Suggestion: introduction of bracken: bracken is also called longevity vegetable. It is a wild plant, known as the "king of mountain vegetables", which is produced in mountainous areas. Pteridium aquilinum is nutritious and contains carotene, vitamin C and various minerals. Pteridium aquilinum can be eaten fresh or pickled. Bashang area is also one of the producing areas of Pteridium aquilinum in China. Pteridium aquilinum is not only popular in China, but also praised by foreign guests. On the grassland, there are shallow hills and dense forests. There is a wild vegetable in the forest, which is light green and has thick stems. On one side of the stem, there are fine serrations and slightly curled leaves. The whole plant looks like a bird's wing, called the wing of a pheasant, which is very vivid. Brush a few, take it home, wash it and chop it up, then prepare a few pieces of fat meat and half a pot of water, and then add wild vegetables when the meat is rotten and the soup is fat. Drink soup after boiling, its delicious can not be expressed in words. Pteridium aquilinum: Also known as "Wunuo", also known as the leading dish, Pteridium aquilinum not only tastes fresh and smooth, but also has high nutritional value. Every 100g fresh product contains 0.43g of protein, 0.36g of fat, 3.6g of sugar and 0.45g of organic acid, and contains a variety of vitamins and minerals, which is several times to ten times that of ordinary cultivated vegetables, so it is enjoyed. Pteridium aquilinum has the functions of detoxifying, clearing away heat, moistening intestines, reducing qi and resolving phlegm. Can be used for treating hypertension, dizziness, insomnia, metrorrhagia, chronic arthritis, etc., and also has preventive effect on influenza. Pteridium aquilinum: Also known as "Wunuo", also known as the leading dish, Pteridium aquilinum not only tastes fresh and smooth, but also has high nutritional value. Every 100g fresh product contains 0.43g of protein, 0.36g of fat, 3.6g of sugar and 0.45g of organic acid, and contains a variety of vitamins and minerals, which is several times to ten times that of ordinary cultivated vegetables, so it is enjoyed. Pteridium aquilinum has the functions of detoxifying, clearing away heat, moistening intestines, reducing qi and resolving phlegm. Can be used for treating hypertension, dizziness, insomnia, metrorrhagia, chronic arthritis, etc., and also has preventive effect on influenza. Bracken contains carcinogens. Don't eat indiscriminately. Studies have shown that the cancer-related substances in bracken include phenyloxalic acid, fern lactam, flavanol, calamine and some substances similar to calamine. The content of these substances is the highest in rhizome, followed by leaves and petioles. According to the analysis of Japanese scholars and experts, it may be related to the Japanese habit of eating ferns. Scholars in China have found that cattle that have been feeding on bracken for a long time have leukemia. Feeding fern to sheep and quail can also induce tumors, with an incidence rate of 79%. Pteridium aquilinum can not only directly cause cancer, but also synergistically promote the growth of cancer that has already occurred. Carcinogens were also found in the milk of cows that ate bracken. Because small animals fed with this milk can induce intestinal cancer, renal cancer and bladder cancer, people who drink this milk are also at risk of cancer. Scientists' carcinogenic experiments on cooked bracken show that even processed bracken can induce intestinal cancer and bladder cancer, but the incubation period is long and the incidence rate is low. According to the results of the above scientific experiments, it shows that bracken contains carcinogens, and eating bracken increases the probability of cancer in people and animals. Therefore, people should not eat or eat less bracken in their diet. Pure natural bracken can cause cancer. Absent-minded Master of Chemistry, Tsinghua University, Ph.D. in Food Engineering, Purdue University, and author of Science Squirrel Club. In 2009, the popular science anthology "The Truth of Eating" was published. There is a plant called "foot moss" on the mountain in my hometown. My mother often said that there was not enough food in those years, and many people relied on it to tide over the difficulties. But by the time I was born, no one had eaten any more. By the time I was in high school, this plant was on fire again, and gradually its price exceeded that of most "domestic" vegetables. There are even special factories to process them, which are packed in very beautiful boxes and exported to other places. I also know the scientific name of this wild vegetable: bracken. Legend has it that it is not only "safe" and "pollution-free", but also rich in nutrition, and even has an "anti-cancer" effect. Pteridophyte is one of the most widely distributed plants in the world and is found in several continents. In many places, its buds are used as vegetables, and starch is extracted from its roots. More than a hundred years ago, people noticed that this plant could cause cow poisoning. Cattle that eat a lot of ferns-the European fern is its tender bud-will die within a few weeks at the earliest. People who don't eat so much gradually lose bone marrow function, leading to symptoms such as leukopenia, thrombocytopenia and acute bleeding. Sheep that eat ferns will gradually go blind. In 1960s, more studies found that ferns can also cause cancer. This discovery aroused great interest of scientists. Many studies have proved that bracken can really cause cancer in animals by tossing mice and other animals with bracken. If a synthetic substance or processed food has such a "bad record"-especially its carcinogenicity-it will definitely be criticized and "pulled out and shot for five minutes". But bracken is an "ancient", "pure natural" and "green food", and people can tolerate it to the point of "connivance". Even with the above-mentioned "criminal evidence", people only have a small range of "verbal warnings" about it. Brecon is still being chased. Can "pure natural" wild vegetables really cause cancer? This is too challenging for people's psychological limits. Pteridophyte is the first and perhaps the only edible plant that can cause cancer. Therefore, scientists are tirelessly trying to find out the cause of cancer. In the next twenty years, many people failed in their attempts. It seems that this carcinogen is very unstable and difficult to separate, and the confirmation of carcinogenicity is not so easy. In the early 1980s, a Japanese scientist successfully isolated something called ptaquiloside, which seems to be "protopterin" in Chinese translation. Since then, many people have done a lot of experiments on this thing and found that feeding it to animals will cause the symptoms mentioned above. Biochemical experiments show that it can also react with amino acids and destroy the genetic material DNA. In other words, it is more toxic than expected. Worst of all, it can be transferred from cow's food to milk, and it can also spread to water and soil. If cows eat fern, calves will have the symptoms of fern poisoning even if they only eat milk. This may also explain that people in areas where ferns grow vigorously have a much higher risk of cancer such as esophageal cancer even if they don't eat bracken. However, people's love for "wild vegetables" and "natural food" has brought protopterin to justice, but people are not far away from bracken. After all, sometimes the results of animal experiments can't appear in people, and the incidence of cancer itself is not so high-it has doubled or tripled, and people may not be able to understand it intuitively. Even if someone has cancer, it is hard to doubt that it is bracken, which has been eaten since humans didn't know what cancer was. On the other hand, the bracken people eat is just tender buds-is it as "spicy" as ginger? In other words, when people eat bracken, they should cook it on the spot. Will it destroy the toxin? Because proanthocyanidins are separated, the above two questions are well verified. Scientific experiments have found that protokeratin exists in all parts of ferns, and the content of bracken eaten by people is higher in the tender parts of ferns! However, it is a little comforting that the fresh bracken is bitter and astringent. Except for a few people who pursue "original taste" and "pure nature" infinitely, people usually treat fresh bracken with plant ash or alkaline water. This treatment will greatly reduce the content of the original bracken. Milk is generally sterilized at high temperature, which will greatly reduce the toxicity of protopterin. In 1970s, the relationship between eating bracken and esophageal cancer was investigated in the mountains of central Japan. The results showed that among the residents there, eating bracken increased the incidence of esophageal cancer in men by 2. 1 time and in women by 3.7 times. In North Wales, the incidence of gastric cancer has always been high. 1990, a case-control study also showed that eating bracken in childhood would increase the risk of gastric cancer in the future. Similar research has been done in other parts of the world and the results are basically the same. For most people, these findings only appear in academic journals. However, some people who promote "wild vegetables" are keen to cite "scientific research findings" to support "nature", "nutrition" and safety, but turn a blind eye to these studies. What's more, including some encyclopedia entries, it also claims that "scientific research in recent years shows that bracken also has a certain anti-cancer effect." One of the studies supporting this statement is that protopterin has a certain inhibitory effect on the growth of certain cancer cells-scientifically speaking, this result is far from saying that Pteridium aquilinum can resist cancer. Another survey supporting this function is that eating a small amount of bracken (once a month or longer) has a certain anti-cancer effect. The academic colleagues' evaluation of this research result is "surprising"-although it is statistically significant, this weak "cancer prevention effect" may be a "digital illusion" because of the small sample size.