The Effects of Intermittent Fasting on Stem Cells and Increased Cancer Risks
Disclaimer: I do not advocate for the benefits or harm of fasting. The purpose of this article is to share an interesting observation made by researchers in their field. There are a number of practices that have even found reflection in religious doctrines and are known as fasts, that fasting correlates with some benefit to the body and health in general. However, a new study on micepoints out the risks of consequences of intermittent fasting.
The body is wonderful because it is adapted to survive in different conditions, so our homeostasis is quite stable. But systemic actions, starting from lifestyle, adequate sleep, training and nutrition, ending with the systematic use of caffeine, sports nutrition and dietary supplements, can make adjustments to our appearance and well-being in general.
How does fasting cause cancer?
MIT Research revealed the exact mechanismwhereby fasting causes the regeneration of intestinal stem cells, and this is one of the benefits of the practice. However, if you exit the fasting phase too quickly, it triggers the mechanism of cancer cell formation.
Periods of fasting
Fasting, whether for a few days a week or a few hours a day, has become a popular approach used by thousands of people to manage their weight, relieve gastrointestinal stress, or potentially improve overall health in the case of overweight people. For example, a study conducted in early 2024 found that fasting for 24 hours twice a week boosted the ability of natural killer cells to fight cancer cells.
Omer Yilmaz, an associate professor of biology and a member of the MIT Koch Institute for Integrative Cancer Research, has studied the effects of fasting in rodents for years. In 2018, he and his team found that 24-hour fasting speeds up the regeneration of intestinal stem cells, a process that naturally slows with age.
Now Yilmaz has led a study that has identified the ways in which fasting affects the body. And it has uncovered a potentially dangerous complication during the recovery phase.
The study's authors found that it was not so much the fasting itself that caused stem cell regeneration, but rather the “refeeding” period that occurs when a person begins to eat properly again.
In general, our gastrointestinal tract is quite complex and affects both the body's metabolism and mental states. to the point of depression.
The positive side of the feeding period
To reach this conclusion, the researchers divided the mice into three groups:
The first group fasted for 24 hours and gradually came out of the fast.
The second group fasted for 24 hours and then ate whatever they wanted during a subsequent 24-hour feeding period.
A control group that simply ate as usual during the study period.
The scientists found that the highest rate of intestinal stem cell regeneration occurred at the end of the 24-hour period of refeeding, that is, in the second group.
We think of fasting and refeeding as two different states. In the fasted state, the ability of cells to use lipids and fatty acids as an energy source allows them to survive when nutrients are scarce. And then it’s the refeeding state after fasting that really stimulates regeneration. When nutrients become available, these stem cells and progenitor cells activate programs that allow them to build up cell mass and repopulate the intestinal lining.
Shinya Imada, a postdoctoral fellow at MIT, is one of the lead authors of the study.
Incorrect type of regeneration
But there was a catch. The researchers found that during this extensive regeneration period, the intestinal stem cells were more likely to become cancerous. They reached this conclusion by testing a 24-hour fast/refeed regimen in mice that had a cancer-causing gene turned on. The cancer mutations they observed during the regeneration phase were also more likely to lead to polyps than in cancer-prone mice that weren’t fasting.
Although intestinal stem cells are always more prone to cancer-causing mutations because of their high rate of division, the researchers say the findings may be cause for concern. Importantly, rodent findings do not always translate to humans.
I want to emphasize that this was all done in mice using very well-defined cancer mutations. In humans, it would be a much more complex condition. But that brings us to the next point: fasting is very beneficial, but if you're unlucky and you refeed after fasting, and you're exposed to a mutagen, like a charred steak or something like that, you can actually increase your chances of developing factors that can lead to cancer.
Shinya Imada, a postdoctoral fellow at MIT, is one of the lead authors of the study.
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