Wechat moments: are mushrooms rich in heavy metals?

Rumor: you can't eat more mushrooms. You can eat up to 200g per month. Although mushrooms are good, they have a very important feature, that is, they have a strong ability to enrich heavy metals, which can reach more than 100 times at most. Almost all heavy metals, such as lead, mercury, nickel and mushrooms, are enriched. However, our human bodies do not have the mechanism to excrete heavy metals. Over time, these heavy metals will accumulate in the renal tubules, and even cause renal tubular necrosis in severe cases.

Truth: mushroom is our common name for edible macrofungi, including mushrooms, shiitake mushrooms, Flammulina velutipes, Coprinus comatus and many other varieties. Mushrooms do have a higher ability to accumulate heavy metals than green plants. Foreign researchers have done some investigations on the content of heavy metals in wild mushrooms. In recent years, many scientific research colleges and universities in China have investigated the artificially cultivated edible mushrooms. For example, in 2007, a study investigated the content of heavy metals in edible fungi in Beibei, Chongqing. This area is not only an important industrial base, but also a production base of edible fungi. The researchers analyzed the heavy metals such as lead, cadmium, mercury and arsenic in Pleurotus ostreatus, Coprinus comatus, Flammulina velutipes, Flammulina velutipes and volvariella volvacea, and found that volvariella volvacea had the strongest ability to accumulate heavy metals. All straw mushroom samples were found to exceed the standard of mercury, 1/3 of straw mushroom samples exceeded the standard of lead, 14% of the samples of Coprinus comatus exceeded the standard of mercury, 4% of the samples of Lentinus edodes exceeded the standard of lead, and 29% of the samples of Mushroom exceeded the standard of mercury and lead. [1]

The phenomenon of excessive heavy metals in mushroom food is not limited to Chongqing. Golden mushrooms from the Qinghai-Tibet Plateau are also found to contain excessive cadmium and mercury, and the contents of lead and arsenic are much higher than those of Lentinus edodes and Agaricus bisporus. Similar results have been obtained in the study of another large fungus, Ganoderma lucidum. Although it is considered by some to be a magic drug, some researchers have found that some samples are rich in lead. Researchers in Taiwan also investigated Brazilian mushrooms (Agaricus blazei or Agaricus blazei Murrill) and found that nearly half of the samples had excessive cadmium levels. However, in 2009, researchers from Zhejiang Forestry University and other units conducted spot checks on mushroom samples on the Zhejiang market and did not find the phenomenon of excessive heavy metals, but compared with ordinary vegetables, their content was indeed on the high side and exceeded the heavy metal limit standard for vegetables. [2]

However, heavy metal is not a necessary element in mushrooms, and it is not good for the growth of mushrooms. Then why are the heavy metals in mushrooms so high? Where did these heavy metals come from? In fact, the reason for the high content of heavy metals is that mushrooms produce some proteins that can complex with heavy metals and detoxify them by complexing with heavy metals to form non-toxic complexes, so that mushrooms are not afraid of heavy metals; and in the environment, especially in the polluted environment, there are often a large number of heavy metals, so mushrooms "accidentally" eat these heavy metals into their bellies, and accumulate more and more.

The heavy metals in mushrooms, unlike the toxins synthesized by some poisonous mushrooms themselves, come from the environment and are not what they want. If the culture medium is not contaminated, our favorite mushrooms are still good food. Some farmers do not understand the environment and use silt to grow mushrooms. Although there are many nutrient elements in the sludge, if the content of heavy metals in natural water bodies such as rivers is too high due to sewage, using it to plant mushrooms may cause heavy metals in mushrooms to seriously exceed the standard.

So, will these heavy metals have an impact on the human body? Come to think of it, mushrooms deal with absorbed heavy metals by synthesizing complex proteins, and it is a bit belittling to say that humans have "no mechanism to expel heavy metals." In fact, metallothionein with similar function also exists in the human body, and if the amount of heavy metals in the body increases, it will induce the production of more metallothionein and improve the detoxification ability. In addition, glutathione in the liver can also bind to heavy metal ions and further excreted through the digestive tract, playing a detoxifying effect. For some specific heavy metals, there will be specific ways of metabolism to achieve detoxification and excretion. For example, arsenic can be converted into less toxic monomethyl arsenic and dimethyl arsenic in the human body and is more likely to be excreted from the body. Organs such as kidney, liver and even lungs have the function of excreting heavy metals. Generally speaking, our body's own ability to metabolize heavy metals can protect us from their toxicity unless there is a large or long-term over-dose intake of toxic heavy metals.

According to the survey results of some scientific research institutions that do not have the function of food supervision, there is indeed a phenomenon of excessive heavy metals in mushrooms in China's market, so what should we do if we like to eat mushrooms? Generally speaking, the content of heavy metals in wild mushrooms is higher than that in artificial cultivation, and mushrooms that need to be cultivated in soil, such as Agaricus bisporus, Coprinus comatus, Pleurotus ostreatus, etc., are easily polluted by heavy metals in the soil. Relatively speaking, the content of heavy metals in mushrooms cultivated with straw is small.

As ordinary people, it is difficult for us to accurately judge the pollution of heavy metals in food. Hope that our environmental monitoring department, food safety management department, can be more effective, for ourselves, but also for our future generations, leaving a more sense of security agricultural economy.

Conclusion: it is partially confirmed. Edible macrofungi such as mushrooms may indeed have excessive heavy metals, which is related to whether the culture medium contains a large amount of heavy metals. The human body has the ability to metabolize heavy metals, but if the intake of toxic heavy metals exceeds the dose for a long time, it may bring harm.

Reference:

Li Yong, Zhang Xiaoyan, Yuan Lin, investigation and Analysis of heavy Metal content of Edible Fungi in Beibei area of Chongqing, Journal of Chongqing normal University (Natural Science Edition), No. 1-5, 2007

Wei Hailong, Chai Zhenlin, Wu Xueqian, Lu Aihua, Shang Suwei, Zhu Jieli, background value and quality safety evaluation of heavy metals in mushrooms in Zhejiang Province. Zhejiang Forestry Science and Technology, Volume 29, No. 3, 2009 39-42.

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A netizen asked this newspaper yesterday that she saw an article on Wechat saying that you should not eat more than 200g of mushrooms per month, otherwise heavy metals would exceed the limit. To this end, the reporter interviewed Xie precious, an expert appointed by the technical system of the national edible fungus industry and a professor of Fujian Agriculture and Forestry University. He told reporters that this statement is a rumor, as long as there are no artificial factors, edible fungus products are very safe.

Netizens dare not eat mushrooms after reading the Wechat article.

The netizen surnamed Ye said that her family loves to eat mushrooms, shiitake mushrooms, Flammulina velutipes, tea tree mushrooms, fungus and so on, and they must buy these mushrooms when they go to the vegetable market or supermarket. It has always been believed that edible mushrooms are rich in amino acids, vitamins and minerals. However, recently, she saw an article on Wechat moments, saying that you can't eat more mushrooms, only 200g at most per month, because mushrooms have a strong ability to enrich heavy metals. Over time, these heavy metals will accumulate in the renal tubules and, in severe cases, cause renal tubular necrosis.

She said that after reading this article, she dared not eat it and told her mother not to buy it, but her family loved it. What should she do?

The reporter found that the article circulated on the Internet was a doctor who claimed to have studied pathology at the University of Zurich Hospital. He came into contact with a doctor named Guhl, who studies fungi in the department of biochemistry. He revealed that mushrooms are not allowed to eat more. They can eat up to 200g a month. Because although mushrooms are good, they have a strong ability to enrich heavy metals, up to 100 times. The author of the article also said, "I read a report in the New Zurich newspaper that in the areas contaminated by the Chernobyl nuclear accident in Ukraine and Germany, the prescription given by experts is to plant mushrooms vigorously to enrich the heavy metals and harmful metals in these radiation-contaminated areas, so as to restore these areas to pre-pollution levels as soon as possible." A sampling conducted by the Ministry of Agriculture: the content of heavy metals in edible fungi is far lower than the national standard.

"there is no basis for nonsense." In view of this, yesterday, the reporter interviewed Xie precious, an expert hired by the technical system of the national edible fungus industry and a professor of Fujian Agriculture and Forestry University. When the reporter told Professor Xie the content of this Wechat article, he flatly denied: "this is a rumor." Some time ago, a friend asked me if mushrooms enrich heavy metals. I am very surprised because the concept of a healthy diet that the Food and Agriculture Organization of the United Nations and the World Health Organization have been promoting includes eating mushrooms. Edible fungi have always been regarded as healthy food. "

Professor Xie said that with regard to the safety of edible fungi, the Ministry of Agriculture randomly sampled 2000 fresh mushroom products from all over the country in 2010 to detect agricultural residues and heavy metals. As far as the content of heavy metal lead is concerned, the average content of fresh edible fungi per kilogram is 0.065 mg, which is much lower than the national standard (1 mg). It is also below the International Food and Agriculture Organization / Health Organization (FAO/ WHO) standard (weekly intake of no more than 0.025 mg per kilogram of body weight).

"according to FAO/WHO standards, a 60-kilogram adult would have to eat more than 92 kilograms of fresh edible fungi a month to have excessive lead intake." Xie precious said that it is impossible for the public to eat edible mushrooms as rice, so there is no such thing as excessive heavy metals unless they are artificially added.

The production of edible fungi under simulated pollution is still very safe.

He said that his team had just completed the major project "Research on the breeding of New varieties of Edible Fungi and safe production Technology" of the Provincial Science and Technology Department the year before last, which gathered more than 30 experts from the whole province. the pesticide residues and heavy metal contents of ten major edible fungi were studied for three years. They tested and analyzed 10 kinds of main edible mushroom products on the market, including Lentinus edodes, mushrooms, Flammulina velutipes, tea tree mushrooms, apricot abalone mushrooms, Xiuzhen mushrooms, chicken leg mushrooms, hericium Erinaceus, Agaricus blazei Murrill and Auricularia auricula, which not only meet the requirements of national pollution-free food, but also meet the "positive list" of Japan and the food standards of the European Union.

This research project also simulates the production of edible mushroom cultivation raw materials under different degrees of pollution, detects the content of pesticides and heavy metals, and establishes the regression equation of pesticide and heavy metal content between cultivated raw materials and mushroom body. in order to predict the safety of edible mushroom products. "the results show that although the sources of raw materials are different, as long as there are no artificial factors, edible mushroom products are very safe, and no problems mentioned in this article have been found." Professor Xie said.

Source of Wechat article: gossip of an obstetrician and gynecologist

Xie precious said that in the spirit of curiosity, he also went to the Internet to track the context of this article. This article was published as early as 2008 by an obstetrician and gynecologist named "salty rice in white clothes". In July 2010, "salty rice in white" published another article on Sina blog. This blog post was led by "salty rice in white" when it claimed to invite Lao Gu, a doctoral student from the University of Zurich, to dinner. it was not quoted from the research report, nor from the survey results of authoritative testing institutions, but more ridicule and subjective ideas.