound or powdered flour filler) Pies Processed meats Sausage Semolina Snack foods Spaghetti Soup mixes Soups Soy sauce Tablets |
References 57,90,91
Peanut
Peanuts are one of the most allergenic foods,62,63 and peanut allergy is one of the most common food allergies.64 Peanuts are probably the most common cause of death by food anaphylaxis in the United States, and about one third of peanut-sensitive patients have severe reactions to peanuts.65,66 Peanuts are added to a large variety of processed foods (Table XI). These include ice cream (as a flavoring), marinades, snack foods, and biscuits. Peanuts can be used as a flavoring or a seasoning agent67 and may be labeled as such (Table XII). Nuts may be used in the manufacture of vegetable burger patties.68 A fatal reaction to peanut antigen in almond icing has been recorded.69 Peanut butter may also be used to "glue down" the ends of egg rolls to keep them from coming apart.70 Some individuals do not know that peanut butter is commonly used in Oriental cooking.
Peanuts can be "deflavored,"
"reflavored," and pressed into other shapes such as almonds and
walnuts.9,65 These products retain the allergenicity of the peanut.
Some patients with peanut allergy also react to sweet lupine seed flour, which
may be used, for example, to fortify a spaghetti-like pasta.71
Although uncommon, a peanut protein hydrolyzate may
also be used in soft drinks as a foaming agent or in confections as a whipping
agent.67
Peanut oil has been considered to be devoid of
allergenicity,72,73 and this was initially confirmed by double-blind
crossover studies.74 However, peanut oil allergenicity is clearly
process-related, because cold-pressed peanut oils may contain peanut allergen.75
Moneret-Vautrin et al.76,77 confirmed the allergenicity of peanut
oil in milk formulas, and 11 of 45 brands of milk formulas in France contained
variable amounts of peanut oil.77 Residual peanut proteins arc
believed to become more allergenic with heating.77
The oil is frequently used in the preparation of so-called
"health foods." The oil can be used for many nonfood products, which
may, on contact, affect sensitive individuals. Like peanut oil, other vegetable
oils such as soy, maize, sesame, and sunflower oils contain very low quantities
of protein.78,79
Individuals who are allergic to peanuts are said to
not be allergic to nuts such as almonds, pecans, or walnuts; and these nuts can
be substituted for peanuts.9 This is contradicted by a recent study,
which showed that 50% of individuals allergic to peanuts reported allergic
reactions to other nuts as well.70 These findings were not validated
by further clinical investigation.
TABLE XI.
Foods that may contain peanut or peanut oil.
Foods that may contain peanut or peanut oil.
Baked goods
Baking mixes Battered foods Biscuits Breakfast cereals Candy Cereal-based products Chili Chinese dishes Cookies Egg rolls Ice cream |
Margarine
Marzipan Milk formula Pastry Peanut butter Satay sauce and dishes Soups Sweets Thai dishes Vegetable fat Vegetable oil |
References 66,70,72
TABLE XII.
Labels that may indicate the presence of peanut protein
Labels that may indicate the presence of peanut protein
Ground-nut
Peanut Peanut butter Emulsifier (uncommon) Flavoring Oriental sauce |
Reference 67
Fish
Fish are one of the most common causes of food
allergy, particularly in adults and in Scandinavian countries.9 Fish may find
their way into processed foods in raw, powder, or oil form. In the majority of
instances, this substance is clearly labelled as "fish" or with
another obvious descriptor. However, fish allergens may be found unlisted if
added as part of an oil. Fish products are not usually hidden ingredients but
may be hidden in Caesar salad dressing or in Worcestershire sauce if it
contains anchovies.9
Some seafood flavors (e.g., shrimp) arc added to food
in the form of a powder manufactured from the seafood's shell. Shrimp antigen
II is heat stable."' A variety of antigens are shared by several
crustaceans including shrimp, prawns, crabs, lobsters, and crayfish (crawfish).
At present, some manufacturers are researching the
possibility of adding fish meal (flour) to bread as a source of omega-3-fatty
acids (personal communication, M. M. Melnyczuk). Skin prick tests and RASTs
indicate extensive cross-reactivity among fish species, but recent research
suggests that patients may be able to consume some species of fish despite
positive test responses to one or two.81 However, it is generally recommended
that patients allergic to fish avoid all fish species.
DIAGNOSIS
A major difficulty in identifying a food allergen in some patients is that they may he unaware of the connection between a specific food and allergic symptoms, because the symptoms may appear much later.13,14 Although clinical history and routine laboratory studies have great predictive value in most individuals with food allergy, they may have little value in predicting which foods are responsible in many others, particularly in adults.64,82,83 Moreover, in some individuals with a history of a reaction to food, there may be poor correlation between history and results of skin tests, in vitro blood tests, and double-blind, placebo-controlled food challenges.64,84-86 The double-blind, placebo-controlled food challenge remains the gold standard in the diagnosis of food hyper- sensitivity, and in the event of negative skin prick test and RAST results, may be the only method with which to confirm a food hypersensitivity.87,88
A major difficulty in identifying a food allergen in some patients is that they may he unaware of the connection between a specific food and allergic symptoms, because the symptoms may appear much later.13,14 Although clinical history and routine laboratory studies have great predictive value in most individuals with food allergy, they may have little value in predicting which foods are responsible in many others, particularly in adults.64,82,83 Moreover, in some individuals with a history of a reaction to food, there may be poor correlation between history and results of skin tests, in vitro blood tests, and double-blind, placebo-controlled food challenges.64,84-86 The double-blind, placebo-controlled food challenge remains the gold standard in the diagnosis of food hyper- sensitivity, and in the event of negative skin prick test and RAST results, may be the only method with which to confirm a food hypersensitivity.87,88
PREVENTATIVE MEASURES
One clear message from the literature is that most fatal and near-fatal reactions happen when eating away from home.2,3,11,69,89 Individuals with severe food hypersensitivity should probably avoid processed foods. If it is necessary to purchase these foods, they should be made by a reliable manufacturer. Parents and children can learn to scrutinize food labels carefully. Unfortunately, the multiplicity of possible names for any one ingredient may let a hidden allergen slip by. If possible, hypoaller-genic formulas should be tested in each case before being prescribed for children sensitive to cow's rnilk.35,36 The very sensitive individual should wear a Medic Alert bracelet and carry an epinephrine (adrenaline) self-injector at all times.1 Less sensitive individuals may need to carry antihistamincs with them.
One clear message from the literature is that most fatal and near-fatal reactions happen when eating away from home.2,3,11,69,89 Individuals with severe food hypersensitivity should probably avoid processed foods. If it is necessary to purchase these foods, they should be made by a reliable manufacturer. Parents and children can learn to scrutinize food labels carefully. Unfortunately, the multiplicity of possible names for any one ingredient may let a hidden allergen slip by. If possible, hypoaller-genic formulas should be tested in each case before being prescribed for children sensitive to cow's rnilk.35,36 The very sensitive individual should wear a Medic Alert bracelet and carry an epinephrine (adrenaline) self-injector at all times.1 Less sensitive individuals may need to carry antihistamincs with them.
Fortunately, many individuals lose their reactivity to
foods over time, albeit not completely in some. Bock89 recommends careful and
periodic challenges in these patients to save families from prolonged anxiety
about accidental ingestion. Unfortunately, sensitivity to peanut is seldom
outgrown.66
Acknowledgement should be made to the food industry
for the strides made in improved labeling of food products, in many countries,
the food industry has played a leading role in constructing food intolerance
databases, which can assist sensitive individuals in avoiding foods containing
a particular ingredient. In the long term, manufacturers must he persuaded to
bring common ingredient names into use, and legislation should be passed to
make food labels more accurate. A possible solution would he to list the
derivative in brackets after the ingredient, for example, ovomucoid [egg].
I thank Dr. Sarah Ruden (Department of Classics,
University of Cape Town). Prof. Eugene Weinberg (Allergy Clinic, Red Cross
Children's Hospital, Ronde-bosch). Prof. Paul Potter (Allergology Unit.
University of Cape Town Medical School. Observatory). Tanya and Mikhailo
Melnyczuk of Roberts & Melnyczuk Food Research & Development
Consultants, and Ronn Timm (South African Association of Food Scientists and
Technologists and Royal Beechnut Pty. Ltd.) for their advice and expertise.
References
1.
Yunginger JW. Lethal food allergy in
children. N Engl J Med 1992;327:421-422
2.
Sampson HA, Mendelson L, Rosen JP. Fatal
and near fatal-induced anaphalaxis. N Engl J Med 1992;327:380-384
3.
Yunginger JW, Sweeney KG, Sturner WQ,
Giannandrea LA, Teigland JD, Bray M, Benson PA, York JA, Biedrzycki L, et al.
Fatal food-induced anaphylaxis. JAMA 1988;260(10):1450-1452
4.
Oppenheimer JJ, Nelson HS, Bock SA.
Christensen F, Leung DY. Treatment of peanut allergy with rush immunotherapy. J
Allergy Clin Immunol 1992;90:256-262
5.
Adkins FM, Wilson M, Bock SA. Cottonseed
hypersensitivity: New concerns over an old problem. J Allergy Clin Immunol
1988;82:242-250
6.
Blanco Carmona JG, Juste Picon S, Garces
Sotillos M, Rodriguez Gaston P. Occupational asthma in the confectionary
industry caused by sensitivity to egg. Allergy 1992;47(2 Pt 2):190-191
7.
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Journal of Allergy and Clinical Immunology 1996;98(2):241-250
with permission from Mosby-Year Book, Inc
Journal of Allergy and Clinical Immunology 1996;98(2):241-250
with permission from Mosby-Year Book, Inc