Mushrooms have been consumed by people all over the world for centuries. A staple in the Asian diet, mushrooms are believed to have nutritional and medicinal value. It wasn’t long before the lethal toxicity of certain mushroom species was discovered.

Hong Kong is one of the regions in Asia which has a huge consumption of mushrooms. However, according to the Hong Kong Poison Information Centre, 67 cases of mushroom poisoning were reported from 1 July 2005 to 30 June 2015, and the number is on the rise.

Here we revisit some common myths to prevent such poisoning cases from happening any longer.

1. Purchased mushrooms are 100% safe


While consumers might learn the danger of picking and consuming mushrooms from the wild, most of them might not be aware of the possible risk of purchased mushrooms.

In February, a Hong Kong family presented vomiting and diarrhoea after they consumed mushrooms which they had bought from a store between mid-November and early December last year.

“We believe what is available for sale should be edible,” said Dr Man-Li Tse, Hospital Authority Consultant. “But there could be a quality problem during harvesting in that both edible and inedible species were mixed together,” he added.

Although the mushrooms are purchased from store, Dr Tse emphasised quality of the mushroom can be varied. He specifically recalled his team found worms, dead flies and soil debris on the porcini samples provided by patients who sought medical help.

Apart from the source of mushrooms which might contain toxins, mushrooms are also likely to be exposed to an unsafe level of toxins when an error happens during the packaging procedures.

To prevent, Dr Chi-Keung Chan, Hospital Authority Associate Consultant, recommended consumers purchase mushroom from reputable stores only. He also warned consumers to watch out signs which indicate that the mushrooms are possibly contaminated. “There could be quality problems if the mushrooms are broken into pieces…or if there were insects or soil,” Chan explained.

2. Mushrooms can be rendered non-toxic through cooking


Since most viruses in food can be killed by heating up through cooking, some consumers have the false belief that toxic mushrooms picked from the wild can be rendered non-toxic through cooking.

While it might be true that longer cooking times could reduce the toxin levels for some of the mushrooms, mushroom toxins are indeed resistant to heat and cannot rendered non-toxic for a majority of the mushroom species.

One of the deadly classes of toxin which resist changes due to heat is Amatoxins, which can stay latent in human from 6 hours to 2 days after consumption without showing any poisoning symptoms, which might delay the victim in seeking immediate medical attention. Even if the victim can survive through the initial symptoms of nausea, vomiting and abdominal pain, the toxin can result in liver failure shortly afterwards and causing death.

Examples of poisonous wild mushrooms that can be found in Hong Kong. Amanita phalloides contains amatoxins while Panaeolus retirugis contains psilocin. (Photo by courtesy of Professor Shu-Ting Chang, Emeritus Professor of Biology at The Chinese University of Hong Kong)
Examples of poisonous wild mushrooms that can be found in Hong Kong. Amanita phalloides contains amatoxins while Panaeolus retirugis contains psilocin. (Photo by courtesy of Professor Shu-Ting Chang, Emeritus Professor of Biology at The Chinese University of Hong Kong)

In 2013, a couple fell seriously ill after consuming wild Amanita farinosa, one of the most toxic species which contains Amatoxins in Hong Kong. While both have suffered severe liver damage, the men managed to survive with medical treatment and his wife fortunately received a timely liver transplant which saved her life.

3. Toxic mushrooms can be identified with colours


Many believe mushrooms are more poisonous if they appear more colourful. However, this is not the case and identifying poisonous mushrooms through their colour is not at all reliable. Indeed, toxic and non-toxic species of mushrooms can look very similar and distinguishing between both requires the expertise of mycologists.

These mushrooms which appear only white in colour are Amanita farinosa, one of the most toxic species which contains Amatoxins in Hong Kong. (Photo credit: Wikipedia)
These mushrooms which appear only white in colour are Amanita farinosa, one of the most toxic species which contains Amatoxins in Hong Kong. (Photo credit: Wikipedia)

Other ways which are said to be able to identify poisonous mushrooms such as shape, taste and reactions with silver also do not correlate with mushroom toxicity. Since 90% of wild mushrooms in Hong Kong are inedible or poisonous, the public is advised not to take the risk and collect or consume mushrooms from the wild. MIMS

Read more:
5 more common food myths busted
Are all natural foods safer? The myth of healthy natural foods
5 common foods that may interact with medications
Turn your favourite junk food into healthy indulgences

Sources:
http://www.cfs.gov.hk/english/multimedia/multimedia_pub/multimedia_pub_fsf_90_02.html
http://www.hkmj.org/abstracts/v22n2/124.htm
http://www.scmp.com/news/hong-kong/health-environment/article/2072448/better-mushroom-quality-urged-hong-kong-poisonings
http://www.scmp.com/news/hong-kong/education-community/article/1936993/ding-ding-mushrooms-surprise-commuters-hong-kongs
https://en.wikipedia.org/wiki/Mushroom_poisoning
http://www.scmp.com/news/hong-kong/article/1224013/wild-fungus-dish-left-hikers-near-death