Some natural foods, such as poisonous mushrooms, are not edible.

1. Poisonous Mushrooms
How can you identify poisonous mushrooms?
Poisonous mushroom poisoning has ranked first in the number of food poisoning deaths nationwide for many years. Poisonous mushroom poisoning mostly occurs during the rainy season when wild poisonous mushrooms grow, and cases are usually sporadic. In addition, eating dried poisonous mushrooms can also cause poisoning. Most victims of poisonous mushroom poisoning are rural residents. They enjoy picking and eating wild mushrooms, but often rely on experience rather than having genuine knowledge or ability to distinguish poisonous mushrooms.
Even very professional individuals can hardly guarantee accurate identification of whether a mushroom is poisonous, let alone ordinary people. Some say “the prettier the mushroom, the more poisonous it is,” but this claim is actually unreliable. To determine whether a wild mushroom is poisonous, one needs to be familiar with the types of mushrooms and their growing environments, and consider these factors comprehensively.
The claim that “the prettier the mushroom, the more poisonous it is” is actually unreliable.

How toxic are poisonous mushrooms?
China has about 180 species of poisonous mushrooms, at least 30 of which can be fatal. Common ones include the brown-scale little umbrella, the flesh-brown-scale little umbrella, the white poison umbrella, the scaly-stem white poison umbrella, the poison umbrella, the remnant-support spotted poison umbrella, the poison powder-fold mushroom, the autumn-born helmet-spore umbrella, the wrapped-foot black-fold umbrella, the deer flower fungus, and so on.
Symptoms of poisonous mushroom poisoning can be divided into six types: gastrointestinal, neuropsychiatric, hemolytic, organ-damaging, respiratory and circulatory failure, and photosensitive dermatitis. Among them, liver-damaging type is the most dangerous. White poison umbrella poisoning falls into this category; just about 50 grams of white poison umbrella is enough to kill an adult. Its toxins severely damage the liver, kidneys, vascular endothelial cells, and central nervous system, ultimately leading to multi-organ failure and death, with a mortality rate as high as 90%–100%. In March 2000, migrant workers in Guangzhou’s Tianlu Lake Park in Baiyun District picked white poison umbrellas, cooked them, and ate them. As a result, all nine who ate them got poisoned, and eight died within just a few days. The one person who was saved later also passed away half a year later.
Neuropsychiatric-type poisoning is the most bizarre reaction to poisonous mushrooms. Some toxins can cause hallucinations similar to those induced by drugs. Some poisoned individuals become extremely euphoric, singing and dancing wildly; others become unpredictably moody like drunkards; some appear dazed, as if in a dreamlike state. Neuropsychiatric-type poisoning has a lower fatality rate, but some poisonous mushrooms are extremely toxic and have no specific treatment, resulting in a 100% mortality rate.

“Hand-touch green” causes “Lilliputian hallucination syndrome”
Yunnan, with its spring-like climate all year round, is a uniquely favorable environment for producing various types of fungi. Most are edible, but many are poisonous. I heard many stories about poisonous mushrooms in Yunnan. A local told me that every year around May and June, he would stir-fry a local fungus called “hand-touch green.” If cooked just right—neither too raw nor too well-done—it would cause hallucinations, like watching a fairy-tale movie about Lilliput, where all kinds of little people, cars, and animals appear before your eyes. When you reach out to grab them, the little people run away. You may also see many colorful little balls and sticks floating in the sky, as if you’re truly experiencing a “Lilliput adventure.” This is medically known as “Lilliputian hallucination syndrome.” He showed me the “hand-touch green” mushroom, which was really beautiful—vividly colored with a red-yellow cap and yellow stem, absolutely gorgeous. It’s called “hand-touch green” because if you touch it hard with your hand, it immediately turns bluish-green. Later, I looked up information and found out its scientific name is Boletus magnificus or Boletus speciosus. Such a beautiful name is indeed fitting, but unfortunately, beneath its attractive appearance lies a hallucinogenic toxin.

2. Legumes
According to statistics, among collective food poisoning incidents caused by toxic animals and plants, many are due to undercooked legumes. Such incidents are more common in autumn, the harvest season for legumes.
Raw green beans contain saponins that strongly irritate the human digestive tract, can cause hemorrhagic inflammation, and have a hemolytic effect on red blood cells. In addition, raw green beans also contain hemagglutinin, which has a red blood cell-agglutinating effect. If cooking does not thoroughly heat the beans, the toxic components remain unbroken, and eating them may lead to poisoning.
Raw flat beans also contain saponins and hemagglutinin. If flat beans are not thoroughly heated, they will taste tough and have a strong beany flavor; meanwhile, the toxins in the beans are not eliminated, making them highly prone to causing poisoning if consumed. Especially in dishes like flat bean-filled dumplings, cold mixed blanched crisp flat beans, and stir-fried flat beans, due to short heating times or insufficient temperatures, the toxins are hard to break down. Eating such undercooked flat beans can cause food poisoning within a short time (1–3 hours), with symptoms such as nausea, vomiting, and diarrhea.
Legumes such as green beans, flat beans, red kidney beans, and white kidney beans can cause poisoning if consumed raw or undercooked.

3. Seeds and Pits
Fruits such as apples, peaches, apricots, pears, plums, cherries, and others have flesh that is non-toxic, but their pits and seeds contain cyanogenic glycosides. If you eat the fresh pits or seeds of these fruits, the cyanogenic glycosides inside can convert into hydrogen cyanide. Hydrogen cyanide is a highly toxic substance that can cause death by paralyzing the respiratory center. Children are the most vulnerable; just eating a few seeds or pits may lead to cyanide poisoning.

Eating raw almonds can cause fatal poisoning
Cases of poisoning from cyanogenic plants have been reported both domestically and internationally, with bitter almond poisoning being the most common. Symptoms of bitter almond poisoning often include a bitter taste in the mouth, drooling, headache, dizziness, nausea, vomiting, palpitations, increased pulse, cyanosis. Patients’ breath may smell of bitter almonds, and they may exhibit dilated pupils, loss of light reflex, clenched jaws, generalized intermittent spasms, and eventually die from respiratory paralysis or cardiac arrest. In addition, consuming large amounts of raw sweet almonds can also lead to poisoning.

4. Cassava
Cassava is the edible root of cassava plants. It contains natural toxins such as cyanogenic glycosides, with bitter cassava having higher toxin levels than sweet cassava. Eating raw or undercooked cassava can cause the cyanogenic glycosides to convert into hydrogen cyanide, leading to food poisoning. Symptoms of cyanide poisoning can appear within minutes and include throat constriction, nausea, vomiting, headache, and in severe cases, death.

5. Bamboo Shoots
Bamboo shoots have toxicity similar to that of cassava. Fresh bamboo shoots also contain natural cyanogenic glycosides, and eating raw or undercooked bamboo shoots may also cause food poisoning.

6. Fresh Daylilies
Fresh daylilies, also known as golden needles, forget-me-not flowers, or daylily flowers, are the flowers of a plant harvested before blooming. Fresh daylilies are generally not suitable for raw consumption. This is because the roots and flowers of fresh daylilies contain colchicine. This alkaloid is non-toxic in itself, but once it enters the gastrointestinal tract, it oxidizes into colchicine, which strongly irritates the gastrointestinal and absorption systems. Adults who consume 0.1–0.2 milligrams of colchicine at one time may experience poisoning. Once poisoned, symptoms such as dry throat, heartburn, thirst, nausea, vomiting, abdominal pain, and diarrhea may occur, and in severe cases, bloody stools, bloody urine, or urinary retention may appear. Ingesting 20 milligrams of colchicine at one time can be fatal. The incubation period is generally between half an hour and four hours.

7. Potatoes
The toxic components in potatoes are primarily solanine. Under normal circumstances, the solanine content in potatoes is very low and does not have adverse effects on humans. During storage, when potato tubers are exposed to light, their skin gradually turns green—a phenomenon known as "greening." Potato greening occurs due to the production of chlorophyll and the simultaneous accumulation of solanine. Under light exposure, the degree of greening varies with storage temperature, with lower temperatures inhibiting greening. Therefore, the storage temperature of potatoes should not exceed 10°C, and they must be kept strictly away from light.
Once a potato sprouts, the solanine content in the sprout eyes and roots increases sharply, reaching 40–70 times the normal level. Ingesting just 0.2–0.4 grams of solanine can cause poisoning, with symptoms including an itchy or burning sensation in the throat, a burning or painful feeling in the upper abdomen, followed by gastrointestinal symptoms such as gastroenteritis, as well as dizziness, headache, mild consciousness impairment, and difficulty breathing. In severe cases, death may result from heart failure or respiratory center paralysis. Therefore, never eat potatoes that have turned green or sprouted.
Never eat potatoes that have turned green or sprouted.

8. Ginkgo Nuts
Ginkgo nuts are the fruit of the ginkgo tree and contain various plant toxins, primarily affecting the nervous system. Children are most susceptible to poisoning from consuming ginkgo nuts. Ginkgo nuts have acute toxicity. It has been reported that eating just 10–50 uncooked ginkgo nuts at one time can lead to acute poisoning. Poisoned individuals typically experience typical symptoms such as vomiting, restlessness, and persistent or clonic convulsions within 1–12 hours after ingestion. Severe cases may lead to loss of consciousness or even death.

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