Atlantic Canada Based Homebrew & Beer Appreciation Club
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Toxicity
There has been concern over the safety of sweet flag, which is currently banned in food products in North America. This prohibition was based on cancerous tumours developed in laboratory animals treated with sweet flag high in content of carcinogenic b-asarone. Carcinogenic b-asarone is present in large amounts in Asian plants, and in limited amounts in European plants. The apparent absence of this and other toxic phenylpropane derivatives in the plants of North America may represent a means of using sweet flag relatively safely. However, it is important to realize that even if North American sweet flag lacks the carcinogenic substances found in the plants of the Old World, under certain conditions it is still reputed to be poisonous, producing disturbed digestion, gastroenteritis, constipation, and bloody diarrhea. The volatile oil causes dermatitis on contact with the skin in some individuals. It should be emphasized in view of the toxic potential of the plant, that any kind of personal use without the supervision of an informed physician is hazardous.
Anyone contemplating using sweet flag as food should also be cautioned that aquatic plants growing in contaminated water may harbour harmful chemicals and organisms acquired from the water. The possibility also exists for those collecting rhizomes in aquatic habitats that the seriously poisonous water hemlock (Cicuta maculata L.) could be mistakenly collected.
This herb was listed in 1995 Health Canada document, Herbs used as non-medicinal ingredients in nonprescription drugs for human use, as unacceptable as a non-prescription drug product for oral use.