Michelle Dickenson: Nanotechnologist on the harmful impacts of consuming 'death cap' mushrooms

Last week, three people died and one is still in a critical condition in a Melbourne hospital after eating a beef wellington pie – while the official cause of death has not been confirmed, their deaths are suspected to be from mushroom poisoning. 

The mushroom in question – known as the ‘death cap’ mushroom, doesn’t have the typical red and yellow colours of other toxic items found in nature, instead it is white and plain looking – similar to an ordinary field mushroom.  

While nature usually warns you that something is toxic with a bitter taste, death cap mushrooms have been described by those who have been poisoned by it as the tastiest mushroom they’ve ever eaten. 

It only takes a few mouthfuls of death cap mushroom to kill, so how is it so deadly? 

After chewing and swallowing the mushroom, the toxins within the mushroom, known as amatoxins are released. These are absorbed in the gut and then travel to the liver. The amatoxin binds to an enzyme in the liver responsible for making new proteins which disables the cells and stops them from working resulting in liver failure within 48 hours. 

The now poisoned liver cells are also responsible for making bile, and this amatoxin containing bile is concentrated in the gall bladder. After every meal, the gall bladder releases the amatoxin containing bile into the gut, which then travel through the small intestine with the food and are reabsorbed back into the liver where the poisoning cycle then repeats. 

Some of the absorbed amatoxins head to the kidneys which poisons the cells there too causing kidney failure. Once in kidney failure, rapid organ failure quickly occurs afterwards resulting in coma and then death. 

One of the reasons for it’s high fatality rate is that symptoms from the poisoning typically aren’t experienced until at least 6 and up to 24 hours after ingestion so most people don’t know they have been poisoned until it’s too late. Also the initial symptoms are abdominal cramps, vomiting and diarrhoea which makes it easy to mistake the poisoning with something else like stomach flu. 

In New Zealand, death cap mushrooms grow around oak and chestnut trees and the poisonous amatoxin is heat stable remaining toxic even if the mushroom is cooked. 

 The easiest way to protect yourself is to not eat wild mushrooms unless you have some expertise in what the death cap (and other poisonous mushrooms) look like. 

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