Intermittent fasting may heal cells but leads to higher cancer risk

Intermittent fasting can boost the regenerative abilities of intestinal stem cells, a new study on mice showed, but it also had some downsides.

Intermittent fasting has become one of the most popular diets, with research linking it to several health benefits. 
However, researchers are still investigating its effects on metabolism.
In a study on mice, a team from the Massachusetts Institute of Technology (MIT) in the US looked at how fasting can help intestinal stem cells regenerate. 
These cells are the source of new intestinal cells and their regeneration can help the intestine.
They observed three groups of mice: the first group fasted for 24 hours, the second group fasted for 24 hours and then had unrestricted eating during the next 24 hours, and the third control group ate freely throughout the entire experiment.
Researchers identified a specific pathway responsible for improved regeneration which becomes active when the mice resume eating after a period of fasting, according to their findings published in the journal Nature.
“We think that fasting and refeeding represent two distinct states,” Shinya Imada, a postdoctoral researcher at MIT and one of the study’s lead authors, said in a statement.
“In the fasted state, the ability of cells to use lipids and fatty acids as an energy source enables them to survive when nutrients are low. And then it’s the postfast refeeding state that really drives the regeneration. When nutrients become available, these stem cells and progenitor cells activate programmes that enable them to build cellular mass and repopulate the intestinal lining,” he added.
However, there’s a caveat: if cancerous mutations occur during this regenerative phase, the mice are at a higher risk of developing early-stage intestinal tumours.
“Having more stem cell activity is good for regeneration, but too much of a good thing over time can have less favourable consequences,” said Omer Yilmaz, an associate professor of biology at MIT and the senior author of the new study. 
Intestinal stem cells help to renew the lining of the intestine, which is replaced entirely every five to ten days.
This rapid division makes them more likely to develop precancerous changes than other cell types in the intestine.
Researchers also discovered that mutations that developed during the refeeding phase were more likely to lead to polyp formation compared to those that occurred in mice that didn’t fast.
Researchers highlighted that the study was conducted in mice with specific cancer mutations and that the more intricate human context may yield different results.
“We still have a lot to learn, but it is interesting that being in either the state of fasting or refeeding when exposure to mutagen occurs can have a profound impact on the likelihood of developing a cancer in these well-defined mouse models,” Yilmaz said.