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Spices Allergy

The term spice contains an endless number of plant-derived ingredients used in the cuisine to refine foods. All parts of the spice plants from seeds, flowers, leaves, barks to rhizome or roots can be used for refinement of foods. In this overview, also celery, sesame and mustard which belong to the category spices, will be briefly touched too, even if detailed descriptions can be found in separate sections. Names, synonyms and biological classification of the most popular spices are given in Table 1.

Few spices are added raw to the dish. Many of them are used in dried or freeze-dried condition, as dill, parsley or celery, which then contain most of the allergic proteins also present in the raw spice. Allergens in pickled spices are unchanged or better conserved than in the dried ones, e.g. in the case of green versus black pepper. Additionally, mechanical grinding of the dried material may destroy some allergens, e.g. in the case of paprika, but still leave a considerable number of allergenic proteins. Roasted spices may keep their potential for allergenicity, as poppy seeds or sesame, the latter often consumed toasted on bread. Spice allergens can, therefore, be expected in raw, toasted, grilled, baked, cooked, tinned, pickled or dried food when eating out or at home, in freshly prepared or fast food.
 
Symptoms
Spices may produce mild symptoms: itching, swelling, burning at lips, tongue and palate or severe local reactions in and around the mouth: swelling of the throat, flush, breathing problems, stomach indigestion, vomiting, diarrhoea, and systemic reactions such as hayfever, asthma and anaphylactic shock.

How much is too much?
For most spices, the current scientific evidence is unsatisfactory to establish an intake threshold. However, for the spices taken up into the food allergen list of the EU (see below) some data on lowest reactive threshold are available since recently: for dried celery spice 160 mg, sesame 30 mg, and mustard 40 mg. Below, allergic reactions did not occur in the tested patients. It may be considered that thresholds for other spices may be comparably low and, consequently, low-dose challenge trials are recommended. 

Related foods (cross reactivity)
In most cases of reported spice allergy, IgE-cross reactions with pollen were reported. Especially birch pollen, and mugwort pollen allergy represents a risk for the development of reactivity to spices. Cross-reactivity to latex has been reported, too. The elicitors are plant proteins that are similar in different plants. Common reactivity is more likely in plants that are botanically closer related (Table 2). 

Who, when, how long, and how often?
Spice allergy represents 2% of all food allergy cases. It is rare in children and more prominent in adults. Allergic reactions can be seen as occupational allergy in spice factory workers. Besides allergic reactions also contact eczema may occur. No data are available today on the outgrowth of spice allergy. For yet unknown reasons women have a double risk to develop food allergies including spices.

Diagnosis
Spices are often hidden in the prepared food and not obvious to the consumer. Therefore, a careful recollection of the allergic reactions is the first important step for the diagnosis of this type of allergies. The safest and least invasive procedure for the patient is blood samples, On the other hand, spices may produce false positive results in skin prick or scratch tests through their contents of irritating substances (in particular in pepper, and cayenne.). (For the same reasons skin tests for diagnosis of allergic contact eczema due to spices, may not be sufficiently reliable). Thus, ideally skin tests should be combined with blood samples. Challenges represent a useful tool for the evaluation of the threshold for reactions and for ultimate diagnosis, but has only rarely been applied in spice allergy. Also inhalation challenges with spices have been made, but are infrequent. This is possibly due to the risk for the development of severe side-effects during provocation tests and unfavourable cost assessments.

Avoidance
When diagnosis of spice allergy has been made, absolute avoidance of the spice is recommended. This should include botanically related spices, because they contain similar proteins that with high probability will also act as allergens (see Table 2). Spices are routinely used by cooks in restaurants or private environments in an automated way, and sometimes are handled as kitchen secrets. Therefore, the person in charge of cooking must be advised in advance to prepare the foodstuff on clean dishes without the possibility of contamination with traces of spices. If severe allergic reactions have occurred in the patient before, the recommendations should be even stricter and consumptions in restaurants or of tinned or fast food can no longer be recommended, considering the today's labelling policy.

Labelling of spices was for a long time insufficiently regulated, e.g. was “spice” as a category sufficient for the whole large panel of different ingredients. According to the aim that all ingredients should be labelled regardless of the quantity contained in the finished food, in 2004 a defined list of foods with allergenic potential has been taken up in the EU labelling issues. They are listed in Annex IIIa of Directive 2003/89/EC, to be brought into force by November 25, 2004. Importantly, this list includes celery, mustard and sesame seed which have a well documented allergenic potential. At least for these common spices the option to declare them as ingredients by category will no longer apply. Facing the fact that spices are hidden in foods in low amounts, the new legislation will improve the consumer's situation. However, severe allergic reactions have also been observed to a number of other spices as e.g. poppy (2), coriander, cumin, dill, curry, or saffron. Therefore, complete labelling of spice ingredients should be an ultimate goal.
 
Table 1.

Spices: Synonyms and biological description.
 

Spice	Synonym	Biological Description
Allspice	Jamaica pepper, myrtle pepper, pimento, newspice	Unripe and dried fruits
Anise 1)	aniseed	Dried fruit of annual herb
Basil	tomato herb, herb of kings	annual, spicy herb, fresh or dried leaves
Bay Leaf	sweet bay, laurel	Oval, dark-green, dried leaves
Caraway Seed	Cumin	Dried fruit of a biennial herb
Cardamom	green cardamom, greater c., Nepal c.	Dried, unripened fruit
Cayenne	Chili pepper, red pepper	ripened dried pots
Celery 2)	Celeriac	dried fruit or root of a biennial (sometimes annual) herb
Chervil	Garden chervil, French parsley	small, low-growing annual
Chives	-	reed-like stems of a perennial, bulbous plant
Cinnamon	Indonesian c., Cassia, Vietnamese c. White cinnamon	Dried inner bark of evergreen trees
Cloves		Dried, unopened flavour buds
Coriander	Cilantro, Chinese or Indian parsley Vietnamese coriander or mint	Dried fruits, fresh leaves and roots leaf of annual herb
Cumin seeds	Cumin Black cumin	dried ripe fruit of the annual herb dried ripe fruit of the annual herb
Curry Powder	-	blend of coriander, turmeric, cumin, nutmeg, onion, and other spices
Dill	Dill seed or dill weed	Annual plant: dried fruit or dried leaves.
Fennel	Sweet cumin	Dried ripe fruit of the annual plant
Garlic	-	Bulb (cloves)
Ginger		dried knobby shaped rhizome (but not root) of perennial herb
Mace	Nutmeg flower	scarlet membrane (arillus) enwrapping the shell of the nutmeg
Marjoram	Sweet marjoram, knotted marjoram	Dried leaves and floral parts of herb
Mustard	-	Seeds from annual herb
Nutmeg	-	Dried, aromatic seed (called “nut”)
Onion	Scallion, shallots (young onion)	single-bulbed, biennial, herbaceous plant
Oregano	"Wild Marjoram", oregan	leaf of the plant
Paprika	Bell pepper, pod pepper, sweet pepper	Fruits are used dried and ground
Parsley	-	dried and fresh leaves and roots of biennial plant
Pepper: black, white, green	-	berries of tropical vine, dried or pickled (green pepper)
Pink Pepper-corns	Baies roses, pepper rosé	berries native to the Island of Reunion

1.  Spices with reported allergenicity are underlined.
2.  Spices taken up in the Annex IIIa of Directive 2003/89/EC of the European Community guidelines are underlined and bold.

Table 2. The botanical relationships among important spices.

Botanical family	Spices to be avoided
Apiaceae	Anise 1), caraway seed, celery 2), chervil, coriander, cumin, dill, fennel, parsley
Solanaceae	Cayenne (chilli), paprika
Myrtaceae	Allspice, cloves, mustard
Lamiaceae = Labiatae	Basil, marjoram, oregano, rosemary, sage, savory, thyme
Lauraceaea	Bay leaf, cinnamon
Zingiberaceae	Cardamom, ginger, turmeric
Alliaceae	Chives, garlic, onion
Myristicaceae	Mace, nutmeg
Piperaceae	Black, white, green pepper
Polygonaceae	Vietnamese coriander
Pedaliaceae	Sesame seeds
Canellaceae	White cinnamon
Anacardiaceae	Pink pepper
Papaveraceae	Poppy seeds
Iridicaceae	Saffron
Illiaceae	Star anise
Asteraceae	Tarragon
Orchidaceae	Vanilla

1.  Spices with reported allergenicity are underlined.
2.  Spices taken up in the Annex IIIa of Directive 2003/89/EC of the European Community guidelines are underlined and bold.