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Onions and other alliums

Onions and other alliums

Onions and other alliums

Description
Biennial glabrous herb, usually grown as an annual from seed or bulbs, up to 100 cm tall; real stem very short, formed at the base of the plant in the form of a disk, with adventitious roots at base; bulbs formed by the thickening of leaf-bases a short distance above the true stem (2, 8).

Origin and geographic distribution
Allium cepa (botanical name for onions and most relatives such as shallots or scallions) probably originates from Central Asia (between Turkmenistan and Afghanistan) where some of its relatives still grow in the wild (8). Some of these close relatives (Allium vavilovii from southern Turkmenistan and northern Iran and Allium asarense from Iran) give 100% fertile hybrids (8). From Central Asia the supposed onion ancestor probably migrated first towards Mesopotamia, where onion is mentioned in Sumerian literature (2500 BC), then to Egypt (1600 BC), India and South-East Asia. From Egypt, Allium cepa was introduced into the Mediterranean area and from there to all the Roman Empire (8).

Uses
Onions (bulbs of Allium cepa) are a popular vegetable consumed worldwide. They are consumed raw or cooked, alone or in combination with other vegetables, as an ingredient of soups, dishes, sauces, sliced for seasoning salads, fried with meat. They are also used dried and in small amounts as a condiment or seasoning (for their pungency). The leaves, whole immature plants (Spring onions or scallions), or leafy sprouts from germinating bulbs (Chives) are used in the same way. In some parts of Africa, the immature flower heads are also a popular food item (8). It is said that sliced raw onions have antibiotic properties (8). Previous to modern medicine, onion was used externally to treat boils and wounds (8). It was also used to relieve coughs, bronchitis, asthma, gastro-intestinal disorders and headache (8).

Interest in the bioactive properties of Allium species is not new, with therapeutic formulas based on onion and garlic for treatment of heart problems, headaches and tumours documented in the Codex Ebers, an Egyptian medical papyrus dated 1550 BC (9). Considerable more recent data shows significant health benefits associated with Allium consumption, including reduced risk of cancer, cardiovascular disease, reduced inflammatory response, anti-asthmatic, anti-diabetic, antioxidant, antibiotic and antifungal properties. Epidemiological and other studies have shown a correlation between onion consumption and incidence of a range of cancers including stomach and intestine, colon, ovary, breast, larynx, mouth and brain cancers (9-11).

 

References

  1. van der Vossen, H. A. M.; Kahangi, E., Daucus carota L. [Internet] Record from Protabase. In Grubben, G.J.H. & Denton, O.A. (Editors): 2004.
  2. Clapham, A. R.; Tutin, T. G.; Warburg, E. F., Flora of the British Isles. 3rd ed.; University Press, Cambridge: London, 1958; p 1592.
  3. Surles, R. L.; Weng, N.; Simon, P. W.; Sherry, A. T. T., Carotenoid profiles and consumer sensory evaluation of specialty carrots (Daucus carota, L.) of various colors. Journal of Agricultural and Food Chemistry 2004, 52, (11), 3417-3421.
  4. Simon, P. W., Plant pigments for color and nutrition. Hortscience 1997, 32, (1), 12-13.
  5. Metzger, B. T.; Barnes, D. M.; Reed, J. D., Purple carrot (Daucus carota L.) polyacetylenes decrease lipopolysaccharide-induced expression of inflammatory proteins in macrophage and endothelial cells. Journal of Agricultural and Food Chemistry 2008, 56, (10), 3554-3560.
  6. Schnabele, K.; Briviba, K.; Bub, A.; Roserl, S.; Pool-Zobel, B. L.; Rechkemmer, G., Effects of carrot and tomato juice consumption on faecal markers relevant to colon carcinogenesis in humans. British Journal of Nutrition 2008, 99, (3), 606-613.
  7. Oyen, L. P. A., Pastinaca sativa L. [Internet] Record from Protabase. In Grubben, G.J.H. & Denton, O.A. (Editors): 2004.
  8. Messiaen, C.-M.; Rouamba, A., Allium cepa L. [Internet] Record from Protabase. . In Grubben, G.J.H. & Denton, O.A. (Editors): 2004.
  9. Lanzotti, V., The analysis of onion and garlic. Journal of Chromatography A 2006, 1112, (1-2), 3-22.
  10. Desjardins, Y., Onion as a Nutraceutical and Functional Food. Chronica Horticulturae 2008, 48, (2), 8 - 14.
  11. Galeone, C.; Pelucchi, C.; Levi, F.; Negri, E.; Franceschi, S.; Talamini, R.; Giacosa, A.; La Vecchia, C., Onion and garlic use and human cancer. Am J Clin Nutr 2006, 84, (5), 1027-1032.
  12. Tjeertes, P., Brassica oleracea L. (cauliflower and broccoli) [Internet] Record from Protabase. . In Grubben, G.J.H. & Denton, O.A. (Editors): 2004.