By KAZUHIKO MATSUNAGA/ Staff Writer
November 14, 2025 at 17:11 JST
Poisonous "tsukiyotake" (Omphalotus guepiniformis) mushrooms (Provided by Wakayama Prefectural Museum of Natural History)
Artificial intelligence should not be used to decide if it is safe to eat mushrooms foraged during a mountain hike beneath the autumn leaves, according to the health ministry.
A pamphlet on the ministry's website carries a broader warning to, “Limit the use of internet image search results as reference only, and do not use them for mushroom identification.”
One unfortunate recent case involved a man in his 70s from Wakayama Prefecture coming down with food poisoning after eating mushrooms he picked in the mountains of Shimokitayama, Nara Prefecture.
The city said the man used the AI function on his electronic device to identify his haul, grilling and eating it after the AI incorrectly told him they were shiitake and "hiratake" oyster mushrooms.
He began vomiting about 30 minutes later and was temporarily hospitalized.
An examination of the mushrooms at the Wakayama Prefectural Museum of Natural History located in Kainan, Wakayama Prefecture, revealed that they were poisonous "tsukiyotake" (Omphalotus guepiniformis).
The city confirmed the man had food poisoning after detecting illudin S, a toxin characteristic of tsukiyotake. This species of mushroom commonly grows on fallen or dead beech trees, and its color and shape do resemble that of shiitake and oyster mushrooms.
Concerning Wakayama Prefecture, tsukiyotake can be found in Tanabe's Ryujin district near the summit of Mount Gomadanzan at an elevation of 1,372 meters. These mushrooms also glow bluish-white in the dark.
Shinichi Kawakami, 59, a senior curator at the museum and an expert on fungi and mushrooms, warned that, “Tsukiyotake looks beautiful at night, but you must never eat it.”
He also noted that wild mushrooms can carry harmful bacteria.
“It’s important not to eat mushrooms based on your own judgment and to consult an expert. AI can sometimes make incorrect determinations,” Kawakami said.
This is not the first instance of mistaken identity. According to Wakayama Prefecture and other sources, there have been at least two confirmed cases of food poisoning caused by eating tsukiyotake in the prefecture since 2000.
The health ministry is urging the public to be cautious of not only mistaking this particular mushroom for an edible variety, but several others as well.
"Kusaurabenitake" (Entoloma rhodopolium or the wood pinkgill) can be easily mistaken for the familiar "hon-shimeji" (Lyophyllum shimeji), which are ubiquitous in supermarkets.
"Tengutake" (Amanita pantherina or panther cap) and "dokutsurutake" (Amanita virosa) are also mentioned, as is the highly poisonous "kaentake" (Podostroma cornu-damae or poison fire coral); as the name suggests, it is often orange or red with a shape similar to a finger. Merely touching one can cause skin inflammation.
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