Max Kozlov in Nature: Breaking a fast carries more health benefits than the fasting itself, a study in mice shows1. After mice had abstained from food, stem cells surged to repair damage in their intestines — but only when the mice were tucking into their chow again, the study found. But this activation of stem cells came at a price: mice were more likely to develop precancerous polyps in their intestines if they incurred a cancer-causing genetic change during the post-fasting period than if they hadn’t fasted at all. These results, published in Nature on 21 August, show that “regeneration isn’t cost-free”, says Emmanuelle Passegué, a stem-cell biologist at Columbia University Irving Medical Center in New York City, who wasn’t involved in the study. “There is a dark side that is important to consider.”
Fast way to health
Researchers have been investigating the potential health benefits of fasting for decades, and there is evidence that the practice can help to delay certain diseases and lengthen lifespan in rodents. But the underlying biological mechanisms behind these benefits have been a mystery. In 2018, Ömer Yilmaz, a stem-cell biologist at the Massachusetts Institute of Technology in Cambridge, and his colleagues found that stem cells are likely to be implicated. During fasting, these cells begin burning fats rather than carbohydrates as an energy source, leading to a boost in their ability to repair damage to the intestines in mice2.
More here.
