The average temperature of the human body was steadily declining since the mid-19th century, and scholars are not sure why. A new study suggests a key factor that may play a role: gut microbes.
Examination of data from patients who were admitted to the hospital sepsis – where the body reacts dangerously extreme to infection – as well as from tests on mice, the researchers behind the study examined the relationship between gut bacteria, temperature changes and health outcomes.
This selection of sepsis patients is deliberate, as the condition can cause a variety of temperature swings in the body, often related to the likelihood of someone pulling through and recovering.
“We know that the temperature response is important in sepsis because it is a strong predictor of who lives and who dies,” says Microbiologist and immunologist Robert Dickson from the University of Michigan.
“But we don’t know what drives this variation and whether it can be modified to help patients.”
The team examined samples of gut bacteria from 116 people with sepsis and discovered that there were large differences in the microbiota – and that the differences correlated with changes in the patients’ temperature curves.
bacteria from the Firmicutes tribe were most closely related to a higher one Fever. These bacteria produce important substances for body growth and health and influence the body’s immune system and metabolism.
While it’s not enough to show that gut bacteria are the reason our interiors have gotten cooler over the past 150 years, it’s an interesting hypothesis – and it shows how our gut microbiome is related to body temperature.
“It is likely that our patients have greater variation in their microbiota than in their own genetics,” says Internist Kale Bongers, also of the University of Michigan. “Any two patients are more than 99 percent identical in their own genomes, while they can have literally 0 percent overlap in their gut bacteria.”
In further tests on healthy mice with and without a bacterial microbiome, lower base body temperatures were observed in the animals without bacteria – while treatment with antibiotics also lowered the body temperature in the mice.
Furthermore, in both humans and mice, the same family of bacteria appeared to be associated with temperature fluctuations. The next step is to examine more samples from a broader range of people and find out what biological mechanisms underpin this relationship.
With more research, it’s possible we might be able to engineer ways to specifically modify the gut microbiome to affect body temperature — and that, in turn, could improve the outlook for people with conditions like sepsis.
“There’s a reason temperature is a vital sign,” says boner. “It’s both easy to measure and gives us important information about the inflammatory and metabolic state of the body.”
The research was published in American Journal of Respiratory and Critical Care Medicine.
