Shaggy Parasol edibility, toxicity, and biological mechanisms.

[mushroomfadguy]

Hi guys,

I'm a bit confused and could use some guidance around the edibility of the Shaggy Parasol, which in the UK generally means Chlorophyllum rhacodes.

This local website (https://www.wildfooduk.com/mushroom-guide/shaggy-parasol/) suggests it is "inedible" due to an apparent 1/25 chance of "severe gastric upsets", yet consumption is not necessarily ruled out, with one needing to eat a small amount, "wait 24 hours to see if there is a reaction" and then go on from there.

A second source (https://www.foragingcoursecompany.co.uk/foraging-guide-shaggy-parasol) states:

Quote

"A good tasting mushroom that must be thoroughly cooked before consumption. It is thought to be toxic when raw. Despite its edibility, a small proportion of people have a gastric reaction to Shaggy Parasols."

According to another reputable source (https://www.first-nature.com/fungi/chlorophyllum-rhacodes.php):

Quote

 

The taxonomy of this species has changed recently. As a result of molecular studies (DNA analysis), in 2003 the genus Macrolepiota was split up and the Shaggy Parasol was transferred to the genus Chlorophyllum, where it resides with other poisonous parasol-like mushrooms. (Macrolepiota procera, the popular edible Parasol, stayed put!)"

"Many books and websites state that this is a good edible mushroom, but the Shaggy Parasol has been known to cause serious illness in some people and so in our opinion picking it to eat, intentionally or otherwise, should be avoided.

 

The latter seems to be confirmed with dozens of youtube videos where people find these things, verify them to be edible in field books, and then cook them up describing how wonderful they are.

So I wanted to explore a bit deeper on the subject before potentially taking the 1/25 risk myself and sampling the few I'd collected yesterday (don't worry the spores are white and we don't have C. molybdites in the UK). Specifically, I wanted to know the biochemical mechanisms thought to be behind this 4% chance of severe gastric upset so I brought up Google Scholar, searched for "Chlorophyllum rhacodes toxicity" and within an hour or so couldn't find anything remotely relevant so I wanted to know what all the fuss was based upon. I mean, where does the apparent data come from and who is interpreting it, and where does a forager go to find out these things?

Without being able to find a proper study, it seems like any of the below explanations might be plausible:

1) Stem is thought to be tough and best avoided. Maybe people are just getting constipation/gasses (fried Grifola frondosa nearly incapacitated my partner for 24h).

2) 1/25 people eat slightly rotten specimen or possibly those containing some toxic insects.

3) Second source emphasizes the need for cooking, perhaps 1/25 people don't cook it long enough.

4) 1/25 people confuse it for another mushroom entirely, possibly some rare unidentified missing link between C. molybdites and C. rhacodes. 

I wouldn't mind giving these a go, if I could be confident that some lasting effect on my liver were not at stake here, a 4% risk of constipation I can handle. Be great to know what others think and just some general advice on where to get answers to specific questions like this when Google Scholar fails you. 

Many thanks,

Richard

 

[JOHNY]

I have eaten "Parasol" type mushrooms twice, growing in Ontario, just north of Minnesota. They might be called C. rachodes but like many morphologically similar mushrooms in Europe vs.  North America, they may have enough differences in DNA to be called different species.

I would eat them again. They were delicious.

As data and anecdotes accumulate, especially on the Internet, almost every species of mushroom can have a story associating it with toxic events.

Some people have idiosyncratic reactions that are rare: example, a neighbour friend who has definite GI reactions to Wine Caps (S. rugosoannulata). She finally realised what was happening after five separate nights of nausea and vomiting a few years ago.

Others can develop reactions after many years of exposure: example, father of a co-worker can no longer eat Morels after having no trouble for 50 years. No matter how long and hot they cook them, he suffers ++GI reaction.

Then there are "once only events" like the cluster of lethal encephalopathy that occurred in Japan 25 years ago from eating Angel Wings (P. porrigens). But it only happened one year and everyone was on dialysis (or extreme advanced renal failure) before eating them. But now, all sources say don't eat them even though people ate them for centuries and still do.

People have eaten various Leccinum species for centuries, but even on this forum there are topic threads that suggest caution due to reports of toxicity.

Sometimes, I think we can have too much information. The eternal persistence of any Internet postings can be useful but I believe can also escalate unnecessary fears as hyper-rare anecdotes accumulate and are repeated and eventually become accepted fact

Ultimately, it your decision to eat or not, your Shaggy Parasols. The cautious approach of eating one bite, wait a few hours...have some more, wait until the next day and eat the rest is a sensible approach every time you try a new mushroom

 

[Kevin Hoover]

And mushrooms that cause gastric distress do not necessarily have the same toxins as the Aminta family does, and may not necessarily harm the liver.

[vitog]

Negative reactions to various mushrooms do not necessarily indicate the presence of any toxins.  People experiencing gastric upset from eating Shaggy Parasols may be allergic to them, just like anyone can be allergic to just about any food item.

[mushroomfadguy]

Hey guys, thanks a lot for this, so it seems there's a lot of agreement with the perspective that it might well be just a lot of hot air. It also seems from people's use of words like "necessarily" there remains room for the possibility that these anecdotes amount to something a more cautious individual might want to avoid.

To update my sense of the "literature" after spending a while on this now it seems to me reasonably likely that any gastric issues caused from eating Chlorophyllum rhacodes is caused by the same phenomena as C. molybdites, only to a lesser degree. I base this entirely on the similarity of symptoms (I am told cramps, diarrhoea, and vomiting are equally relevant so it's probably not just constipation from fibrous material) and the fact that in 2003 (as the third source I quoted suggests) C. rhacodes was moved out of the Macrolepiota genus and into Chlorophyllum based on genetic similarity to species like C. molybdites. I also note that some people can apparently tolerate C. molybdites greater than others as described in the following random website (https://whyfarmit.com/chlorophyllum-molybdites/) which also suggests C. rhacodes might share the same "toxins" only to a lesser degree, and speculates on some possible mechanisms for the variability like differences in individual's stomach acid but ultimately describes the culprit toxin to be unidentified.

If you bring up Google Scholar and search for "Chlorophyllum molybdites literature review" (since 2017) there's not a whole lot but some dude's thesis pops up (http://studentsrepo.um.edu.my/9550/9/rabeah.pdf) where in the abstract it says the following:

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"C. molybdites from the family of Agaricaceae is a poisonous mushroom often involved in poisoning cases throughout the world. This fungi is known to produce the toxic components such as a toxic protein, molybdophyllysin."

If you scroll down to part "2.3 Chlorophyllum molybdites" the subject is expanded upon and some references cited.

Apparently some guy was able to get an "extract" from the mushroom and found it to be unharmful for mice when ingested but killed them when injected (Floch et al 1966) and that this meant whatever was responsible might weaken over time (possibly relevant to the need for cooking?). This was also found to be the case in chickens and dogs (Eilers & Nelson 1974) who also noted reduced blood pressure. Falade et al 2008 apparently looked at the chemical composition of the shroom and found it to be higher in tannins and trypsin. Then it delves into the discovery of a protein called molybdophyllysin which apparently has proteolytic activity (the ability to break down proteins according to google) and the rest is too complicated for me but doesn't look any more reassuring (but it might be able to destroy stomach cancer cells).

I think I'm going to hold for a Macrolepiota tbh while they figure this one out and I apologize if I've put anyone off they sounded really tasty. Life is pointless without experiences and this sounds like it would have (96% of the time) been a good one, I'm just a bit of a pussy when it comes to these things. Happy mushroom season everyone. 

[ontoast]

Too late for original question but I wanted to share my experience for anyone finding this post. I have a food intolerance to shaggy parasol. I won't say allergy as I didn't go into anaphylactic shock. Vomiting, cramping, diarrhoea for 24 hours.  I collected the mushrooms on a walk with a very well known fungus expert. I won't name who because we were all given the warning that anyone could be allergic to various mushrooms, but I didn't think anything of it, I was not allergic to anything else, I'd eaten other wild mushrooms before with no problem. I'd eaten giant puff balls and ink caps. I'd eaten the other type of parasol Macrolepiota procera. So it is entirely my own fault I didn't heed the warning. I only mention the expert to highlight I am really confident we ID'd them correctly. I also looked them up in a book  and confirmed the id when I got home to show my husband, because I was geeking out on fungi knowledge that day. 

I collected them early morning. I fried them up and husband and I ate them on toast for brunch. They were absolutely delicious. Husband was completely fine, after a few hours I was in bed with a sick bucket. I lived to tell the tale, no permanent damage. I have since had the same reaction to the Mycoprotein in Quorn meat substitute. So I think it is a me problem, not the species itself. I would totally try other wild fungi, but I would definitely do a mini test first. 

[Kevin Hoover]

I think the species might differ somewhat between the UK and US.  I talked to Greg Marley about shaggy parasols and he hadn’t heard anything. And is very active in the mushroom poison control in his state.

[ZUnit]

There is also the fact that 80% of all mushroom poisonings come from improper cooking/storage or the mushrooms being eaten past prime. So all these tales of some people having reactions to edible mushrooms could be a mix between this and personal allergies/intolerance. People go out foraging for specific mushrooms and then find them all buggy and deteriorating and eat them anyway because they are so excited to of found what they were looking for. This or they find something that looks similar and don't do their due diligence to properly identify it and then blame the edible mushroom they thought it was when they get sick. 

Or some people are picking them from parks and yards where chemicals are being sprayed. I got sick from eating a perfect/super fresh Lions Mane once and I believe it was because it or the area near it was sprayed with chemicals of some sort and the Lions Mane had absorbed some of them. Pesticides, herbicides, fungicides, weed killer, heavy metals, who knows...