The Dangers of Gyromitra esculenta
or, What’s good for the goose, isn’t necessarily good for the
gander.
By Jim Dunham
Gyromitra esculenta, also
called the beefsteak, or brain, mushroom contains ethylidene gyromitrin.
Ethylidene gyromitrin may be converted to N-methyl-N-formylhydrazine
(MFH) after the mushroom is eaten. MFH may then be converted to the
toxic monomethylhydrazine (MMH) or into a much safer metabolic form,
called 1-acetyl-2-methy-2-formylhydrazine (Ac-MFH).
What’s important to note is that certain people’s systems convert MFH
into Ac-MFH fairly rapidly. These are the
geese. What about the ganders?
Well, they convert MFH into Ac-MFH much more slowly. This means that
their systems end up with a much larger amount of much more of the highly
toxic MMH. Now the gander wishes that he hadn’t come to the picnic
after all. It’s also important to note
that if there are young geese and ganders at the picnic, then they are in
greater danger than the oldsters. Because
their body weight is less than the adults, if they eat the same number of
mushrooms then the percentage of toxins in their systems is much
higher. This is true regardless of their ability to convert MFH into
Ac-MFH. Because this example is greatly
over-simplified, interested readers are referred to A Morel Hunter’s
Companion, by Nancy Weber, pages 64-69.
Spores Afield - May 2000
More on Gyromitra
by Marilyn Shaw,
Toxicology chairperson
The accompanying discussion of the development
of various toxins associated with Gyromitra esculenta is interesting, but
it should not effect your decision to on whether or not to eat any
gyromitra. Dr. Weber prefaces this discussion with, “With this
background, we can TRY (emphasis mine) to explain some of the apparent
peculiarities of poisoning by the beefsteak morel.” She ends the
paragraph with, “There is no convenient way to tell whether one is “fast”
or “slow” acetylator and thus no way to judge tolerances for toxins in
the beefsteak morel.” It should be understood that, just because
one has eaten these mushrooms without ill effect in the past does not
settle the question one way or the other. It is well known that
people can eat them for years, then, for no apparent reason, get sick and
even die. The mortality rate among those who become ill is about
14%.
Dr Weber goes on to state, “We cannot in good
conscience, however, recommend eating any species of Gyromitra until more
detailed information on fruiting body composition is available. McIlvaine
and Macadam (1902) were perhaps ahead of their time when they wrote of the
beefsteak morel: “It is not probable that in our great food-giving
country anyone will be narrowed to G. esculenta for a meal. Until
such an emergency arrives, the species would be better left alone.”
Their advice could well be extended to cover the entire genus.”
Considering that Charles McIlvaine, the professor of the
quintessential “cast iron stomach”, was reported to have personally
tested (by eating) something well over 700 species, it would seem wise to
follow his advice.
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