''Gyromitra esculenta'' is an
ascomycete
Ascomycota is a phylum of the kingdom Fungi that, together with the Basidiomycota, forms the subkingdom Dikarya. Its members are commonly known as the sac fungi or ascomycetes. It is the largest phylum of Fungi, with over 64,000 species. The def ...
fungus from the genus ''
Gyromitra'', widely distributed across Europe and North America. It normally fruits in sandy soils under
coniferous
Conifers () are a group of conifer cone, cone-bearing Spermatophyte, seed plants, a subset of gymnosperms. Scientifically, they make up the phylum, division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a sin ...
trees in spring and early summer. The
fruiting body, or mushroom, is an irregular brain-shaped
cap
A cap is a flat headgear, usually with a visor. Caps have crowns that fit very close to the head. They made their first appearance as early as 3200 BC. The origin of the word "cap" comes from the Old French word "chapeau" which means "head co ...
, dark brown in colour, that can reach high and wide, perched on a stout white
stipe up to high.
Although potentially fatal if eaten raw (causing restrictions on its sales in some areas), ''G. esculenta'' is still commonly
parboiled for consumption, being a popular delicacy in Europe and the upper
Great Lakes region
The Great Lakes region of Northern America is a binational Canadian– American region centered on the Great Lakes that includes the U.S. states of Illinois, Indiana, Michigan, Minnesota, New York, Ohio, Pennsylvania, and Wisconsin and the Ca ...
of
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
; evidence suggests that thorough cooking does not eliminate all traces of mycotoxins. When consumed, the principal active mycotoxin,
gyromitrin, is
hydrolyzed
Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile.
Biological hydrolysi ...
into the toxic compound
monomethylhydrazine
Monomethylhydrazine (MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide () ...
, which
affects the liver,
central nervous system
The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...
, and sometimes the
kidneys
In humans, the kidneys are two reddish-brown bean-shaped blood-filtering organs that are a multilobar, multipapillary form of mammalian kidneys, usually without signs of external lobulation. They are located on the left and right in the retro ...
. Symptoms of poisoning involve vomiting and diarrhea several hours after consumption, followed by dizziness, lethargy and headache. Severe cases may lead to
delirium
Delirium (formerly acute confusional state, an ambiguous term that is now discouraged) is a specific state of acute confusion attributable to the direct physiological consequence of a medical condition, effects of a psychoactive substance, or ...
, coma, and death after five to seven days.
Taxonomy
The fungus was first described in 1800, by
mycologist
Mycology is the branch of biology concerned with the study of fungi, including their taxonomy, genetics, biochemical properties, and use by humans. Fungi can be a source of tinder, food, traditional medicine, as well as entheogens, poison, and ...
Christian Hendrik Persoon
Christiaan Hendrik Persoon (31 December 1761 – 16 November 1836) was a Cape Colony mycologist who is recognized as one of the founders of mycology, mycological Taxonomy (biology), taxonomy.
Early life
Persoon was born in Cape Colony at ...
, as ''Helvella esculenta'', and gained its current accepted
binomial name
In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...
when the Swedish mycologist
Elias Magnus Fries
Elias Magnus Fries (15 August 1794 – 8 February 1878) was a Swedish mycologist and botanist. He is sometimes called the Mycology, "Linnaeus of Mycology". In his works he described and assigned botanical names to hundreds of fungus and li ...
placed it in the genus ''Gyromitra'' in 1849. The genus name is derived from the
Greek
Greek may refer to:
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group
*Greek language, a branch of the Indo-European language family
**Proto-Greek language, the assumed last common ancestor of all kno ...
terms ''gyros''/γυρος "round" and ''mitra''/μιτρα "headband".
Its specific epithet is derived from the
Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
''esculentus'', "edible".
It is known by a variety of common descriptive names such as "brain mushroom",
"turban fungus",
[ ''elephant ears'', or "beefsteak mushroom/morel", although ''beefsteak mushroom'' can also refer to the much choicer edible basidiomycete '']Fistulina hepatica
''Fistulina hepatica'', commonly known as the beefsteak fungus, beefsteak polypore, poor man's steak, ox tongue, or tongue mushroom, is a bracket fungus classified in the Agaricales. As its common names suggest, it visually resembles a sla ...
''. Dating from the 19th century, the German term is a result of the older , itself from the 18th century Low German
Low German is a West Germanic languages, West Germanic language variety, language spoken mainly in Northern Germany and the northeastern Netherlands. The dialect of Plautdietsch is also spoken in the Russian Mennonite diaspora worldwide. "Low" ...
, aligning with the similar-sounding (and similar-looking) .
''Gyromitra esculenta'' is a member of a group of fungi known as " false morels", so named for their resemblance to the highly regarded true morels of the genus '' Morchella''. The grouping includes other species of the genus ''Gyromitra'', such as '' G. infula'' (elfin saddle), '' G. caroliniana'' and '' G. gigas'' (snow morel). While some of these species contain little to no gyromitrin, many guidebooks recommend treating them all as poisonous, since their similar appearance and significant intraspecific variation can make reliable identification difficult. The toxic qualities of ''G. esculenta'' may be reduced by cooking, but possibly not enough to prevent poisoning from repeated consumption.
The more distantly related ascomycete mushrooms of the genus '' Verpa'', such as '' V. bohemica'' and '' V. conica'', are also known as false morels, early morels or thimble morels; like the '' Gyromitra'', they are eaten by some and considered poisonous by others.
The genus ''Gyromitra'' had been classically considered part of the family Helvellaceae, along with the similar-looking elfin saddles of the genus '' Helvella''. Analysis of the ribosomal DNA
The ribosomal DNA (rDNA) consists of a group of ribosomal RNA encoding genes and related regulatory elements, and is widespread in similar configuration in all domains of life. The ribosomal DNA encodes the non-coding ribosomal RNA, integral struc ...
of many of the Pezizales
The Pezizales are an order of the subphylum Pezizomycotina within the phylum Ascomycota. The order contains 16 families, 199 genera, and 1683 species. It contains a number of species of economic importance, such as morels, the black and whit ...
showed ''G. esculenta'' and the other false morels to be only distantly related to the other members of the Helvellaceae and instead most closely related to the genus '' Discina'', forming a clade
In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...
which also contains '' Pseudorhizina'' and '' Hydnotrya''. Thus the four genera are now included in the family Discinaceae.
Description
Resembling a brain, the irregularly shaped cap
A cap is a flat headgear, usually with a visor. Caps have crowns that fit very close to the head. They made their first appearance as early as 3200 BC. The origin of the word "cap" comes from the Old French word "chapeau" which means "head co ...
may be up to high and wide. Initially smooth, it becomes progressively more wrinkled as it grows and ages. The cap colour may be various shades of reddish-, chestnut-, purplish-, bay-, dark or sometimes golden-brown; it darkens to black in age. Specimens from California may have more reddish-brown caps. Attached to the cap at several points, the stipe is high and wide. ''G. esculenta'' has been reported to have a solid stipe whereas those of true morels ('' Morchella'' spp.) are hollow, although a modern source says it is hollow as well. The smell can be pleasant and has been described as fruity, and the fungus is mild-tasting. The spore print
300px, Making a spore print of the mushroom ''Volvariella volvacea'' shown in composite: (photo lower half) mushroom cap laid on white and dark paper; (photo upper half) cap removed after 24 hours showing warm orange ("tussock") color spore print. ...
is whitish, with transparent spores that are elliptical and 17–22 μm in length.
Similar species
''G. esculenta'' resembles the various species of true morel, although the latter are more symmetric and look more like pitted gray, tan, or brown sponge
Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and a ...
s. Its cap is generally darker and larger.
''G. gigas'', ''G. infula'' and '' G. ambigua'' in particular are similar, the latter two being toxic to humans.
Distribution and habitat
''G. esculenta'' grows on sandy soil in temperate coniferous forest
Temperate coniferous forest is a terrestrial biome defined by the World Wide Fund for Nature. Temperate coniferous forests are found predominantly in areas with warm summers and cool winters, and vary in their kinds of plant life. In some, needle ...
and occasionally in deciduous woodlands. Among conifers it is mostly found under pines (''Pinus
A pine is any conifer tree or shrub in the genus ''Pinus'' () of the family Pinaceae. ''Pinus'' is the sole genus in the subfamily Pinoideae.
''World Flora Online'' accepts 134 species-rank taxa (119 species and 15 nothospecies) of pines as c ...
'' spp.), but also sometimes under aspens (''Populus
''Populus'' is a genus of 25–30 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar (), aspen, and cottonwood.
The we ...
'' spp.). The hunting period is from April to July, earlier than for other species, and the fungus may even sprout up with the melting snow. It can be abundant in some years and rare in others. The mushroom is more commonly found in places where ground has been disturbed, such as openings, rivulets, washes, timber clearings, plowed openings, forest fire clearings, and roadsides. Enthusiasts in Finland have been reported burying newspaper inoculated with the fungus in the ground in autumn and returning the following spring to collect mushrooms.
Although more abundant in montane
Montane ecosystems are found on the slopes of mountains. The alpine climate in these regions strongly affects the ecosystem because temperatures lapse rate, fall as elevation increases, causing the ecosystem to stratify. This stratification is ...
and northern coniferous woodlands such as the Sierra Nevada
The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...
and the Cascade Range
The Cascade Range or Cascades is a major mountain range of western North America, extending from southern British Columbia through Washington (state), Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as m ...
in northwestern North America, ''Gyromitra esculenta'' is found widely across the continent, as far south as Mexico
Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...
. It is also common in Central Europe
Central Europe is a geographical region of Europe between Eastern Europe, Eastern, Southern Europe, Southern, Western Europe, Western and Northern Europe, Northern Europe. Central Europe is known for its cultural diversity; however, countries in ...
, less abundant in the east, and more in montane areas than lowlands. It has been recorded from Northern Ireland
Northern Ireland ( ; ) is a Countries of the United Kingdom, part of the United Kingdom in the north-east of the island of Ireland. It has been #Descriptions, variously described as a country, province or region. Northern Ireland shares Repub ...
, from Uşak Province
Uşak () is a Provinces of Turkey, province in western Turkey. Its adjacent provinces are Manisa Province, Manisa to the west, Denizli Province, Denizli to the south, Afyon Province, Afyon to the east, and Kütahya Province, Kütahya to the north. ...
in Western Turkey, and from the vicinity of Kaş
Kaş () is a small fishing, diving, yachting and tourist town, and a municipality and Districts of Turkey, district of Antalya Province, Turkey. Its area is 1,750 km2, and its population is 62,866 (2022). It is 168 km west of the city ...
in the Antalya Province
Antalya Province () is a Provinces of Turkey, province and Metropolitan municipalities in Turkey, metropolitan municipality of Turkey. It is located on the Mediterranean Region, Turkey, Mediterranean coast of south-west Turkey, between the Taur ...
of Turkey's southern coast.
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 not poisoned after eating ''G. esculenta'' for many years. 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
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
or western Europe
Western Europe is the western region of Europe. The region's extent varies depending on context.
The concept of "the West" appeared in Europe in juxtaposition to "the East" and originally applied to the Western half of the ancient Mediterranean ...
, intoxications are seen frequently in eastern Europe
Eastern Europe is a subregion of the Europe, European continent. As a largely ambiguous term, it has a wide range of geopolitical, geographical, ethnic, cultural and socio-economic connotations. Its eastern boundary is marked by the Ural Mountain ...
and Scandinavia
Scandinavia is a subregion#Europe, subregion of northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. ''Scandinavia'' most commonly refers to Denmark, Norway, and Sweden. It can sometimes also ...
. 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
Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
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, .
A lethal dose
In toxicology, the lethal dose (LD) is an indication of the lethal toxicity of a given substance or type of radiation. Because resistance varies from one individual to another, the "lethal dose" represents a dose (usually recorded as dose per kilog ...
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 and of fresh mushroom respectively. 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.
Geographical variation
Populations of ''G. esculenta'' appear to vary geographically in their toxicity. A French study has shown that mushrooms collected at higher altitudes have lower concentrations of toxin than those from lower elevations, and there is some evidence that fungi west of the Rocky Mountains
The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in great-circle distance, straight-line distance from the northernmost part of Western Can ...
in North America contain less toxin than those to the east. However, poisonings in the USA have been reported, although less frequently than in Europe.
Biochemistry
The identity of the toxic constituents eluded researchers until 1968, when acetaldehyde ''N''-methyl-''N''-formylhydrazone, better known as gyromitrin, was isolated. Gyromitrin is a volatile, water-soluble
In chemistry, solubility is the ability of a substance, the solute, to form a solution with another substance, the solvent. Insolubility is the opposite property, the inability of the solute to form such a solution.
The extent of the solub ...
hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydraz ...
compound hydrolyzed in the body into ''N''-methyl-''N''-formylhydrazine (MFH) then monomethylhydrazine
Monomethylhydrazine (MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide () ...
(MMH). Other ''N''-methyl-''N''-formylhydrazone derivatives have been isolated in subsequent research, although they are present in smaller amounts. These other compounds would also produce monomethylhydrazine when hydrolyzed, although it remains unclear how much each contributes to the false morel's toxicity.
The toxins react with pyridoxal-5-phosphate—the activated form of pyridoxine
Pyridoxine (PN) is a form of vitamin B6 found commonly in food and used as a dietary supplement. As a supplement it is used to treat and prevent pyridoxine deficiency, sideroblastic anaemia, pyridoxine-dependent epilepsy, certain metaboli ...
(vitamin B6)—and form a hydrazone
Hydrazones are a class of organic compounds with the structure . They are related to ketones and aldehydes by the replacement of the oxygen =O with the = functional group. They are formed usually by the action of hydrazine on ketones or aldehydes. ...
. This reduces production of the neurotransmitter GABA
GABA (gamma-aminobutyric acid, γ-aminobutyric acid) is the chief inhibitory neurotransmitter in the developmentally mature mammalian central nervous system. Its principal role is reducing neuronal excitability throughout the nervous system.
GA ...
via decreased activity of glutamic acid decarboxylase
Glutamate decarboxylase or glutamic acid decarboxylase (GAD) is an enzyme that catalyzes the decarboxylation of glutamate to gamma-aminobutyric acid (GABA) and carbon dioxide (). GAD uses pyridoxal-phosphate (PLP) as a cofactor. The reaction pr ...
, producing the neurological symptoms. MMH also causes oxidative stress
Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal ...
leading to methemoglobinemia
Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). Complications ma ...
. Inhibition of diamine oxidase (histaminase) elevates histamine
Histamine is an organic nitrogenous compound involved in local immune responses communication, as well as regulating physiological functions in the gut and acting as a neurotransmitter for the brain, spinal cord, and uterus. Discovered in 19 ...
levels resulting in headaches, nausea, vomiting, and abdominal pain.
MFH, as a mushroom component and an intermediary product of gyromitrin hydrolysis, has toxicities of its own. MFH undergoes cytochrome P450
Cytochromes P450 (P450s or CYPs) are a Protein superfamily, superfamily of enzymes containing heme as a cofactor (biochemistry), cofactor that mostly, but not exclusively, function as monooxygenases. However, they are not omnipresent; for examp ...
-regulated oxidative metabolism which, via reactive nitrosamide intermediates, leads to formation of methyl radicals which lead to liver necrosis.
Symptoms
The symptoms of poisoning are typically gastrointestinal
The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. ...
and neurological
Neurology (from , "string, nerve" and the suffix -logia, "study of") is the branch of medicine dealing with the diagnosis and treatment of all categories of conditions and disease involving the nervous system, which comprises the brain, the s ...
. Symptoms occur within 6–12 hours of consumption, although cases of more severe poisoning may present sooner—as little as 2 hours after ingestion. Initial symptoms are gastrointestinal, with sudden onset of nausea
Nausea is a diffuse sensation of unease and discomfort, sometimes perceived as an urge to vomit. It can be a debilitating symptom if prolonged and has been described as placing discomfort on the chest, abdomen, or back of the throat.
Over 30 d ...
, vomiting, and watery diarrhea
Diarrhea (American English), also spelled diarrhoea or diarrhœa (British English), is the condition of having at least three loose, liquid, or watery bowel movements in a day. It often lasts for a few days and can result in dehydration d ...
which may be bloodstained. Dehydration
In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...
may develop if the vomiting or diarrhea is severe. Dizziness, lethargy, vertigo
Vertigo is a condition in which a person has the sensation that they are moving, or that objects around them are moving, when they are not. Often it feels like a spinning or swaying movement. It may be associated with nausea, vomiting, perspira ...
, tremor, ataxia
Ataxia (from Greek α- negative prefix+ -τάξις rder= "lack of order") is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in e ...
, nystagmus
Nystagmus is a condition of involuntary (or voluntary, in some cases) Eye movement (sensory), eye movement. People can be born with it but more commonly acquire it in infancy or later in life. In many cases it may result in visual impairment, re ...
, and headaches develop soon after; fever
Fever or pyrexia in humans is a symptom of an anti-infection defense mechanism that appears with Human body temperature, body temperature exceeding the normal range caused by an increase in the body's temperature Human body temperature#Fever, s ...
often occurs, a distinctive feature which does not develop after poisoning by other types of mushrooms. In most cases of poisoning, symptoms do not progress from these initial symptoms, and patients recover after 2–6 days of illness.
In some cases there may be an asymptomatic
Asymptomatic (or clinically silent) is an adjective categorising the medical conditions (i.e., injuries or diseases) that patients carry but without experiencing their symptoms, despite an explicit diagnosis (e.g., a positive medical test).
P ...
phase following the initial symptoms which is then followed by more significant toxicity including kidney damage, liver damage
Liver disease, or hepatic disease, is any of many diseases of the liver. If long-lasting it is termed chronic liver disease. Although the diseases differ in detail, liver diseases often have features in common.
Liver diseases
File:Ground glas ...
, and neurological dysfunction including seizures and coma. These signs usually develop within 1–3 days in serious cases. The patient develops jaundice
Jaundice, also known as icterus, is a yellowish or, less frequently, greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving ...
and the liver and spleen become enlarged; in some cases blood sugar
The blood sugar level, blood sugar concentration, blood glucose level, or glycemia is the measure of glucose concentrated in the blood. The body tightly regulates blood glucose levels as a part of metabolic homeostasis.
For a 70 kg (1 ...
levels will rise (hyperglycemia
Hyperglycemia is a condition where unusually high amount of glucose is present in blood. It is defined as blood glucose level exceeding 6.9 mmol/L (125 mg/dL) after fasting for 8 hours or 10 mmol/L (180 mg/dL) 2 hours after eating.
Blood gluc ...
) and then fall (hypoglycemia
Hypoglycemia (American English), also spelled hypoglycaemia or hypoglycæmia (British English), sometimes called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's tria ...
) and liver toxicity is seen. Additionally intravascular hemolysis
Hemolysis or haemolysis (), also known by #Nomenclature, several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may ...
causes destruction of red blood cells resulting in increase in free hemoglobin and hemoglobinuria which can lead to renal toxicity or kidney failure
Kidney failure, also known as renal failure or end-stage renal disease (ESRD), is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney fa ...
. Methemoglobinemia
Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). Complications ma ...
may also occur in some cases. This is where higher than normal levels of methemoglobin
Methemoglobin (British: methaemoglobin, shortened MetHb) (pronounced "met-hemoglobin") is a hemoglobin ''in the form of metalloprotein'', in which the iron in the heme group is in the Fe3+ (ferric) state, not the Fe2+ (ferrous) of normal hemoglobin ...
, which is a form of hemoglobin that can not carry oxygen, are found in the blood. It causes the patient to become short of breath and cyanotic
Cyanosis is the change of tissue color to a bluish-purple hue, as a result of decrease in the amount of oxygen bound to the hemoglobin in the red blood cells of the capillary bed. Cyanosis is apparent usually in the body tissues covered with ...
. Cases of severe poisoning may progress to a terminal neurological phase, with delirium
Delirium (formerly acute confusional state, an ambiguous term that is now discouraged) is a specific state of acute confusion attributable to the direct physiological consequence of a medical condition, effects of a psychoactive substance, or ...
, muscle fasciculation
A fasciculation, or muscle twitch, is a spontaneous, involuntary muscle contraction and relaxation, involving fine muscle fibers. They are common, with as many as 70% of people experiencing them. They can be benign, or associated with more seriou ...
s and seizures, and mydriasis
Mydriasis is the Pupillary dilation, dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response. Non-physiological causes of mydriasis include disease, Physical trauma, trauma, or the use of c ...
progressing to coma
A coma is a deep state of prolonged unconsciousness in which a person cannot be awakened, fails to Nociception, respond normally to Pain, painful stimuli, light, or sound, lacks a normal Circadian rhythm, sleep-wake cycle and does not initiate ...
, circulatory collapse, and respiratory arrest
Respiratory arrest is a serious medical condition caused by apnea or respiratory dysfunction severe enough that it will not sustain the body (such as agonal breathing). Prolonged apnea refers to a patient who has stopped breathing for a long period ...
. Death may occur from five to seven days after consumption.
Treatment
Treatment is mainly supportive; gastric decontamination with activated charcoal
"Activated" is a song by English singer Cher Lloyd. It was released on 22 July 2016 through Vixen Records. The song was made available to stream exclusively on ''Rolling Stone'' a day before to release (on 21 July 2016).
Background
In an inter ...
may be beneficial if medical attention is sought within a few hours of consumption. However, symptoms often take longer than this to develop, and patients do not usually present for treatment until many hours after ingestion, thus limiting its effectiveness. Patients with severe vomiting or diarrhea can be rehydrated with intravenous fluids
Intravenous therapy (abbreviated as IV therapy) is a medical technique that administers fluids, medications and nutrients directly into a person's vein. The intravenous route of administration is commonly used for rehydration or to provide nutr ...
. Monitoring of biochemical parameters such as methemoglobin levels, electrolytes, liver and kidney function, urinalysis
Urinalysis, a portmanteau of the words ''urine'' and ''analysis'', is a Test panel, panel of medical tests that includes physical (macroscopic) examination of the urine, chemical evaluation using urine test strips, and #Microscopic examination, m ...
, and complete blood count
A complete blood count (CBC), also known as a full blood count (FBC) or full haemogram (FHG), is a set of medical laboratory tests that provide cytometry, information about the cells in a person's blood. The CBC indicates the counts of white blo ...
is undertaken and any abnormalities are corrected. Dialysis can be used if kidney function is impaired or the kidneys are failing. Hemolysis may require a blood transfusion
Blood transfusion is the process of transferring blood products into a person's Circulatory system, circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used ...
to replace the lost red blood cells, while methemoglobinemia
Methemoglobinemia, or methaemoglobinaemia, is a condition of elevated methemoglobin in the blood. Symptoms may include headache, dizziness, shortness of breath, nausea, poor muscle coordination, and blue-colored skin (cyanosis). Complications ma ...
is treated with intravenous methylene blue
Methylthioninium chloride, commonly called methylene blue, is a salt used as a dye and as a medication. As a medication, it is mainly used to treat methemoglobinemia. It has previously been used for treating cyanide poisoning and urinary trac ...
.
Pyridoxine, also known as vitamin B6
Vitamin B6 is one of the B vitamins, and is an essential nutrient for humans. The term essential nutrient refers to a group of six chemically similar compounds, i.e., "vitamers", which can be interconverted in biological systems. Its active f ...
, can be used to counteract the inhibition
Inhibitor or inhibition may refer to:
Biology
* Enzyme inhibitor, a substance that binds to an enzyme and decreases the enzyme's activity
* Reuptake inhibitor, a substance that increases neurotransmission by blocking the reuptake of a neurotransm ...
by MMH on the pyridoxine-dependent step in the synthesis of the neurotransmitter GABA
GABA (gamma-aminobutyric acid, γ-aminobutyric acid) is the chief inhibitory neurotransmitter in the developmentally mature mammalian central nervous system. Its principal role is reducing neuronal excitability throughout the nervous system.
GA ...
. Thus GABA synthesis can continue and symptoms are relieved. Pyridoxine, which is only useful for the neurological symptoms and does not decrease hepatic toxicity, is given at a dose of 25 mg/kg; this can be repeated up to a maximum total of 15 to 30 g daily if symptoms do not improve. Benzodiazepine
Benzodiazepines (BZD, BDZ, BZs), colloquially known as "benzos", are a class of central nervous system (CNS) depressant, depressant drugs whose core chemical structure is the fusion of a benzene ring and a diazepine ring. They are prescribed t ...
s are given to control seizures; as they also modulate GABA receptors they may potentially increase the effect of pyridoxine. Additionally MMH inhibits the chemical transformation of folic acid
Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing and ...
into its active form, folinic acid
Folinic acid, also known as leucovorin, is a medication used to decrease the toxic effects of methotrexate and pyrimethamine. It is also used in combination with 5-fluorouracil to treat colorectal cancer and pancreatic cancer, may be used to ...
, this can be treated by folinic acid given at 20–200 mg daily.
Long-term effects
ALS
Lagrange ''et al.'' presented in 2018 a link between life-long foraging for ''G. esculenta'' and amyotrophic lateral sclerosis
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or—in the United States—Lou Gehrig's disease (LGD), is a rare, Terminal illness, terminal neurodegenerative disease, neurodegenerative disorder that results i ...
(ALS) in French Alps populations. Similar ALS clusters possibly related to mushrooms are found near the Aosta Valley
The Aosta Valley ( ; ; ; or ), officially the Autonomous Region of Aosta Valley, is a mountainous Regions of Italy#Autonomous regions with special statute, autonomous region in northwestern Italy. It is bordered by Auvergne-Rhône-Alpes, Fr ...
(Italy), in Sardinia
Sardinia ( ; ; ) is the Mediterranean islands#By area, second-largest island in the Mediterranean Sea, after Sicily, and one of the Regions of Italy, twenty regions of Italy. It is located west of the Italian Peninsula, north of Tunisia an ...
, and in Michigan
Michigan ( ) is a peninsular U.S. state, state in the Great Lakes region, Great Lakes region of the Upper Midwest, Upper Midwestern United States. It shares water and land boundaries with Minnesota to the northwest, Wisconsin to the west, ...
.
Carcinogenicity
Monomethylhydrazine, gyromitrin, raw ''Gyromitra esculenta'', and ''N''-methyl-''N''-formylhydrazine have been shown to be carcinogen
A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...
ic in experimental animals. Although ''Gyromitra esculenta'' has not been observed to cause cancer in humans, it is possible there is a carcinogenic risk for people who ingest these types of mushrooms. Even small amounts may have a carcinogenic effect. At least 11 different hydrazones have been isolated from ''G. esculenta'', and it is not known if all potential carcinogens can be completely removed by parboiling.
Consumption
Despite its recognized toxicity, ''Gyromitra esculenta'' is marketed and consumed in several countries or states in Europe and North America. It was previously consumed in Germany, with fungi picked in and exported from Poland
Poland, officially the Republic of Poland, is a country in Central Europe. It extends from the Baltic Sea in the north to the Sudetes and Carpathian Mountains in the south, bordered by Lithuania and Russia to the northeast, Belarus and Ukrai ...
; more recently, however, Germany and Switzerland
Switzerland, officially the Swiss Confederation, is a landlocked country located in west-central Europe. It is bordered by Italy to the south, France to the west, Germany to the north, and Austria and Liechtenstein to the east. Switzerland ...
discouraged consumption by prohibiting its sale. Similarly in Sweden
Sweden, formally the Kingdom of Sweden, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. It borders Norway to the west and north, and Finland to the east. At , Sweden is the largest Nordic count ...
, the Swedish National Food Administration warns that it is not fit for human consumption, and restricts purchase of fresh mushrooms to restaurants alone. The mushroom is still highly regarded and consumed in Bulgaria
Bulgaria, officially the Republic of Bulgaria, is a country in Southeast Europe. It is situated on the eastern portion of the Balkans directly south of the Danube river and west of the Black Sea. Bulgaria is bordered by Greece and Turkey t ...
, being sold in markets and picked for export there. In some countries such as Spain, especially in the eastern Pyrenees
The Pyrenees are a mountain range straddling the border of France and Spain. They extend nearly from their union with the Cantabrian Mountains to Cap de Creus on the Mediterranean coast, reaching a maximum elevation of at the peak of Aneto. ...
, they are traditionally considered a delicacy, and many people report consuming them for many years with no ill effects. Despite this, the false morel is listed as hazardous in official mushroom lists published by the Catalan Government and sale to the public is prohibited throughout Spain. Outside of Europe, ''G. esculenta'' is consumed in the Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...
region and some western states in the United States.
Selling and purchasing fresh false morels is legal in Finland, where it is highly regarded. However, the mushrooms are required by law to be accompanied with a warning that they are poisonous and legally prescribed preparation instructions. False morels are also sold prepared and canned, in which case they are ready to be used. Official figures from the Finnish Ministry of Agriculture and Forestry report a total amount of false morels sold in Finland of 21.9 tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1,000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton in the United States to distinguish it from the non-metric units of the s ...
s in 2006 and 32.7 tonnes, noted as being above average, in 2007. In 2002, the Finnish Food Safety Authority estimated annual consumption of false morels to be hundreds of tonnes in plentiful years. In Finnish cuisine
Finnish cuisine is notable for generally combining traditional country fare and ''haute cuisine'' with contemporary continental-style cooking. Fish (food), Fish and meat (usually pork, beef or reindeer) play a prominent role in traditional Finl ...
, false morels may be cooked in an omelette
An omelette (sometimes omelet in American English; see spelling differences) is a dish made from eggs (usually chicken eggs), fried with butter or oil in a frying pan. It is a common practice for an omelette to include fillings such as chiv ...
, or gently sautéed in butter in a saucepan, flour and milk added to make a béchamel sauce
Béchamel sauce or Biratta cream (, ) is one of the mother sauces of French cuisine, made from a white roux (butter and flour) and milk, seasoned with ground nutmeg.
Origin
The first recipe of a sauce similar to béchamel is in the book by ...
, or pie filling. Alternatively, more fluid can be added for a false morel soup. Typical condiments added for flavour include parsley
Parsley, or garden parsley (''Petroselinum crispum''), is a species of flowering plant in the family Apiaceae that is native to Greece, Morocco and the former Yugoslavia. It has been introduced and naturalisation (biology), naturalized in Eur ...
, chives
Chives, scientific name ''Allium schoenoprasum'', is a species of flowering plant in the family Amaryllidaceae.
A perennial plant, ''A. schoenoprasum'' is widespread in nature across much of Eurasia and North America. It is the only spe ...
, dill
Dill (''Anethum graveolens'') is an annual herb in the celery family Apiaceae. It is native to North Africa, Iran, and the Arabian Peninsula; it is grown widely in Eurasia, where its leaves and seeds are used as a herb or spice for flavouring ...
and black pepper
Black pepper (''Piper nigrum'') is a flowering vine in the family Piperaceae, cultivated for its fruit (the peppercorn), which is usually dried and used as a spice and seasoning. The fruit is a drupe (stonefruit) which is about in diameter ...
.
While cooking the fungus removes (most of) the toxins, the cook can become poisoned by the hydrazine
Hydrazine is an inorganic compound with the chemical formula . It is a simple pnictogen hydride, and is a colourless flammable liquid with an ammonia-like odour. Hydrazine is highly hazardous unless handled in solution as, for example, hydraz ...
fumes given off by cooking.
Controversies
In 2015, Swedish chef caused a controversy when he prepared a dish with ''Gyromitra esculenta'' in a TV show. Mushroom expert Monica Svensson criticized him for including it, because monomethylhydrazine
Monomethylhydrazine (MMH) is a highly toxic, volatile hydrazine derivative with the chemical formula . It is used as a rocket propellant in bipropellant rocket engines because it is hypergolic with various oxidizers such as nitrogen tetroxide () ...
is a known carcinogen and there is a risk that inexperienced people might misinterpret the recipe and omit the steps that reduce the toxicity level. She also expressed criticism to Per Morberg for similar reasons. Paul Svensson said that he was not aware of the carcinogenic effects and apologized afterwards, and he promised to remove ''Gyromitra'' from his dishes.
Preparation
Most of the gyromitrin must be removed to render false morels edible. The recommended procedure involves either first drying and then boiling the mushrooms, or boiling the fresh mushrooms directly. To prepare fresh mushroom it is recommended that they are cut into small pieces and parboiled
Parboiling (or leaching) is the partial or semi boiling of food as the first step in cooking. The word is from the Old French ''parbouillir'', 'to boil thoroughly' but by mistaken association with "part", it has acquired this definition.
The w ...
twice in copious amounts of water, at least three parts water to one part chopped mushrooms, for at least five minutes, after each boiling the mushroom should be rinsed thoroughly in clean water. Each round of parboiling reduces the free gyromitrin contents to a tenth. Significant amounts of gyromitrin are retained in the internal structure of the mushroom even after boiling. After 3 rounds of boiling for 5 minutes and discarding the water, the gyromitrin content is reduced to 6-15% of the original. After 5 rounds, this content is reduced to 7%. The gyromitrin is leached into the water where it will remain, therefore the parboiling water must be discarded and replaced with fresh water after each round
Round or rounds may refer to:
Mathematics and science
* Having no sharp corners, as an ellipse, circle, or sphere
* Rounding, reducing the number of significant figures in a number
* Round number, ending with one or more zeroes
* Round (crypt ...
of boiling. However, it is still recommended that the mushroom be boiled after drying.
MMH boils at and thus readily vaporizes into the air when water containing fresh false morels is boiled. If boiling the mushrooms indoors, care should be taken to ensure adequate ventilation, and, if symptoms of monomethylhydrazine poisoning appear, immediately open all windows and move outside to seek fresh air. Even after boiling, small amounts of gyromitrin and other hydrazine derivatives remain in the mushrooms. Given the possibility of accumulation of toxins, repeated consumption is not recommended.
Prospects for cultivation
Strains with much lower concentrations of gyromitrin have been discovered, and the fungus has been successfully grown to fruiting in culture. Thus there is scope for future research into cultivation of safer strains.
See also
* List of deadly fungi
References
; General
*
*
; Specific
External links
"''Gyromitra esculenta'', one of the false morels"
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Discinaceae
Poisonous fungi
Fungi of North America
Fungi of Europe
Fungi described in 1800
Taxa named by Christiaan Hendrik Persoon
Fungus species