Buckwheat is grown almost worldwide, but is especially common in China and Iraq. Its original habitat is obscure. It is a member of the Polygonaceae group of weeds. (Wodehouse 1971 ref.440 34) In China another type of Buckwheat, Tartary Buckwheat (Fagopyrum tartaricum) is grown and consumed. (Wieslander 2001 ref.4302 6). Buckwheat is largely consumed in Asian countries, in particular in Japan, where it is a major food allergen due to the large consumption of Soba (buckwheat noodles).

Buckwheat is a large-leafed, herbaceous species and not a grass, and thus not a true cereal. The only other common food plant in this family is rhubarb. Buckwheat grows to 1.5m at a fast rate. In the Northern Hemisphere, it is in flower from July to September, and the seeds ripen from August to October. The scented flowers are monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and are pollinated by bees and flies. A very good green manure plant, it can be used to reclaim badly degraded soils and sub-soils. There is a variety of cultivars.

Buckwheat is useful as a substitute for wheat and other small grains (rice, barley, oats, rye), in particular as an alternative to people allergic to wheat.

Buckwheat grows in cultivated beds and, where it has escaped from cultivation, on waste ground. Buckwheat ground flour is used for bread and other baked products. The seed is processed to make noodles (termed 'soba' in Japan) and is used in soups, cakes, biscuits, etc. The grain can produce edible sprouts and excellent beer. The leaves can be eaten raw or cooked like spinach. Buckwheat is high in fibre and has high levels of minerals, vitamins and essential amino acids, especially lysine. It also contains rutin, which is believed to improve cardiovascular health by dilating the blood vessels, reducing capillary permeability, and lowering blood pressure.

Buckwheat is used internally in the treatment of high blood pressure, gout, varicose veins, chilblains, radiation damage, etc. It is best used in conjunction with vitamin C, since this aids absorption. Often combined with lime flowers (Tilia species), it is a specific treatment for haemorrhage into the retina. A poultice made from the seeds has been used for restoring the flow of milk in nursing mothers. An infusion of the herb has been a treatment of erysipelas (an acute infectious skin disease). A homeopathic remedy has been made from the leaves and used in the treatment of eczema and liver disorders.

The hulls of buckwheat are used as cushion fillings in some Asian countries. A blue dye is obtained from the stems, while a brown dye is obtained from the flowers.

Buckwheat dust is round in shape and varies from 1 - 7 um/L, which can easily penetrate dust mite encasings which usually have a pore size of 10 um/L. (Fritz 2003 ref.7756 5)

Allergens/Function:

Allergens:
Fag e 1, a legumin, an 11S Globulin-like protein.

Very potent allergen causing both food and inhalent allergy. A 14 and 18 kDa in size and found to share some homology with rice proteins associated with rice allergies and cross-allergenicity with buckwheat proteins. Both are major allergens. (Yoshimasu 2000 ref.3875 1)

A 24 kDa protein was shown to be the most frequently recognized allergen, binding to IgE antibodies from 100% of the patients' sera. (Kondo 1993 ref.1336 3)

Approximately 30% of total buckwheat proteins are 2S albumins. These polypeptides range from 8 to 16 kDa, and are water soluble. (Radovic 1999 ref.7489 3) (The allergenicity of this these proteins were not tested for. Ed.)

In 19 buckwheat-allergic subjects with symptoms after buckwheat ingestion with positive skin prick tests to buckwheat, proteins of 24, 19, 16, and 9 kDa were isolated and reported to be strong candidates to be major allergens. The 19-kDa allergen was relatively specific for buckwheat-allergic patients. IgE binding to the 24, 16, and 9 kDa allergens was higher than 50% in buckwheat-allergic subjects. The specific IgE to split 19 kDa allergens were more specifically found in buckwheat allergic patients than in positive skin prick test asymptomatic subjects (78% vs 7%). The amino-acid sequences of the 19 and 16 kDa allergens showed moderate and weak homology to the 19-kDa globulin protein of rice and alpha-amylase/trypsin inhibitor of millet, respectively. The 9-kDa isoallergens were not different from each other and were identified as trypsin inhibitors. (Park 2000 ref.3876 3)

Allergens are glycoproteins. One of the proteins is a trypsin inhibitor. (Yano 1989 ref.443 38)

A 24 kDa globulin protein has been identified as a major allergen. (Wieslander 2001 ref.4302 3)

We found that the 24-kD protein that had previously been reported to be a major allergen reacted to IgE antibodies present in sera from almost all subjects (19/20) regardless of symptoms. On the other hand, 16- and 19-kD proteins were bound with IgE antibodies present in sera from 9 of the 10 patients with IHR including 8 patients with anaphylaxis but not in sera from buckwheat-specific IgE-positive subjects without immediate hypersensitivity reactions. After pepsin treatment, the 16-kD protein but not the 19- and 24-kD proteins remained undigested and preserved the capacity of IgE binding. The 16 kDa buckwheat protein is resistant to pepsin digestion and appears to be responsible for Immediate Hypersensitivity Reactions (IHR) including anaphylaxis, while the pepsin-sensitive 24-kD protein was responsible for CAP-FEIA but not IHR. (Tanaka 2002 ref.6975 3)

Buckwheat seed contains a thiamin-binding protein. (Watanabe 1998 ref.7449 4) The clinical relevance of this protein is unknown. Ed.

The analysis of buckwheat-specific IgE antibody in an 8 year old with fatal food-dependent exercise-induced anaphylaxis, 7 protein bands that reacted with the IgE of the patient's serum was demonstrated, 4 bands: 16, 20, 24, and 58 kDa, were specific to the patient as compared to subjects not allergic to buckwheat. (Noma 2001 ref.6693 2)

Buckwheat seeds contain a proteinaceous inhibitor of trypsin and chymotrypsin. (Pokrovskii 1989 ref.7496 2) The clinical significance of this protein was not determined.

Adverse Reactions:

IGE AND IMMUNE:
Positive skin tests to buckwheat are found in about 5% of Koreans. (Sohn 2003 ref.8664 3)

Allergic rhinoconjunctivitis, asthma, urticaria, angiodema and anaphylaxis have been reported. Buckwheat allergy is reported to be rare in the USA but it is not uncommon in Japan and other Asian countries where buckwheat consumption is more widespread. (Fritz 2003 ref.7756 5)

Immediate hypersensitive reactions induced by buckwheat ingestion are considered to be IgE-mediated. Some subjects, however, develop no immediate adverse reactions after buckwheat ingestion despite high levels of buckwheat-specific antigens IgE. The mechanism is unknown. (Yamada 1995 ref.99 485)

Repetitive emesis and angiodema in a man. (Smith 1909 ref.8127 3) (Smith 1990 ref.7494 6)

In 34 children with atopic dermatitis, 33 were SPT positive with wheat and 18 with oats. Positive RAST to wheat and oats could be detected in 32 and 30 samples respectively. SPT with rice, corn, millet or buckwheat was positive in 16/34 patients (Varjonen 1995 ref.1295 1)

Hypersensitivity to buckwheat allergen frequently causes anaphylactic type reactions including urticaria, wheezing, dyspnea and/or shock. Results of a questionnaire send to 341 elementary school nurses in Yokohama, of 92,680 children, the incidence of buckwheat allergy was determined to be 0.22% (140 boys and 54 girls). Symptoms were urticaria (37.3%), skin itching (33.3%), and wheezing (26.5%). Anaphylaxis was reported in 4 children (3.9%). The incidence of anaphylaxis due to buckwheat was higher than those due to egg and milk allergy. Seven pupils had allergic reactions to buckwheat noodle served at school lunch. (Takhashi 1998 ref.2518 1)

Can cause severe allergic reactions much more severe than wheat and it's relatives. GIT symptoms, urticaria, angioedema, dyspnoea, wheezing, asthma, rhinitis, anaphylaxis and shock. (Davidson 1992 ref.442 38) (Blumstein 1935 ref.441 32) Throat itching and pain. Contact urticaria.

Urticaria, quincke edema and asthma. (Schumacher 1993 ref.1348 3)

Nocturnal asthma from sleeping on buckwheat chaff-stuffed pillows (a common pillow filling in Korea), as a result of buckwheat allergy. (Lee 2001 ref.4300 5) (Matssumura 1969 ref.7503 3)

Pulmonary haemosiderosis related to non-immediate buckwheat protein hypersensitivity. The patient had no serum or skin specific IgE, but was positive to a patch test. (Agata 1997 ref.612 34)

D. farinae, an important allergenic substance in buckwheat-husk pillows. (Hong 1987 ref.188 65)

Wheatburger anaphylaxis due to hidden buckwheat. (Wuthrich 1995 ref.2450 6)

This study demonstrated a 20% reduction in lung function to inhalation of aerosolised fish, buckwheat and chick pea. (Golder 2000 ref.3544 3)

12 children with an IgE-mediated food allergy who developed asthma on inhalational exposure to food were identified. The implicated foods were fish, chickpea, milk, egg or buckwheat. Nine out of the 12 children consented to undergo a bronchial food challenge. Five challenges were positive with objective clinical features of asthma. Additionally, two children developed late-phase symptoms with a decrease in lung function. Positive reactions were seen with fish, chickpea and buckwheat. (Roberts 2002 ref.6660 1)

An 8-year old girl with food-dependent exercise-induced anaphylaxis caused by Japanese buckwheat. The patient consumed buckwheat noodles called "zaru soba" and immediately thereafter swam vigorously. Approximately 30 minutes later, she complained of abdominal pain, vomiting, coughing, and chest discomfort. Another ten minutes later her consciousness level deteriorated and she experienced cardiorespiratory arrest. An exaggerated hematemesis that occurred immediately after hospital admission indicated an inflammatory condition of the digestive tract that was caused by buckwheat. Marked ulceration accompanied with hemorrhage and necrosis was noted at the ileum. Extensive hemorrhage involving the endotracheal pulmonary field and lymphocyte infiltration of the alveolar space likely appeared after the inflammation. Serum specific IgE was raised for buckwheat. (Noma 2001 ref.6693 2)

Anaphylactic reaction in a 19-year-old-man after eating 'poffertjes' (small Dutch pancakes), the principal ingredient being buckwheat. It is highly likely that the patient was sensitised by sleeping on a pillow stuffed with buckwheat husk. (van Ginkel 2002 ref.7485 2)

Anaphylaxis. (Schiffner 2001 ref.7462 1) (Leynadier 2001 ref.7487 1)

Some subjects with high IgE for buckwheat show no immediate hypersensitive reactions to buckwheat ingestion. (Wada 1991 ref.7570 2)

A report of a person who developed asthma and worsening allergic rhinitis after exposure to a buckwheat pillow. The patient showed a 4+ skin prick test response to buckwheat. His ImmunoCAP test for buckwheat-specific IgE was class 4, or strongly positive. (Fritz 2003 ref.7756 5)

Buckwheat flour is a potent food allergen. Sensitization usually occurs by ingestion, but also by inhalation in occupational or domestic situations. During the course of their manufacture, pillows stuffed with buckwheat husks may be contaminated with buckwheat flour and thus constitute a cause of nocturnal asthma in buckwheat-sensitized individuals. (Mairesse 2003 ref.8643 3)

Buckwheat allergy in a child. (Bourrier 2003 ref.8644 4)

Cross-reactive.

OCCUPATIONAL EXPOSURE:
Animal workers, baker & bakery, food industry, mill workers

Occupational allergen - Rhinitis, conjunctivitis, asthma, itch or urticaria occurred to exposure of comparatively low levels of buckwheat dust in connection with the grinding and packaging of buckwheat (Gohte 1983 ref.235 75) (Valdivieso 1989 ref.3066 2), to buckwheat flour (Obase 2000 ref.7488 2), and in a noodle maker. (Park 1996 ref.2449 3)

Occupational exposure to buckwheat flour has been associated with rhinitis, conjunctivitis, contact urticaria, and occupational asthma. We present a patient who developed urticaria and hypotension after ingestion of buckwheat crepes. (Davidson 1992 ref.442 12)

Occupational asthma in an individual working in pancake restaurant. Confirmed was obtained by specific bronchial challenge with aerolised buckwheat. (Choudat 1997 ref.2448 2)

Occupational allergen (Wieslander 2001 ref.4302 6)

NON IMMUNE:
Unknown or Nil