Over the past 150 years, researchers have confirmed that the average human body temperature has dropped by more than 0.5 degrees Fahrenheit (-0.3 °C). In a new study from the University of Michigan, scientists examining hospitalized sepsis patients found that certain species of gut bacteria appeared to play a role in regulating body temperature, suggesting that changes in these microbes We hypothesized that it might be causing these long-term body temperature fluctuations.
In the mid-19th century, German physician Carl Reinhold August Wunderlich collected millions of temperature readings from thousands of patients over the years. His research eventually found that the average human body temperature is his 98.6°F (37°C). Of course, this is just an average and the normal body temperature range is 97.2 to 99.5 °F (36.2 to 37.5 °C).
Many researchers have since suggested that this average body temperature is a little higher than what can generally be detected in most people. I argued that the calculations were likely correct. Instead, our latest measurements show that the average human body temperature has indeed declined over time.
According to that study, modern human body temperature averages about 97.5 °F (36.4 °C), and has declined relatively consistently every decade over the past 100 years. However, it is unclear why this happened, with various hypotheses ranging from better home heating and cooling reducing overall metabolic rate to better health care reducing inflammation across the population. has emerged.
A new study by researchers at the University of Michigan School of Medicine explores a different hypothesis. Here, researchers investigated the role of the gut microbiota in thermoregulation.
To investigate this, this study focused on hospitalized patients with sepsis. Previous studies have found that clinical outcomes in sepsis patients can be predicted by temperature trajectories during hospitalization. Therefore, in this study, we wondered whether the composition of the gut microbiota at initial admission could predict the trajectory of body temperature.
The study sampled the microbiomes of more than 100 sepsis patients at the time of admission and found distinct gut microbiome patterns that correlated with the trajectory of body temperature during hospitalization. Firmicutes Bacteria were most associated with subsequent hyperthermic responses.
Turning to animal models, researchers found that mice lacking the microbiome had fewer extreme body temperature fluctuations when induced with sepsis compared to mice with normal gut bacteria. According to lead researcher Robert Dixon, the body temperature fluctuations seen in mice may be related to similar bacterial families found in human sepsis cohorts.
“We found that the same type of gut bacteria explained temperature changes in both human subjects and laboratory mice,” Dixon said. “This gives us confidence in the validity of our findings.” It gave us a target to understand the biology behind this discovery.”
So what does this mean? According to lead author Cale Bongers, these findings are good evidence that gut bacteria play an important role in thermoregulation. It may be supporting a slight drop in average body temperature.
“It’s not been proven with certainty that changes in the microbiome explain the decline in human body temperature, but we think it’s a reasonable hypothesis,” Bongers added. Human genetics have not undergone meaningful changes, but changes in diet, hygiene and antibiotics have had a profound impact on gut bacteria.”
This research American Journal of Respiratory and Critical Care Medicine.
Source: University of Michigan
