Fasting may help ward off infections, a new study suggests

Many research studies have investigated the potential health benefits behind fasting, usually exploring the effect on blood pressure, weight loss, and other health points in humans. However, a recent study from the University of British Columbia has explored new ground,  concluding that fasting before and after exposure to Salmonella enterica bacteria prevents mice from developing a full-blown infection. 

The conclusion is based on the discovery that the gut microbiomes of mice change after fasting. The mice were made to fast for 48 hours before and during oral infection of Salmonella, a common foodborne illness in humans. 

We have known for decades that humans and animals alike lose their appetites during an infection, but it has remained unclear whether fasting increases their susceptibility or protects a host from infection. The new study shows that fasting decreased the levels of infection in comparison to fed mice, almost eliminating all inflammation and intestinal tissue damage.

Once mice were re-fed for a day after their 48-hour fast, the presence of Salmonella greatly increased and invaded the intestinal wall. However, inflammation levels that are usually associated with infection were still significantly decreased compared to normal. 

Interestingly, the decreases in infection rates were only identified within mice that were exposed to Salmonella orally, with intravenous exposure showing no effect from fasting. 

Another interesting observation is that fasting did not fully protect mice that were bred to be germ-free, hence lacking a regular microbiome. The researchers recreated the experiment using the bacteria Campylobacter jejuni, and similar results were found. 

The study ultimately suggests that fasting promoted highly beneficial changes within the gut microbiome and that these benefits were transferrable to other bacterial infections and were not restricted to Salmonella alone. 

“These data suggest that therapeutic fasting or calorie restriction has the potential to beneficially modulate infectious and potentially non-infectious gastrointestinal diseases,” concluded lead researcher Bruce Vallance.

“Our research highlights the important role that food plays in regulating interactions between the host, enteric pathogens, and the gut microbiome,” wrote the study authors.

“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. While more research is needed, fasting or otherwise adjusting food intake could be exploited therapeutically to modulate infectious diseases in the future.”

The research has been published in PLOS Pathogens.

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By Calum Vaughan, Earth.com Staff Writer