(Photo : WHO)

Planning to start Intermittent fasting? You should reconsider your decision as it can place you at the risk of cancer, new research warns.

The study published in Nature found both positive and negative effects of fasting. Experiments conducted on mice showed that while fasting helped stem cells in the intestine to regenerate and heal injuries, it also increased the risk of developing cancer.

For the study, a team of researchers from theMassachusetts Institute of Technology, placed mice under three different fasting plans. The first group of mice fasted for 24 hours, the second group fasted for 24 hours and ate everything during the 24 hour 'refeeding period' and the last non-fasting group ate everything during the experiment.

Scientists identified the pathway that helped improve regenerative abilities of intestinal stem cells. Though regeneration helped intestine to recover from injuries and inflammation, researchers noticed that the process of regenerationalso led to cancerous mutations and development of intestinal tumors.

"Having more stem cell activity is good for regeneration, but too much of a good thing over time can have less favorable consequences," Omer Yilmaz, an MIT associate professor of biology, a member of MIT's Koch Institute for Integrative Cancer Researchand the senior author of the new study, said in a statement.

"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," he continued, adding that, further studies in humans are required to confirm the findings.

Previous studies conducted by the team have shown role of fasting in improving stem cells capacity to regenerate.  In the new study, researchers foundthat stem cell's ability toproliferatewas highest at the end of the 24-hour refeeding period and proliferation was higher in the mice that underwent fasting and refeeding than the non-fasting rodents.

Using lipids and fatty acids as energy source, cells survive the fasting period and during the refeeding period, stem and progenitor cells activate programs which help them build cellular mass and repopulate intestinal lining,one of the lead authors of the study, Shinya Imada explained.

These cells later activated a cellular signaling pathway involved in cell growth and metabolism called mTOR. mTOR plays a huge role in regulating translation of messenger RNA into protein and mTOR activation leads to the production of more protein, facilitating proliferation of stem cells. Activation of mTORalso helped produce large number of polyamines or the small molecules which support cells to grow and divide.

Whenstem cells reached the regenerative state, they were found to be more cancerous. Also, as stem cells in the intestine are one of the most frequently divided cells in the body, it can increase the risk of cancer.

Researchers said that turning on a cancer-causing gene during the refeeding stage placed the mice at higher risk of developing precancerous polyps than turning on while in fasting period.

The mutations linked to cancer produced during the refeeding state produced more polyps in mice than mutations occurred during non-fasting.

"I want to emphasize that this was all done in mice, using very well-defined cancer mutations. In humans it's going to be a much more complex state," Yilmaz said. "But it does lead us to the following notion: Fasting is very healthy, but if you're unlucky and you're refeeding after a fasting, and you get exposed to a mutagen, like a charred steak or something, you might actually be increasing your chances of developing a lesion that can go on to give rise to cancer."

The findings bring hope to people undergoingradiation treatment that damages intestinal lining or people who are affected with intestinal injury.

"Their work lays a foundation for testing polyamines as compounds that may augment intestinal repair after injuries, and it suggests that careful consideration is needed when planning diet-based strategies for regeneration to avoid increasing cancer risk."Ophir Klein, a professor of medicine at the University of California at San Francisco and Cedars-Sinai Medical Center, who was not involved in the study, said.

The findings come at a time when intermittent fasting, a concept based on the 'time' when one eats meals has become very popular recently. Contrary to the new research, previous research has shown its power in managing weight and protecting against certain diseases. According to health experts at Mayo Clinic, intermittent fasting can help reduce inflammation and conditions related to inflammation including asthma, stroke, Arthritis, Alzheimer's disease and multiple sclerosis.