Here is a brief introduction to the study on “How bowel cancer is eaten” in Nature magazine. High protein diet is an important cause of colorectal cancer Diet, especially high-fat and high-protein diet, is an important cause of colorectal cancer. In China, the incidence of colon cancer is increasing year by year, and the incidence rate has risen to the second highest in large and medium-sized cities, and the age of patients also tends to be younger, with the incidence rate within 35 years old increasing. The common high-protein and high-fat diet in large and medium-sized cities also confirms the relationship between high-fat and high-protein diet and the occurrence of colon cancer. Back to the point!!! Why does a high-fat and high-protein diet lead to the occurrence of colon cancer? Let’s first understand a term called “intestinal stem cells”. Intestinal Stem Cells Stem cells are under-differentiated, immature cells that have the potential to regenerate various tissues, organs and the human body, and are called “universal cells” in the medical field. It is like a “boot camp”, where recruits are trained to become different types of soldiers, such as communication soldiers, tank soldiers, artillery soldiers and scout soldiers. The same is true for “intestinal stem cells”, which are hidden in a place called “basal crypt” under the intestinal mucosa and normally migrate towards the intestinal mucosa. In the process of migration, they differentiate to form different intestinal mucosal cells as needed to replace the intestinal mucosal cells that die due to normal metabolism. But under abnormal conditions, it is different. A new study from the Massachusetts Institute of Technology found that mice fed a high-fat diet experienced a dramatic increase in the number of intestinal stem cells, as well as the creation of pools of other cells – which, like stem cells, can proliferate and differentiate into other cell types indefinitely on their own. These “stem cell-like” cells are the big problem, stimulated by a high-fat diet, and acquire stem cell properties, that is, the proliferation of these pseudostem cells leads to differentiation into non-functional cells that form tumors in the intestinal wall. Pseudostem cells appear in large numbers and form tumors Another study conducted in Germany found that a high-fat, high-protein diet leads to changes in intestinal flora, which increases the risk of developing colorectal cancer. Intestinal flora There are three types of bacteria in the intestine, beneficial bacteria, harmful bacteria and neutral bacteria, among which beneficial bacteria, also known as probiotics, are mainly various bifidobacteria and lactobacilli, which are indispensable elements for human health and can synthesize various vitamins, participate in the digestion of food, promote intestinal peristalsis, inhibit the growth of pathogenic flora and decompose harmful and toxic substances. Neutral bacteria, i.e. bacteria with dual roles, such as E. coli and enterococci, are beneficial to health under normal conditions, but once they proliferate out of control or are transferred from the intestine to other parts of the body, they may cause many problems. Once the number of harmful bacteria grows out of control in large numbers, it can cause many diseases and produce harmful substances such as carcinogens, which can lead to the occurrence of intestinal cancer. The health of human body is closely related to the structure of flora in the intestine. During the long-term evolution of intestinal flora, through individual adaptation and natural selection, different species of flora, between flora and host, between flora, human body and environment, are always in a dynamic balance, forming an interdependent and mutually restrained system, therefore, under normal circumstances, the flora structure of human body is relatively stable. However, a high-fat, high-protein diet can lead to changes in the structure of the flora, as suggested by the process of this German study: the researchers fed two groups of mice susceptible to colorectal cancer with a high-fat and low-fat diet, collected the mice’s feces, and examined the changes in the flora of the two groups. The incidence of colorectal cancer was significantly higher in the high-fat diet group. The incidence of colorectal cancer was also significantly increased in the low-fat diet group, after purifying and culturing the fecal flora from the high-fat diet group into the intestine of the low-fat diet group. Such a cross-validation experiment effectively verified that changes in the types and ratios of intestinal flora can lead to changes in the incidence of colorectal cancer. Therefore, these two studies reveal the effect of high-fat and high-protein diet on the development of colorectal cancer from two perspectives, one is the proliferation of “stem cell-like” cells in the intestinal wall as an internal response, and the other is the disorganized intestinal flora as an external response. One is the large number of proliferating “stem cell-like” cells in the intestinal wall as an internal response, and the other is the disorganized intestinal bacteria in the intestinal lumen as an external response, which leads to the development of intestinal cancer. Therefore, we should pay attention to the fact that both fat and protein are nutrients needed by the human body, but too much is not enough, so we should reasonably supplement fat and protein in our daily diet.