Kalmia latifolia L. - syn.Kalmia lucida Koch; Kalmia nitida Forbes. - Ericaceae
mountain laurel, American laurel, broadleaved laurel, spoonwood, Amerikanischer Lorbeer, Kalmie, Breitblättriger Lorbeer
Evergreen shrub, native to eastern North America (USA).
„Mountain laurel is poisonous to several different animals due to grayanotoxin and arbutin, including horses, goats, cattle, deer, monkeys and humans. The green parts of the plant, flowers, twigs, and pollen are all toxic, including food products made from them, such as toxic honey that may produce neurotoxic and gastrointestinal symptoms in humans eating more than a modest amount. Fortunately the honey is sufficiently bitter to discourage most people from eating it…“ http://en.wikipedia.org/wiki/Kalmia_latifolia
Grayanotoxin I from K.angustifolia var.caroliniana (sheep laurel) and K.latifolia was found to be identical to acetylandromedol (andromedotoxin) from Andromeda and Rhododendron species.
[Studies on the occurrence and structure of acetylandromedol (andromedotoxin)., Tallent, W.H., Riethof, M.L., Horning, E.C., Journal of the American Chemical Society, Vol.79(16), 1957, 4548-4554]
[Über Acetylandromedol (Andromedotoxin) in verschiedenen Ericaceen, insbesondere in Rhododendron, und seine annähernde Bestimmung. Schindler, H., Planta Medica, Vol.10(02), 1962, 232-237]
Samples of Honey from the Turkish Black Sea region contained high levels of grayanotoxin, which lead to acute poisoning with dizziness, blood pressure drop, slow heartbeat, paralysis, nausea, vomiting and diarrhea.
„Grayanotoxins are plant poisons, which are mainly found in the Rhododendron species. In humans, the consumption of the said honey may lead to poisoning phenomena, which must be dealt with by emergency medical treatment.“
[Bundesinstitut für Risikobewertung, Stellungnahme Nr. 043/2010 des BfR vom 3. September 2010] http://www.bfr.bund.de/cm/343/vergiftungsfaelle_durch_grayanotoxine_in_rhododendron_honigen_aus_der_tuerkischen_schwarzmeerregion.pdf
„Many plants of the Ericaceae family, Rhododendron, Pieris, Agarista and Kalmia, contain diterpene grayanotoxins. Consumption of grayanotoxin containing leaves, flowers or secondary products as honey may result in intoxication specifically characterized by dizziness, hypotension and atrial-ventricular block. Symptoms are caused by an inability to inactivate neural sodium ion channels resulting in continuous increased vagal tone. Grayanotoxin containing products are currently sold online, which may pose an increasing risk. In humans, intoxication is rarely lethal, in contrast to cattle and pet poisoning cases. Scientific evidence for the medicinal properties of grayanotoxin containing preparations, such as honey or herbal preparation in use in folk medicine, is scarce, and such use may even be harmful.“
[Grayanotoxin poisoning:‘mad honey disease’and beyond.,Jansen, S.A., Kleerekooper, I., Hofman, Z.L., Kappen, I.F., Stary-Weinzinger, A., van der Heyden, M.A., Cardiovascular toxicology, Vol.12(3), 2012, 208-215]
Tolerable daily intake (TDI) of grayanotoxin is indicated with 0.05µg/kg body weight and may be exceeded in consumers taking homoeopathic medicines made from K.latifolia.
[36/17 Informationen der Institutionen und Behörden: BfArM: Schriftliche Anhörung gemäß Stufenplanverfahren zu Andromedotoxin/Grayanotoxin-haltigen homöopathischen Arzneimitteln, 2017] https://www.abda.de/amk-nachricht/artikel/3617-informationen-der-institutionen-und-behoerden-bfarm-schriftliche-anhoerung-gemaess-stufenplanver/
© Rolf Marschner (2014), www.botanische-spaziergaenge.at