Fasting may help protect against infection

Study in mice suggests the effect is partly due to changes in the animals’ gut microbiomes

Whether it’s 5:2, 16:8 or Eat Stop

Eat, intermittent fasting diets have skyrocketed in popularity in recent years. Proponents of the diets claim they bring all manner of health benefits, from simple weight loss to significant falls in blood pressure, blood sugar and cholesterol.

Now, a study carried out in mice at the University of British Columbia in Canada suggests that fasting may also help to protect us from infection.

When humans or animals develop an infection, they often lose their appetite. However, it has so far remained unclear as to whether fasting could protect a host from infection or increase their susceptibility to it.

To test this, the researchers fasted a group of mice for 48 hours and orally infected them with Salmonella enterica serovar Typhimurium – a bacteria responsible for a high proportion of cases of gastroenteritis in humans. A second group of mice received regular access to their usual diet before and during infection.

The researchers found that the fasted mice had fewer signs of bacterial infection and very little intestinal tissue damage compared to the fed mice. However, when they repeated the experiment with fasted mice infected with Salmonella intravenously, the protective effect was not seen.

Similarly, the protective effect was not seen when they repeated the experiment using germ-free mice – mice bred to lack a normal microbiome. This suggests that some of the effect was due to changes in the animals’ gut microbiomes.

Many people claim that time-restricted eating or intermittent fasting can lead to health benefits

When food is limited, the microbiome appears to sequester the nutrients that remain, preventing pathogens from acquiring the energy they need to infect the host, the team say.

“We saw an overall change in the composition of the microbiome, meaning an increase in some bacteria and a decrease in other bacteria,” said coauthor Dr Bruce Vallance.

“However, we did not show in our

study which bacteria specifically are

responsible for the protective effect, just that the microbiome as a whole is mediating most of the protective effect of fasting since mice lacking a microbiome – germ-free mice – are not as protected from the infection.”

The researchers now plan to investigate the effect of fasting on the microbiome with the aim of establishing whether the

absence or presence of specific bacteria

are responsible for the protective effect.

“The fasted mice had fewer signs of bacterial infection and little intestinal tissue damage”