There is some question whether the old saying “feed a cold, starve a fever” has much medical validity. Still, it is certainly the case that loss of appetite is one of the ways the body responds to infection. While depriving the body of nutrition as it fights off a pathogen may seem unintuitive, a new mouse study from the University of British Columbia (UBC), Canada, finds fasting may help a body keep enteric - referring to intestinal - infections under control.
The study finds that fasting prevents Salmonella enterica serovar Typhimurium, a leading cause of gastroenteritis in humans, from causing inflammation or tissue damage. The researchers observed similar results with another bacterium, Campylobacter jejuni, suggesting that the study’s conclusions may also apply to other enteric infections.
The study’s senior author Dr. Bruce Vallance said that since previous research on fasting and infection was inconclusive, he and his colleagues hoped to help resolve the question, even if it turned out that fasting helped bacteria thrive:
“This too would be important to know, as therapeutic fasting is becoming more popular for patients with chronic autoimmune or auto-inflammatory diseases. “Of course,” he added, “we would want to know if a therapeutic fast would render the patients more susceptible to infections.”
The value of fasting
The researchers began by treating mice with the antibiotic streptomycin. Previous studies have shown that the antibiotic kills off certain key protective bacteria, helping Salmonella overcome microbiota-based colonization resistance. This creates an environment in which Salmonella can readily expand and cause gastroenteritis. Researchers fed Salmonella Typhimurium to a group of mice that had been fasting for 24 hours, and also to a group that they fed normally. These rodents can safely fast for up to 48 hours.
After an additional 24 hours, the scientists examined the mice to determine the state of their Salmonella Typhimurium infections. In the fed mice, the infection had expanded through the intestine and invaded the intestinal wall, causing tissue damage. In contrast, the researchers found almost no Salmonella Typhimurium in 40% of the fasted mice. In the remaining 60%, the bacteria had expanded through the intestine, although it had done little damage. All the fasted mice exhibited minimal inflammation or tissue damage.
When the team resumed the fasted mice’s normal eating regimen, their Salmonella infections regained their ability to proliferate through the intestine. However, the scientists again observed minimal inflammation or tissue damage.
