Fasting for 24 Hours Impairs Immune System in Mice

At a glance

• Prolonged fasts can reduce the number of monocytes, a type of white blood cell that helps fight infections
• Monocytes retreat from the blood to the bone marrow during fasting
• Mice that fasted for 24 hours before being injected with a strain of bacteria had greater levels of inflammation and a higher mortality rate
• Most common fasting regimens for humans don’t last 24 hours, and research has shown that a 15-hour fast improves immunity in mice
• Further research is needed to determine the effects of fasting on the human immune system

The details

Fasting Impairs Immune System

Fasting for an entire day can impair the immune system, according to a new study conducted on mice.

Results from the study show that prolonged fasts may reduce the number of monocytes, a type of white blood cell that helps fight infections and recruits other immune cells to treat injury.

Monocytes Retreat During Fasting

When mice fasted for 24 hours, the monocytes retreated from the blood to the bone marrow, where they essentially hibernated.

Upon re-feeding, there was a surge of monocytes.

Fasting Increases Mortality Rate

When the mice were injected with a strain of bacteria that infects the lungs, those that fasted for 24 hours before the injection had greater levels of inflammation and a higher mortality rate than those that never fasted.

Most common fasting regimens for humans don’t last 24 hours, and research has shown that a 15-hour fast improves immunity in mice.

However, the study suggests that fasting for longer than 15 hours may have a negative effect on the immune system.

Further Research Needed

The study’s authors suggest that further research is needed to determine the effects of fasting on the human immune system.

They also suggest that people should be mindful of the potential risks of fasting for extended periods of time.