A team of German researchers has shown how the so-called "Western diet", which often contains large amounts of fatty foods, can contribute to the development of one of the most common, and even deadly, types of cancer in adults under the age of fifty.
The study was carried out by a group of researchers from German universities, namely the Technical University of Munich, the Technical University of Aachen, and the German Institute for Human Nutrition in Potsdam-Rebrücke.
The joint study revealed that unhealthy diets, such as fast food, help maintain the presence of certain types of gut bacteria that produce secondary bile acid, which in turn promotes the growth of tumors.
In an interview with DW, Annika Oswald, a researcher at the German Institute and participant in the study, said, "What distinguishes the work we have done is to prove the causal relationship. Before the study, we only knew that there was some kind of association between a certain type of secondary bile acids and colorectal cancer."
Doctors say that the fats in food stimulate the liver to produce primary bile acids.
The function of these acids is that our bodies need them to break down fats and absorb them. While most of these acids are reabsorbed and returned to the liver, a small percentage of them reach the colon, where certain types of bacteria convert them into secondary bile acids.
Among these acids is an acid known as deoxycholic acid. Doctors say that the more foods rich in fat a person eats, the higher the concentration of deoxycholic acid in the colon.
"This is where the problem starts"
Oswald and the researchers who participated in the study tested this mechanism on laboratory mice. In that, she said that the experiment on mice “was a fundamental focus of our work to prove the existence of a causal relationship.”
In order to prove the relationship directly, the researchers conducted the experiment on mice by dividing them into two groups. The first group had bacteria producing deoxycholic acid implanted in their intestines, while another group was left without these bacteria.
When the development of colorectal cancer was stimulated in the bodies of mice, whether those that had this acid implanted in their bodies or not.
The results of the experiment revealed that mice whose intestines contained this acid developed larger and more growing tumors than their counterparts.
The matter did not stop there, as researchers noticed that the rate of cell division increased significantly in mice whose bodies contained this acid. In light of these results, the researchers concluded that the matter may increase the possibility of genetic errors and mutations that may accumulate over time and turn into cancer.
After the success of the laboratory experiments, the researchers moved on to studying human samples, where they analyzed stool samples from more than a thousand people, some of whom had colorectal cancer while others were healthy.
The results revealed that genes associated with bacteria that produce this acid were more prevalent among those infected with the disease, which reinforces the hypothesis that these bacteria may play an important role in the development of cancerous diseases.
"Gut health"
In this context, researcher Annika Oswald, who participated in the study, said that the great importance of the study lies in the fact that it not only showed the existence of a relationship between acid and colon cancer, but also provided strong evidence of the existence of a direct causal relationship between them.
The researchers believe that the results of the study may open the door to new therapeutic strategies that target intestinal bacteria or reduce the production of this harmful acid, instead of focusing on the tumor only.
"Our results show the extent to which a high-fat diet and associated changes in the gut microbiome can have an impact on human gut health," said microbiologist Søren Ökverk, one of the study's co-authors.
Prevention...the most powerful weapon
Despite scientific progress, researchers confirm that the best way to confront colorectal cancer is prevention before the disease appears.
Researchers point out that there are simple steps that may make a big difference in protecting intestinal health and reducing the risk of cancer. The researchers said that among these steps are relying on a balanced diet, reducing the consumption of meat and fatty foods, increasing the consumption of vegetables and fiber, and avoiding smoking.
