Route Of Exposure

Allergen Exposure

Probably native to southern Europe or Asia Minor, Coriander was cultivated in ancient China, Egypt, Greece and Rome for culinary and medicinal uses, and is one of the oldest spices on record. It was used as early as 5000 years ago and is mentioned frequently in the Bible. Today, Coriander is grown almost throughout the world (including in Peru, Egypt, Africa, North America, India, the former Soviet Union, Southern and Central Europe, Morocco, and South and Western Australia). It is useful for its fresh green leaves (Cilantro, Culantro or Long Coriander: clean, sharp flavour, somewhat reminiscent of Mint) and its dried yellowish, round, ribbed or spiked “seed” (actually the fruit or pod; Coriander: strong, aromatic, slightly bitter). This makes Coriander both an herb and a spice. The root is used only in Thailand.

Coriander is an erect annual (the height can reach over a metre) with delicate fernlike foliage and pinkish-white flowers in flat clusters. The plant’s leaves have 2 different shapes: the base leaves are broad and pinnate, a little like those of Italian Parsley The upper leaves are the ones described as fernlike

The seeds and the leaves are used both crushed and whole. The dried seeds are "Coriander". They are familiar as a seasoning in European and Middle Eastern meats, beans, sausages, marinades, stews, breads, cakes, cookies (particularly gingerbread), wines, gin and liqueurs. Coriander is an essential part of curry powder (which may additionally contain Nutmeg, Black and White Pepper, turmeric, Clove, Ginger, Cinnamon, Cardamom, Mustard, cayenne, Caraway and other spices and Indian masalas. Other common spice blends, both in the East and West, contain Coriander. Coriander seeds are used in perfumery and to disguise the taste of medicines. The seeds are also sometimes coated with sugar and eaten as sweets.

The young leaves are popular in most of southern Asia, and their use has spread geographically along with these cuisines. They are almost always used fresh, as the flavour of the dried leaves is lost. They appear very often in salads, poultry dishes and soups. They are indispensable in Thailand (for green curry paste both the root and the leaves are needed), and in Vietnam and parts of China, where the chopped leaves are decorations on nearly every dish. In Thailand the roots are grated and used as a condiment. A famous Mexican food relying on Coriander leaves is guacamole.

The stronger, European variety of ripe Coriander fruits contains up to 1.8% essential oil, which consists mainly of linalool (50 to 60%) Coriander oil is used to flavour alcoholic beverages, candies, meat, sauces and tobacco. Both the fruits and oil are used to correct the nauseating or griping qualities of medicines. The oil is also important in the perfume industry.

The spice has been used, inter alia, to treat digestive and joint complaints, and allergy and hay fever, and to stimulate the appetite.

Clinical Relevance

Allergen decription

No allergens from this plant have yet been characterised.

A 11 kDa allergen has been detected.

Two IgE-reactive protein bands from Coriander extract of 50 and 56 kDa were found in a patient with occupational asthma to Coriander.

Clinical observations indicate that Mugwort and Birch pollen allergy, and hypersensitivity to spices (Apiaceae: Anise, Fennel, Coriander and cumin) are frequently associated. In sera of 15 patients who experienced adverse reactions to spiced food, the presence of cross-reacting allergens was demonstrated through immunoblot and inhibition experiments, and a relationship was shown to Bet v 1 or Bet v 2 (a profilin). Cross-reacting allergenic molecules of a molecular weight around 60 kDa were detected. IgE binding to spice allergens occurred only with sera of 10/15 (66%) patients with allergy to pollen (Birch, Mugwort) and/or celeriac. In 5 out of 15 (33%) patients with a history of adverse reaction to spices, but without pollen and celeriac allergy, no IgE-binding to any spice protein could be demonstrated. The authors suggested that it was possible that these clinical reactions could be elicited by other types of hypersensitivity (Type II, III, IV), but as spices contain highly reactive substances, the symptoms may most likely be classified as due to food intolerance.

Potential Cross Reactivity

An extensive cross-reactivity among the different individual species of the genus could be expected, and laboratory findings suggest that the botanically related spices Coriander, Anise and Dill contain common IgE-binding structures.

Accordingly, in a patient with occupational allergy to Anise seed, skin-specific IgE tests to Apiaceae family members showed a positive immediate response to Anise, Asparagus, Caraway, Coriander, cumin, Dill, and Fennel extracts. Caraway, Fennel, cumin, and Coriander extracts showed similar IgE-binding patterns. Enzyme immunoassay inhibition studies with the patient's serum revealed cross-reactivity among the IgE components from Aniseed, Caraway, Coriander, Fennel, and Dill extracts.

Cross-reactivity has also been reported between Mugwort and Birch pollen.

Clinical Experience

IgE-mediated reactions

Coriander may occasionally induce symptoms of food or skin allergy in sensitised individuals.

According to the CICBAA data bank in France, in skin-specific IgE tests for spice carried out in 589 patients with food allergy and suspected food allergy to spices, frequent sensitisation to Apiaceae were observed: Coriander, Caraway, Fennel and Celery.

Nevertheless, food allergy to spices was infrequent: 2% of all food allergies. Serum-specific IgE to Coriander and/or Curry, Mace, Celery, and White Pepper was measured in 150 sera from patients with suspected food allergies.

As Coriander is frequently a component of spice blends, it may be that allergic reactions occur to Coriander but are not attributed to this spice. In reporting on a study documenting the experience of urticaria, angioedema or anaphylaxis occurring after meals in Chinese or Indonesian restaurants, the authors maintain that these symptoms are more often due to IgE-mediated Type I food allergy, caused by consumption of Shrimp, Peanut or spices, in particular those of the Parsley family (e.g., Coriander), than to MSG.

Unexpected Coriander culpability is supported by other reports: a 42-year-old woman developed anaphylaxis after a meal. Skin-specific IgE tests were positive for Coriander and Curry. Serum-specific IgE was positive for a number of spices including Coriander. The allergen responsible did not appear to be a 2S albumin, an allergen common in seeds. Similarly, a 14-year-old girl developed anaphylactic symptoms on 2 occasions following a meal made with teriyaki sauce. She experienced difficulty breathing and a sensation of throat swelling and generalised urticaria. Wheezing was documented. Skin-specific IgE tests were positive to teriyaki sauce, and to the ingredient Coriander. Oral challenge with Coriander was positive, resulting in additional symptoms of rhinorrhoea and itching of the neck.

Coriander, like other spices, results in allergic skin manifestations, including contact urticaria, more commonly than other allergic reactions. Allergic contact dermatitis, in particular of the hands, has been reported. Skin-specific IgE tests with common spices performed in 1,120 atopic and 380 non-atopic patients showed that skin-specific IgE was almost exclusively found in atopic patients. Curry and Paprika produced reactions most frequently. When the components of curry were tested separately, Coriander, Caraway, Cayenne and Mustard were responsible for the vast majority of the positive reactions.

A study reported that skin-specific IgE tests with commercial powdered spices are commonly positive in patients with allergy to Birch or Mugwort pollen. An evaluation of skin-specific IgE tests with Coriander, Caraway, Paprika, cayenne, Mustard, and White Pepper, done twice at 2-month to 2.9-year intervals in 49 patients, demonstrated that all the spice extracts, except for White Pepper, elicited positive reactions in half those with positive reactions to native spices. Three-fourths of the patients with positive skin tests to native spices were positive to Birch pollen, and half to a vegetable. Mild clinical symptoms from spices were reported by a third. Fourteen out of 21 patients with positive reactions to Coriander were also positive to Cayenne.

Similarly, in a study with skin-specific IgE tests for powdered commercial spices performed on 70 patients with positive skin-specific IgE tests to Birch and/or Mugwort pollen and Celery, positive results were demonstrated in more than 24 patients to Aniseed, Fennel, Coriander and Cumin - all members of the same botanical family as Celery, Apiaceae.

Although the studies have concentrated on immediate-type reactions, delayed-type hypersensitivity mechanisms may occur, as shown by patch tests.

Occupational allergy to Coriander may occur in individuals working in the food industry, and in liqueur and spirit manufacturers. After 3 years of occupational exposure to powdered Coriander in a factory, packing spice, a woman developed symptoms of immediate hypersensitivity with respiratory symptoms to Coriander. She complained of rhinitis and irritation of the throat. Skin- and serum-specific IgE tests and nasal and bronchial challenge tests were positive.

Occupational asthma was described in a 27-year-old who developed rhinitis and asthma symptoms 1 year after starting to prepare a particular kind of sausage. Positive skin-specific IgE for Paprika, Coriander, and Mace were demonstrated, but absent for other common sausage ingredients: mites, pollens, and molds. Serum-specific IgE antibodies to Paprika, Coriander, and Mace were demonstrated. Immunoblot analysis showed the presence of 50 and 56 kDa allergenic proteins from the Coriander extract. Specific bronchial inhalation challenges showed an immediate asthmatic reaction to extracts from Paprika, Coriander, and Mace. The authors point out that in this patient, occupational asthma was due to spices from botanically unrelated species.

Occupational protein contact dermatitis to Coriander, Carrot and Potato was reported in a 22-year-old chef, who had developed pruritic hand dermatitis from handling raw Potatoes, Tomatoes, Carrots, and Curry. Dermatitis developed on his face if juice of these vegetables splashed on it.

Occupational asthma and rhinitis to licorice (dust), Mace, Aniseed, Coriander and iris root in was reported in an Anise liqueur factory worker.

Occupational asthma to dust from spices was described in a 26-year-old man working with spices in the food industry. Skin-specific IgE tests with Curry, Coriander, and Mace were strongly positive. Serum-specific IgE antibodies against Coriander, Curry, Mace, Ginger, and Paprika powder could be demonstrated. No cross-reactivity between Coriander and Ginger or Paprika could be demonstrated.

Other reactions

Coriandrin, a furoisocoumarin, occurs naturally in Coriander and has very weak skin photosensitising activity as compared with psoralen.

Coriander leaves may be contaminated with bacteria. An outbreak of restaurant-associated salmonella infection in California in 1999 was described. Three patients were hospitalised. An association was found between illness and eating Cilantro at a restaurant. At room temperature, Salmonella Thompson grew more rapidly and to a higher concentration on chopped Cilantro, compared with whole-leaf Cilantro. Freshly made salsa (pH 3.4) supported growth of Salmonella Thompson. The authors concluded that Cilantro should be served promptly after chopping.

Anecdotal reports claim that excess intake of the seed may have narcotic effects.