Buckwheat Allergy and Buckwheat Consumption in Taiyuan City

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					                                                      The proceeding of the 8 11'ISB:613-619(2001)

Buckwheat Allergy and Buckwheat Consumption in Taiyuan City, Northern China

       Dan NORBACK, Gunilla WIESLANDER, Zuan Hua WANG1), Zheng Zhang 2),
                           Yahong MI, and Rufa L1N 2)
          Department of Medical Science, Uppsala University, Uppsala, SWEDEN
            'Department of Life Science, Shanxi University, Taiyuan, CHINA
               2)Shanxi Academy of Agricultural Sciences, Taiyuan, CHINA


  In China, both common buckwheat (Fagopyrum esculentum) and tartary buckwheat
(Fagopyrum tartaricum) are consumed. The aim was to study buckwheat allergy and other
hypersensitivity in selected groups in Taiyuan city, Shanxi, a buckwheat growing province in
northern China. Eighteen researchers with occupational exposure to buckwheat, twenty five
workers in a buckwheat noodle factory, and twenty six patients consuming buckwheat as
functional food were invited to the investigation. Skin prick test was performed by a
standardised buckwheat allergen extract on 61 participants (88%), 34 males and 27 females. In
total, 34% consumed buckwheat food at least every week, and 23% had a weekly consumption
of tartary buckwheat. One male industrial worker had a positive skin prick test to buckwheat,
but no symptoms while eating or handling buckwheat products. Two other subjects with
negative skin prick test to buckwheat reported stomach pain and skin rashes, respectively,
while consuming buckwheat of both types. In conclusion, weekly consumption of both types
of buckwheat was common. Buckwheat allergy was rare but there were some indications of
non-specific food intolerance to buckwheat. The prevalence of doctors' diagnosed asthma and
allergic disorders was low as compared to Western Countries, but similar as in other studies in
Chinese population.
  Key words:allergic rhinitis, asthma, atopy, buckwheat allergy, Fagopyrum tartaricum,
              Fagopyrum esculentum, food allergy, China


  Buckwheat, with a protein content higher than in rice, wheat and sorghum, is an important
crop in some regions of the world (1). Common buckwheat (Fagopyrum esculentum) is grown
in Asian countries e.g. China, Japan, Korea, Nepal and Bhutan (2). Tartary buckwheat
(Fagopyrum tartaricum) is another species, grown in some parts of China (3, 4). There is a
growing interest in buckwheat as a health promoting food (functional food) (5). Since
buckwheat can be used to produce a gluten free flour, it is consumed by many subjects with
gluten sensitive enteropathy (celiac disease)(6). There are some publications available on food
allergy in China (7-9) , but none of these has studied buckwheat allergy.
  Buckwheat allergy is an IgE mediated immediate type reaction, sometimes causing severe
reactions similar as for soybean and peanut allergy (10). The allergic reaction can occur when
eating buckwheat food (II), at occupational exposure (12), or at domestic exposure when
sleeping on a pillow stuffed with buckwheat husk (13, 14). Cases of occupational buckwheat

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asthma has been reported from noodle shops in Japan (15), Korea (16), Spain (17), and France
(18). In Sweden, 46% of 28 workers repackaging health food products got symptoms (asthma,
rhinitis, skin eruptions) when handling buckwheat and 28% had buckwheat allergy (12).
  The aim of the present study was to investigate buckwheat allergy, as well as other types of
hypersensitivity, in three groups in the Shanxi province in China. They had either occupational
exposure to buckwheat, or a high consumption of both tartary and common buckwheat food

                               MATERIALS AND METHODS

  This study was performed in the city of Taiyuan, the main city ( 2.2 million inhabitants) in
Shanxi province, west of Beijing. The area is a centre for coal mining in China, but has also a
tradition of growing and consuming both tartary and common buckwheat. Three groups were
selected for the study, exposed to both types of buckwheat. The first group consisted of 18
researchers in agriculture, botany and biochemistry handling buckwheat in their work, 16
participated (90%). The second group consisted of 25 workers in a food factory in Taiyuan,
producing buckwheat food, including buckwheat noodles, all participated (100%). The third
group consisted of patients belonging to a patient society for people with diabetes and
cardiovascular disease. They consumed buckwheat food regularly, recommended by their
doctors, to alleviate their disease. Twenty-six patients were invited and 20 participated (77%).
  A standardised questionnaire translated to Chinese (mandarin) was answered by the
participants before the skin prick test. Information was gathered on occupation, age, gender,
smoking, atopic disposition, asthma, allergic rhinitis, food intolerance of different type, and
medical symptoms in relation common and tartary buckwheat, respectively. In addition,
information was gathered on the frequency of consumption of buckwheat food, and frequency
of occupational contact to buckwheat products. Buckwheat consumption, as well as
occupational exposure to the two types of buckwheat, was described as "never", "a few times a
year", "every month" and "every week".
  Skin prick tests were performed by a standardised allergen extract from buckwheat
manufactured by ALK laboratories Inc. (Solu-Prick ALK Laboratories, California), on the
volar aspect of the forearm, using a lancet from ALK. Histamine was used as a positive
control. Sensitisation to buckwheat was indicated by a positive skin prick test, defined as a
means a wheal diameter of =/> 3 mm. A negative control with normal saline was used, and its
diameter was subtracted from the diameter of the allergen solution. In addition, we performed
a gel-electrophoresic analysis of the buckwheat extract, which confirmed that it contained the
24 kD protein, only.


  The mean age was 41 years (SD=9) in the researchers, 34 year (SD=ll) in the food factory
workers), 60 years (SD=12) in the patient group, and 45 years (SD=15) in the total material of
61 participants. The mean proportion of females was 44%, with a majority of males in
researchers and patients, and a majority of females in factory workers (Table 1).

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Table 1. Demographic and medical data for the three studied groups exposed to buckwheat, and the
total material.
                                          Researchers      Workers           Patients      Total
                                          (N=16)(%)        (N=25)(%)         (N=20)(%)     (N=61)(%)
 R~e                                      ~                W                 ~             44
 Current smoker                          50                 8                 15           21
 Doctor's diagnosed asthma                 0                4.0                0            1.6
 A history of atopy                       19               13                 15           15
 Allergic rhinitis                         6.3               13                0            6.8
 Childhood eczema                         13                  0               15            8.5
Buckwheat allergy"                         0                  4.2             01.6
"A positive skin prick test to buckwheat allergenic extract, and a negative test to NaCl

  Consumption of buckwheat food products was common, 34% of all participants consumption
any type of buckwheat at least once a week. The consumption of both types of buckwheat was
commOn (Table 2).

Table 2. Reported food consumption of tartary and common buckwheat, in the total material of 61
                                        Tartary               Common              Any type
                                        buckwheat             buckwheat           of buckwheat
  Frequency of consumption              (%)                   (%)                 (%)
  Every week                            23                    16                  31
  Every month                           23                    24                  23
  Every year                            45                    50                  41
  Never                                 9                     10                  0
Five subjects did not answer the question on specific consumption of tartary buckwheat, three subjects
did not answer the question on specific consumption of common buckwheat, but all gave information
about buckwheat consumption in general (irrespective of the type)

  Occupational exposure to buckwheat, in researchers and food factory workers (N=41), was a
mixed exposure to both tartary and common buckwheat. In total, 45% had a weekly exposure
to buckwheat of any type, and 58% had occupational exposed to buckwheat at least once a
month. The mean occupational exposure time to buckwheat was 10 years (SO=7) for
researchers, and 5 years (SO=9) for factory workers.

                          ADVERSE REACTIONS TO BUCKWHEAT

  One of the industrial workers had a positive skin prick test to buckwheat extract (Table 1),
with a mean diameter of 5 mm for the buckwheat extract, 9 mm for histamine, and 0 mm for
normal saline. He was a packaging worker, not directly involved in the production. He was a
smoker without asthma or atopy, consuming common buckwheat each month and tartary
buckwheat every week. He had nO symptoms while or after eating buckwheat products, and
experienced nO symptoms in relation to occupational exposure to buckwheat. Another female
office worker at the noodle factory, had slight and similar reaction (2 mm mean diameter) to
both normal saline solution and the buckwheat allergenic extract, and a 9 mm diameter

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reaction to histamine. The reaction was classified as dermographism. She experienced no
adverse reactions when eating tartary or common buckwheat, which she consumed a few times
a year.
  Two other subjects with negative skin prick test to the buckwheat extract reported adverse
reactions of non-allergic type (food intolerance) when consuming both types of buckwheat.
One was a male researcher who experienced stomach pain when eating buckwheat. He was a
smoker, without asthma or a history of atopy, and consumed buckwheat a few times a year. He
had worked as buckwheat researcher the latest 15 years, and was handling buckwheat at work
every week. The other was a non-smoking male in the patient group, who got skin rashes when
eating buckwheat, which he consumed a few times a year. He had a history of childhood
eczema, but no asthma or atopic rhinitis.


  In total, four subjects (6.6%) reported immediate type allergy to pollen, with atopic rhinitis,
none reported allergy to furry animals. And another five subjects (4.9%) reported a history of
childhood eczema, and one had doctors' diagnosed asthma (1.6%) (Table 1). The female
factory worker, with physician diagnosed asthma was treated with asthma medicine. She had a
history of atopy, reporting allergic reactions, including rhinitis, to pollen from cedar, carnation,
and peach. Two other non-smoking female workers also reported tree pollen allergy and one
old female researcher with atopic rhinitis reported allergy to carnation, and peach. One subject
reported food intolerance, with stomach pain while eating mutton.


  Consumption and occupation exposure to both common buckwheat and tartary buckwheat
were common, but the occurrence of buckwheat allergy was low. None in the occupationally
exposed groups reported any work-related reaction to buckwheat, neither to common
buckwheat nor tartary buckwheat. Two got adverse reactions at consumption of buckwheat of
both types, stomach pain and eczema, respectively. One factory worker had buckwheat allergy,
indicated by positive skin prick test to buckwheat extract, but no symptoms. He will be
followed to see if he will develop symptoms. The buckwheat extract was prepared by an
American pharmaceutical company (ALK), and gel electrophoresis have verified that it
consists of a 24 kDa protein (3), a protein similar to one of the proposed main allergens in
buckwheat (19,20).
  There is a lack of information on the prevalence of buckwheat allergy in the population of
most countries, except from Japan. In the sixties, Nakamura and Yamaguchi (1974/1975)
identified 169 cases of buckwheat allergy in a nation-wide survey of hospital patients (21).
  The most common reaction was buckwheat asthma (82%), and in 18 cases, (11 %)
anaphylactic shock had occurred. The largest study on buckwheat allergy was performed in
92680 school children in Yokohama, in the 90'ies (22). In total, 140 boys and 54 girls (0.22%
of all children), had buckwheat allergy. The most common reactions among sensitised children
were urticaria (37.3%), wheezing (26.5%), and anaphylactic shock (3.9%).
  In our previous study in Swedish food packing workers (N=28), a high proportion (28%) had
a positive allergy test to buckwheat, and 46% had any type of symptom in relation to handling

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of buckwheat grains or flour (12).
  In total, three subjects (4.9%) reported any type of adverse reactions to food. Such reactions
need not to be allergy, but may depend on other mechanisms (food intolerance) (23). One got
urticaria when eating both types of buckwheat, one got stomach pain from buckwheat of both
types, and the third subject got stomach pain when eating mutton. In one case study from
Beijing, intracutanous skin tests were performed in 40 cases of subjects with recurrent attacks
of asthma after ingestion of food. The most common positive skin tests were seen for sesame
seed, peanut, cow's milk, soybean, and egg. There were also positive skin reactions to peach
and mutton, but no allergy to buckwheat was reported (9). In one study in 10,144 subjects
from the Sheng-Li Oil fields in Manchuria, in northern China, a similar figure of self-reported
food allergy (4.98%) was found (8). In a subsequent study from a population sample of 6,563
Chinese people, the prevalence of food allergy was 3.41 % (7). For comparison, in a Swedish
study in a random sample of 2,239 school teachers, and 2,410 school pupils, 11 % of school
personnel and 8% of pupils (7-17 years) reported any type of adverse reactions to food. None
of these Swedish subjects reported food intolerance to buckwheat or buckwheat products (24).
  In total, 6.6% in our study reported allergy to cedar pollen, carnation, and peach with atopic
rhinitis. None reported allergy to furry animals, and 1.6% had doctors' diagnosed asthma.
Allergy to cedar pollen is a well recognised problem in Japan (25). Positive skin prick tests to
carnation (Dianthus caryophyllus), and positive nasal provocation tests with carnation extracts,
has recently been described in employees working with indoor cultivation of carnation (26).
Peach allergy has also been described, described to be more common in those with pollen
allergy (27). The highest prevalence of asthma and atopic rhinitis was found in the factory
workers, 4.0% and 12%, respectively. In the study from the Sheng-Li Oil fields in Manchuria,
in northern China, the prevalence was 6.32% for allergic rhinitis and 3.84% for asthma (8).
These are lower figures than the prevalence of asthma and atopy reported from subsequent
large studies from Western countries, e.g. those performed within the world-wide European
Community Respiratory Health Survey (28, 29).
  In conclusion, consumption and occupational exposure to both common and tartary
buckwheat were common in our study from Shanxi province in northern China. The
occurrence of buckwheat allergy was low, but there were indications of non-specific food
intolerance to buck wheat food in some subjects. The prevalence of reported asthma and atopic
disorders was low as compared to subsequent data from Western countries, but similar as in
some other studies from Chinese population.

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