Fasting for 24 hours could weaken the immune system

Mice fasted for 24 hours had more inflammation and were more likely to die of bacterial infection than mice on a normal diet schedule.

To Grace Wade

Fasting was previously proposed as a useful approach to prevent or manage chronic diseases such as cancer, obesity and heart disease, but studies in mice have shown that prolonged fasting can compromise the immune system. has been shown to have potential.

Filip Swirski and his colleagues at the Icahn School of Medicine in Mount Sinai, New York, analyzed blood and tissue samples from five mice that had been deprived of food for 24 hours. Blood tests comparing these mice with those fed a normal diet showed that, on average, the fasted mice had less than 10% of the monocyte counts. Monocytes are a type of white blood cell that recruits other immune cells to fight infections and treat damage. .

“These cells are very important foot soldiers for the immune system,” says Swirski. Researchers have found that monocytes are declining because they retreated from the blood to the bone marrow, where they essentially hibernated, he says.

As a result, when the fasting mice were re-fed, the monocytes returned to the bloodstream. ,” says Swirski. “So when you re-feed, you see a spike in monocytes.” These mice had, on average, about four times as many monocytes in their blood compared to mice that were either continuously fasted or not fasted at all. .

To understand how this affects immunity, he and his team injected 45 mice with a bacterial strain that infects the lungs. Twenty-three mice were fasted for 24 hours prior to injection. The researchers then gave them access to food.

After 72 hours, approximately 90% of fasted mice had died and approximately 60% of non-fasted mice had died. Diet-fed mice also had higher levels of inflammation, suggesting that prolonged fasting impairs the immune response.

However, Satchidananda Panda of the Salk Institute for Biology in California says that most common fasting regimens in humans do not last 24 hours. It has been shown to improve strength.

Still, says Swirski, these findings are important for how we think about the duration and meaning of fasting. , which may be beneficial in some ways, but can have unexpected adverse effects in others,” he says.

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