The effects of fasting on our bodies may be more complicated than we thought. A new study in mice suggests that fasting may speed up the healing of intestinal stem cells, but it may also make them more susceptible to cancer. The findings could help optimize popular diets like intermittent fasting, the researchers say.
Scientists at MIT led the new study. Published Wednesday Journal NaturePrevious research has shown that fasting enhances the regenerative capacity of intestinal stem cells, but this time the focus has shifted to how this process works.
The researchers studied intestinal stem cells in three groups of mice: a control group that ate normally, mice that fasted for 24 hours, and mice that fasted and then ate as much as they wanted for the next 24 hours. They found that fasting suppressed intestinal stem cell regeneration, but that regeneration accelerated when the mice began eating again.
“The main finding of this study is that refeeding after fasting is a different state to fasting itself. Refeeding after fasting enhances the capacity of intestinal stem cells, for example to repair the intestine after injury,” says researcher Omer Yilmaz. Shinya Imada and Saleh Kawared told Gizmodo in an email.
This boost in regeneration may help intestinal cells heal faster, but the researchers found that it could come at a cost if things go wrong: When the researchers induced cancer-associated mutations in these stem cells during the refeeding phase, the cells were significantly more likely to trigger the formation of precancerous polyps than during the fasting phase.
The authors are quick to point out that the real-world effects of fasting in humans are much more complicated than what’s seen in lab mice, and more research is needed to know whether we see the same changes — good or bad — in human intestinal stem cells before and after fasting.
“Biological pathways are highly complex and interconnected. The main message from this study is that careful studies are needed to test the effects of dietary interventions in humans,” the researchers said.
But the lessons learned here are sure to help us better understand fasting. The researchers found that fasting mice produced higher amounts of polyamines, organic compounds that help cells grow, divide, and turn into other cells. So in future studies, the researchers plan to test whether fasting can be easily mimicked using polyamine supplements. And they hope that these studies will help us get the most out of fasting.
“Although intermittent fasting is a very popular dietary approach used by millions of people worldwide and has proven to have significant benefits for many diseases, careful analysis of the contribution of each fasting phase (fasting and refeeding after fasting) may provide a better understanding of how to design dietary interventions to maximize regeneration while avoiding increased risks of other diseases such as cancer,” the researchers said.
