Foxtail millet

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Code: f56
Latin name: Setaria italica
Source material: Peeled seeds
Family: Poaceae (Gramineae)
Common names: Foxtail millet, Italian millet, German millet, Hungarian millet, Siberian millet

Allergen Exposure

Geographical distribution

The name Millet is used to describe seeds from several taxonomically divergent species of grass. They are grown mostly in marginal areas and under agricultural conditions in which major cereals fail to give sustainable yields (1).

See common background for Millets.

Foxtail millet and the other Millets are not closely related to Wheat.

Foxtail millet is used mainly in animal fodder and for bird seed. The main production area is China, but this is the most important Millet in Japan and is widely cultivated in India. Because of its fast maturation, it is a suitable crop for growing by nomads. The height of the plants varies from 1 to 1.5 m, and the colour of the grain varies from pale yellow through orange, red, brown and black (1).

Environment

See common background for Millets.

The Millets are important sources of food for humans and animals. But in the West, with the exception of natural food stores, Millet is sold mainly as bird feed.

Unexpected exposure

See common background for Millets.

Allergens

No allergens from this plant have yet been characterised.

A number of proteins have been isolated and described as occurring in Foxtail millet. The allergenic potential of these proteins was, however, not evaluated.

Barnyard millet, Common millet, Little millet, Foxtail millet and Kodo millet were studied. The protein contents of the selected decorticated Millets were found to be 11.0, 12.3, 12.9, 10.5 and 10.6%, respectively. Prolamin is a major storage protein in Foxtail millet, whereas glutelin is a major storage protein in all the other Millets. A protein band at the molecular weight range of 20 kDa was found to be homologous in all except Proso millet (2).

A Foxtail millet glutelin of 60 kDa (MG60) has been isolated. The primary structure at the N-terminal end was almost identical to those of the granule-bound starch synthase (GBSS) proteins from Rice, Barley, Maize, Wheat and Potato. Common epitopes from these starch-storing cereals were corroborated by immunoblot analysis, strongly suggesting a close relationship (3).

In a study, the antigenic relationships among "minor Millets" (Barnyard, Little and Foxtail millets) and other cereals (Wheat, Maize, Rice, Sorghum, Finger millet and Pearl millet) were evaluated using an antibody raised against a 20 kDa prolamin from Kodo millet. It was demonstrated that the prolamin was related to the prolamins from the other plants. Rice was the only common cereal that did not cross-react immunologically with the 20 kDa prolamin of Kodo millet (4).

A subtilisin inhibitor has been isolated from seeds of Foxtail millet (5).

Proteinase inhibitors (trypsin/chymo-trypsin) have been demonstrated to be present in Finger millet, Sorghum, Pearl millet, Foxtail millet, and Japanese millet (6). The amino acid sequence of an isolated trypsin inhibitor (7) had a high degree of homology to Bowman-Birk type inhibitors from leguminous and gramineous plants (8).

Cross-allergenicity among Rice, Wheat, Maize, Japanese and Foxtail millet was examined by IgE antibody determination and RAST inhibition studies, demonstrating significant close correlations among the 5 cereal grain extracts. A Rice protein of16 KDa was shown to be one of major allergens in Rice grain extracts (9-10). The protein showed sequence homology to Wheat alpha-amylase inhibitor and Barley trypsin inhibitor (11). The clinical relevance of this protein was not assessed.

Potential cross-reactivity

A Rice protein of 16 kDa has been shown to be involved in cross-allergenicity among antigens in Rice, Wheat, Maize, Japanese millet and Foxtail millet (10). The clinical relevance of this allergen was not examined.

In a study, the antigenic relationships among "minor Millets" (Barnyard, Little and Foxtail millets) and other cereals (Wheat, Maize, Rice, Sorghum, Finger millet and Pearl millet) were evaluated using an antibody raised against a 20 kDa prolamin from Kodo millet. It was demonstrated that the prolamin was related to the prolamins from the other plants. Rice was the only common cereal that did not cross-react immunologically with the 20 kDa prolamin of Kodo millet (4). The clinical significance of this was not evaluated.

Clinical Experience

IgE-mediated reactions

Hypersensitivity to cereals may occur via inhalation or ingestion, but reported allergy to Foxtail millet is rare.

With the increasing popularity of "natural foods", Millet is more frequently included in various dishes, which might raise the incidence of Millet-related allergic reactions. Patients with adverse reaction to Gluten may substitute Millet for gluten-containing cereals.

Little information is available on the allergens causing symptoms in patients with atopic dermatitis. One study analysed the IgE immune response to various cereals and to specific protein fractions of Wheat and Oats in children with severe atopic dermatitis (AD) and correlated the results with challenge studies. In SPT studies, 33 children were positive for Wheat and 18 for Oats. SPT for Rice, Maize, Millet or Buckwheat were positive in 16 of the 34 patients (12).

IgE antibodies against Foxtail millet were found in serum of patients with atopic dermatitis with or without bronchial asthma (9).

Other reactions

Crude extracts of Millet may contain aflatoxins (13).

Millet diets rich in C-glycosylflavones are goitrogenic (14).

Compiled by Dr Harris Steinman, harris@zingsolutions.com.

References

  1. Food and Agriculture Organization of the United Nations Sorghum and millets in human nutrition. ISBN 92-5-103381-1 www.fao.org/DOCREP/T0818e/T0818E01.htm 2008
  2. Parameswaran KP, Thayumanavan B. Homologies between prolamins of different minor millets. Plant Foods Hum Nutr 1995 Sep;48(2):119-26
  3. Takumi K, Udaka J, Kimoto M, Koga T, Tsuji H. Structural and immunochemical homologies between foxtail millet glutelin 60 kDa and starch granule-bound starch synthase proteins from rice, barley, corn and wheat grains. J Nutr Sci Vitaminol (Tokyo) 2000 Apr;46(2):109-12
  4. Parameswaran KP, Thayumanavan B. Isolation and characterization of a 20 kD prolamin from kodo millet (Paspalum scrobiculatum L.): homology with other millets and cereals.
    Plant Foods Hum Nutr 1997;50(4):359-73
  5. Tashiro M, Asao T, Nakano H, Takahashi K, Kanamori M. Purification and characterization of a subtilisin inhibitor from seeds of foxtail millet, Setaria italica.
    Agric Biol Chem 1991 Jan;55(1):265-7
  6. Pattabiraman TN. Trypsin/chymotrypsin inhibitors from millets.
    Adv Exp Med Biol 1986;199:439-48
  7. Tashiro M, Asao T, Hirata C, Takahashi K. Purification, characterization, and amino acid sequence of foxtail millet trypsin inhibitor III. Agric Biol Chem 1991 Feb;55(2):419-26
  8. Tashiro M, Asao T, Hirata C, Takahashi K, Kanamori M. The complete amino acid sequence of a major trypsin inhibitor from seeds of foxtail millet (Setaria italica).
    J Biochem 1990 Oct;108(4):669-72
  9. Urisu A, Yamada K, Masuda S, Komada H, Wada E, et al. 16-kilodalton rice protein is one of the major allergens in rice grain extract and responsible for cross-allergenicity between cereal grains in the Poaceae family. Int Arch Allergy Appl Immunol 1991;96(3):244-52
  10. Yamada K, Urisu A, Komada H, Inagaki Y, Yamada M, Nakamura R, Torii S. The involvement of rice protein 16KD in cross-allergenicity between antigens in rice, wheat, corn, Japanese millet, Italian millet. [Japanese] Arerugi 1991;40(12):1485-92
  11. Izumi H, Adachi T, Fujii N, Matsuda T, Nakamura R, Tanaka K, Urisu A, Kurosawa Y. Nucleotide sequence of a cDNA clone encoding a major allergenic protein in rice seeds. Homology of the deduced amino acid sequence with members of alpha-amylase/trypsin inhibitor family.
    FEBS Lett 1992;302(3):213-6
  12. Varjonen E, Vainio E, Kalimo K, Juntunen-Backman K, Savolainen J. Skin-prick test and RAST responses to cereals in children with atopic dermatitis. Characterization of IgE-binding components in wheat and oats by an immunoblotting method.
    Clin Exp Allergy 1995;25(11):1100-7
  13. Gupta SK. Venkitasubramanian, TA. Production of aflatoxin on soybeans.
    Applied Micro 1975;29:834-6
  14. Gaitan E, Cooksey RC, Legan J, Lindsay RH. Antithyroid effects in vivo and in vitro of vitexin: a C-glucosylflavone in millet. J Clin Endocrinol Metab 1995 Apr;80(4):1144-7

As in all diagnostic testing, the diagnosis is made by the physican based on both test results and the patient history.