Recently, there was a news piece that went viral on social media. The message claims that if you "sleep with wet hair," you're allowing a cancer-causing microorganism to multiply on your scalp, which in turn can spike your cancer risk.
What's going on here?Can sleeping with wet hair really cause cancer?The truth is actually far from the conclusion of this news......
Weibo screenshot first talks about the conclusion,Malassezia is a normal parasite on the surface of the human body, which likes a humid environment, but wet hair may not produce a large number of Malassezia. In addition, the study did not mention that Malassezia in pancreatic cancer comes from the scalp, and Malassezia is a conditionally pathogenic bacteria that normally coexists peacefully with people. There are also no studies that prove that the tumor growth is related to the fungus on the scalp. This myth simply uses the common factor of "dampness" to link wet hair to cancer. Sleeping with wet hair causes cancer
How did this rumor come about?
If you open this article, you can find that the author took great pains to come up with a 2019 issue of the journal Nature** as a basis. There is nothing wrong with this article itself: the authors found that the cancerous process of some tumors is often accompanied by microbial dysbiosis.
There's nothing wrong with the study itselfThrough their research, they found that pancreatic ductal adenocarcinoma is closely linked to fungi – tumors in patients with this cancer have about 3,000-fold increased levels of fungi compared to normal pancreatic tissue!Analytically, these fungi are clearly rich in members of the genus Malassezia.
To understand the causal relationship between these fungi and the onset of cancer, the researchers further explored the mechanisms behind them. They found that if these fungi were killed, they could play a protective role in a cancer model in mice. Similarly, transplanting these fungi into a mouse model of disease can accelerate the process of cancer. Based on these findings, the researchers saidThese pathogenic fungi can promote the development of pancreatic ductal adenocarcinoma through a molecular mechanism.
The fact that this study was published in the journal Nature certainly shows that it is rigorous and reliable. ButWhat does this have to do with "wet hair"?
This news does not give clear evidence, only that Malassezia likes a humid environment, and freshly washed hair, of course, is also damp. That is, just by using the common factor of "dampness", the author of this news used his imagination to associate wet hair with cancer.
Why is this news unreliable?
If we read the article "Nature" carefully, we will find that the way Malassezia promotes cancer is really difficult to hook up with hair.
Stock Copyright**, using the authors of a potentially copyright dispute** did an experiment in labeling fungi with fluorescent proteins so that they could shine visibly under a microscope.
In this way, they found that the fungus can "run" from the gut to the pancreatic location, which has a promoting effect on the tumor. As a member of the digestive tract, this movement of the fungus can be said to be a visit between neighbors. And to run from damp hair to the pancreas, it takes a lot of work.
In addition, there is no clear supporting evidence that dampness can breed Malassezia. If there's anything that can contribute to the growth of this fungus, fat is an essential nutrient, which explains why this bacterium often causes infections — they like the oil they secrete.
Because of this, regardless of whether the hair is damp or not, the number of Malassezia bacteria in an average person's head can be as high as tens of millions. If the logic in this news is followed, everyone's risk of cancer is probably soaring all the time.
How to properly understand a cancer study?
The reason why this news, which is full of doubts at first glance, can still explode may also show that ordinary people do not understand cancer research, and often believe those exaggerated conclusions based on their own words.
When it comes to how to properly understand cancer research, it may be divided into several points, one is the research on the carcinogenes of a certain substance, which also includes the Malassezia mentioned in this article. Generally speaking, to prove that a substance causes cancer, it still needs relatively sufficient evidenceIt is necessary not only to find the mechanism of carcinogenesis in animal studies, but also to confirm the same carcinogenic mechanism in humans.
Going back to this article in Nature, most of the research work is actually carried out in mouse disease models, and in order to simulate human cancer, these mice themselves have undergone many modifications and have certain particularities. The results observed in these mice cannot be simply extrapolated to humans. As for whether human beings will be affected, more, longer, and more in-depth research is needed.
Another type of cancer research may be related to cancer. For example, when can cancer disappear, or when scientists have created drugs that can completely ** cancer. If we break down these studies, we find that most of them are also based on animal experiments, even cell studies.
There are a few words in the pharmaceutical industry, and one sentence is true"If human physiology were the same as mice, then cancer would have been ** long ago." This statement illustrates that positive outcomes in animal research do not always extend to humans.
As for cell research, it's even further away. A joking quote goes something like this: "If someone says that a certain drug kills cancer cells, remember, boiling water will do." ”Drugs that kill cancer cells don't necessarily work in the human body. It may be easily degraded by the human body, or it may not be able to touch tumors buried deep in tissues, or it may be too toxic for human use, etc.
The reason why these rumors appear is also largely because some ** reports will use exaggerated language to attract attention. In a sense, it's more appropriate to watch these stories as a pleasure. After all, there are only a dozen or twenty new cancer drugs born every year in the world, which shows how difficult it is to understand cancer.
If there is a "blockbuster" cancer news every three or five days, it is most likely not as heavy as it claims.
Summary
Although this myth is substantiated that wet hair will cause Malassezia to multiply, and it has been used in Nature to prove that Malassezia can promote the development of cancer, the premise that "wet hair will produce Malassezia in large quantities" may not be true.
On the contrary, no matter whether the hair is dry or wet, there are quite a few of these fungi on the head of every normal person. What's more, a study in the journal Nature found that if pancreatic cancer is to be promoted, microorganisms must move from the gut to the pancreatic site. These two parts are also very different from the hair.
Looking to the future,If you come across news such as cancer with simple lifestyle habits, we can first determine whether the content is justified or just causing anxiety. If the news does not talk about the animal model of the study, does not talk about the sample size, does not talk about the limitations of the study itself, does not talk about the difference between causality and correlation, and does not talk about the fact that the conclusion cannot be extrapolated indefinitely, then we should be careful when reading this kind of news to avoid being deceived.
*: Popular Science China.
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