Gyromitra Esculenta - Toxicity

Toxicity

Toxic reactions have been known for at least a hundred years. Experts speculated the reaction was more of an allergic one specific to the consumer, or a misidentification, rather than innate toxicity of the fungus, due to the wide range in effects seen. Some would suffer severely or perish while others exhibited no symptoms after eating similar amounts of mushrooms from the same dish. Yet others would be poisoned after eating Gyromitra esculenta for many years without ill-effects. However, the fungus is now widely recognized as potentially deadly.

Gyromitra esculenta contains levels of the poison gyromitrin that vary locally among populations; although these mushrooms are only rarely involved in poisonings in either North America or Western Europe, intoxications are seen frequently in eastern Europe and Scandinavia. A 1971 Polish study reported at the time that the species accounted for up to 23% of mushroom fatalities each year. Death rates have dropped since the mid-twentieth century; in Sweden poisoning is common, though life-threatening poisonings have not been detected and there was no fatality reported over the 50 years from 1952 to 2002. Gyromitra poisonings are rare in Spain, due to the widespread practice of drying the mushrooms before preparation and consumption, but has a mortality rate of about 25%.

A lethal dose of gyromitrin has been estimated to be 10–30 mg/kg for children and 20–50 mg/kg in adults. These doses correspond to around 0.2–0.6 kilogram (0.4–1.3 lb) and 0.4–1 kilogram (0.9–2.2 lb) of fresh mushroom respectively. However, individual responses may vary and people who have ingested similar amounts may develop anything from minimal to severe toxicity. Evidence suggests that children are more severely affected; it is unclear whether this is due to a larger weight consumed per body mass ratio or to differences in enzyme and metabolic activity. Although the amount of gyromitrin present can be significantly reduced through parboiling, there is evidence that repeated consumption can increase risk of toxicity.