Fasting promotes cell regeneration, but also leaves cells vulnerable to cancerous mutations.
Eating is one of life’s few constants: If you’re not eating right now, you’ll certainly be eating something within a few hours. But when and how often we should eat is still not fully understood.
Scientists have spent decades trying to understand how periods of eating and fasting affect the body. While fasting interventions have been linked to extended lifespan and tissue regeneration, scientists are still piecing together the mechanisms involved.
It turns out patterns of fasting and eating may affect cell regeneration, which is connected to cancerous mutations.
A new study in mice from Massachusetts Institute of Technology, published today in the journal Nature, identified the pathway that switches on this cell regeneration — and found a downside to it. While fasting boosts regeneration of intestinal stem cells, mutations that occurred during the eating period after fasting could produce early-stage intestinal tumors. This finding is important because it demonstrates a new way in which fasting can be a double-edged sword.
The MIT team looked at three groups of mice. One experimental group fasted for 24 hours, another experimental group fasted for 24 hours and then ate whatever they wanted in the following 24 hours, and the control group ate as they pleased the entire time. During this period, the researchers analyzed the mice’s intestinal cells. Intestinal cells are some of the body’s most actively dividing cells, completely remaking the intestinal lining every 5 to 10 days. However, rapid cell division also puts cells at higher risk for cancerous mutations. These stem cells, then, are the most common source of precancerous cells in the intestine.
When they analyzed the mice’s intestinal stem cells, the researchers found that regeneration was suppressed during fasting. However, it surged during the refeeding period for the mice who first fasted and then ate during the following 24 hours. These cells proliferated even more than those of mice who hadn’t fasted. But there’s a drawback to this rapid regeneration. When cancerous mutations cropped up during the high proliferation period — which the team induced with a cancer-causing gene — the mice were more prone to developing early-stage 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,” senior author Ömer Yilmaz, an MIT associate professor of biology, said in a press release.
While fasting can be healthy, it also creates more opportunities for cell vulnerability to cancer-causing mutations — so be mindful of what you eat following a fast.