Fasting before and during exposure to Salmonella enterica bacteria, can protect the body from developing a large-scale infection. That's partly due to changes in the gut microbiome.
This has at least been proven through a study on mice published in August 2021 in PLOS Pathogens by Bruce Vallance and colleagues at the University of British Columbia, Canada.
When people or animals get an infection, they often lose their appetite. However, it is controversial whether fasting protects the host from infection, or increases their susceptibility.
In the new study, mice were fasted for 48 hours before and during oral infection with the bacterium Salmonella enterica serovar Typhimurium, a common cause of foodborne illness in humans.
Fasting decreased signs of bacterial infection compared to fed mice, including virtually eliminating all intestinal tissue damage and inflammation.
When the fasted animals were fed again for a day after the fast, there was a dramatic increase in Salmonella counts and invasion of the intestinal wall, although the associated inflammation was still reduced compared to normal. Analysis of the mouse microbiome showed significant changes associated with fasting and protection against infection.
In addition, fasting did not completely protect germ-free mice (cultured with a normal microbiome deficient) from Salmonella, suggesting that some of the protection is due to the effect of fasting on the microbiome. Experiments using the bacterium Campylobacter jejuni confirmed that the effects of fasting were not limited to Salmonella, with similar results seen.
"These data suggest that therapeutic fasting or calorie restriction has the potential to beneficially modulate communicable and potentially non-communicable gastrointestinal diseases," the researchers concluded.
The researchers added that their study highlights the important role that food plays in regulating interactions between the host, enteric pathogens and the gut microbiome.
When food is limited, the microbiome appears to absorb the remaining nutrients, preventing pathogens from obtaining their energy, and needing to infect their hosts.
Although more research is needed, so far fasting or adjusting food intake could be used as a therapy to modulate infectious diseases in the future.