Fasting is becoming increasingly popular, but done incorrectly, it can have adverse health effects. Researchers have been particularly interested in the effects of fasting on the immune system of laboratory mice.
Fasting has the ventvent up! There are different forms: only water or with drinks such as herbal teas and broths or even intermittent fasting in which certain meals are maintained and others deleted. What are the effects of fasting on our health? While occasional, moderate fasting poses no health hazards, what about extended fasts? This is what a research team tried to find out by experimenting with prolonged fasting in mice. Their work has been published in the journal Immunity.
An energy saving mechanism
The authors were particularly interested in the effects of fasting on the immune systemimmune system mice. For these animals, breakfast is the most hearty meal of the day. Barely four hours after skipping breakfast, the body wallwall put in place cost-saving mechanismsenergyenergy. For example, the production of monocytesmonocytes was slowed down: 90% of blood monocytes disappeared after four hours.
Monocytes are white blood cellswhite blood cells key in the immune response in the event of aggression by pathogenic agents. They are normally produced continuously in the spinal cordspinal cord and it is a mechanism that uses a lot of energy. By slowing down their production, the mice’s organism seeks to save energy, not knowing how long it will be deprived of food.
While the mouse is hungry, neurons of its brainbrain trigger the production ofhormonehormone stress, corticosterone. Dropped into the blood, it comes into contact with monocytes. It is a signal that tells the body to slow down the production of these very energy-intensive cells for the body. The monocytes that were circulating in the blood go to the spinal cord to go into hibernation.
And when the next meal comes?
When the mice had food available again, the production of monocytes resumed. And in the end, there were more circulating monocytes than before the fast. Previously hibernating monocytes added to newly produced monocytes. But these ancient monocytes did not have the same abilities as the newly produced monocytes.
Indeed, these old monocytes were more reagentsreagents. In the event of contact with an antigen, they produced an excessive quantity of proteinprotein pro-inflammatory, which can lead to thunderstormthunderstorm cytokine. This sudden excess of inflammation was counterproductive, and these mice had a harder time defending themselves against infections than those that had not experienced a fasting period.
However, these effects were only observed after long fasting times (24 hours for mice, which is equivalent to several days in humans). It is therefore first especially during prolonged fasts that you have to be vigilant.