Wild Flowers and Mad Honey

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To the Editor: One unusual form of food poisoning, commonly seen in the eastern Black Sea region, is caused by toxic honey, which is familiar to local people and which is known as “mad honey.” It has been known to be poisonous since 401 bc.1.Avcı M. Rhododendrons and their natural occurrences in Turkey.CoğrafyaDergisi. 2004; 12: 1319Google Scholar Grayanotoxins, which are extracted by bees from the flowers of rhododendron species, are the main compounds responsible for this poisoning. Ericaceae is one of the largest dicotelydon genera. The name “rhododendron” derives from the Greek rhodos, meaning “rose,” and dendron, meaning “tree.” There are some 700 different species in the area comprising China, Tibet, Myanmar, Assam, and Nepal; nearly 300 species in New Guinea; many in Japan; others in tropical Asia from Indochina to Indonesia and the Philippines; and a small number occur in Europe and North America. Purple-flowered (Rhododendron ponticum) (Figure 1) and yellow-flowered (Rhododendron luteum) (Figure 2) rhododendrons have become pernicious woody weeds in northern Turkey.2.Terzioğlu S. Merev N. Anşin R. A study on Turkish Rhododendron L. (Ericaceae).Turk J Agric For. 2001; 25: 311-317Google Scholar The former are also known as “black poison” and the latter as “yellow poison.” As a result of the grayanotoxins they contain, the flowers of these 2 rhododendron species, which are widely found in the mountains that extend along the Black Sea coast of northern Turkey, may lead to poisoning of honey made by local producers and produced by wild bees. The grayanotoxins bind to the sodium channels in cell membranes. These compounds prevent inactivation; thus, excitable cells (nerve and muscle) are maintained in a state of depolarization, during which entry of calcium into the cells may be facilitated.3.Onat F.Y. Yegen B.C. Lawrence R. et al.Mad honey poisoning in man and rat.Rev Environ Health. 1991; 9: 3-9Crossref PubMed Scopus (80) Google ScholarFigure 2Rhododendron luteum, also known as the “mountain rose” or “yellow poison.”View Large Image Figure ViewerDownload Hi-res image Download (PPT) Toxic Rhododendron species, particularly R ponticum, are commonly used in folk medicines of the Black Sea region. R ponticum is widely used both internally and externally as an analgesic for treatment of rheumatic or dental pain, common viral upper respiratory infections, and edema.4.Baytop T. Therapy With Medicinal Plants in Turkey, Past and Present.2nd ed. Nobel Tıp Basımevi, Istanbul, Turkey1999Google Scholar “Mad honey” is used as an alternative medicine for the treatment of gastric pains, bowel disorders, and hypertension and is also believed to be a sexual stimulant. Beekeeping is a common activity among the inhabitants of the eastern Black Sea region. Native Caucasian bees (Apis mellifera caucasica), which fly in an area of only some 5 km,2.Terzioğlu S. Merev N. Anşin R. A study on Turkish Rhododendron L. (Ericaceae).Turk J Agric For. 2001; 25: 311-317Google Scholar are used in the traditional method of honey production. Since rhododendrons are long-lived plants, beekeepers know which honey is “mad.” Honey produced in springtime is more toxic and sometimes contains higher concentrations of grayanotoxins than that produced in other seasons.5.Dilber E. Kalyoncu M. Yarifi N. et al.A case of mad honey poisoning presenting with convulsion: intoxication instead of alternative therapy.Turk J Med Sci. 2002; 32: 361-362Google Scholar Well-known toxic effects of honey poisoning are bradycardia, cardiac arrhythmia, hypotension, nausea, vomiting, sweating, salivation, dizziness, weakness, loss of consciousness, fainting, blurred vision, chills, cyanosis, and convulsions.5.Dilber E. Kalyoncu M. Yarifi N. et al.A case of mad honey poisoning presenting with convulsion: intoxication instead of alternative therapy.Turk J Med Sci. 2002; 32: 361-362Google Scholar,6.Sutlupinar N. Mat A. Satganoglu Y. Poisoning by toxic honey in Turkey.Arch Toxicol. 1993; 67: 148-150Crossref PubMed Scopus (87) Google Scholar Poisoning is frequently seen in this region,7.Yavuz H. Özel A. Akkus I. et al.Honey poisoning in Turkey.Lancet. 1991; 337: 789-790Abstract PubMed Scopus (41) Google Scholar and patients generally recover spontaneously without reporting to health institutions. The majority of those who do seek medical care recover with 0.5 to 1.0 mg of atropine and controlled fluid replacement. In rare, life-threatening cases, cardiac arrhythmias requiring cardiac pacing may occur. The potential hazards of these 2 wild flowers need to be appreciated along with their aesthetic qualities.