(ORDO NEWS) — The normal temperature today is slightly lower than that of people who lived 100-150 years ago.
The reasons for this “cooling” are not exactly clear, but new experiments allow us to associate it with changes in nutrition and, as a result, intestinal microflora.
Physicians began to record “healthy” body temperature from the middle of the 19th century, when measurements set it in the range from 36.2 to 37.5 °C.
Since then, this level has been slowly but surely decreasing – by some estimates, by an average of 0.03 degrees per decade.
The reasons for such changes remain a mystery, for the answer to which a number of hypotheses have been put forward.
In particular, it is assumed that the development of hygiene and medicine, the availability of food and a generally more comfortable life led to a weakening of chronic inflammatory processes, which was reflected in a decrease in normal body temperature.
Initially, the team of Robert Dickson (Robert Dickson) dealt with the problem of sepsis – a powerful inflammatory reaction that is caused by the total spread of infection and toxins throughout the body.
One of the manifestations of this condition is unusual changes in body temperature. Sometimes it can instantly jump to a dangerous level, sometimes it practically does not change, other options are possible.
A few years ago, researchers showed that changes in temperature can predict the course of sepsis and its outcome. However, what this or that reaction of the body is connected with is still not clear.
Therefore, Dixon and his colleagues decided to check the state of the intestinal microflora in such patients.
After collecting samples from 116 patients, they found that the change in temperature during sepsis does indeed correlate with the composition of bacteria in the gut.
For example, the presence of bacteria from the Firmicute group was associated with a stronger rise in temperature.
To confirm these findings, the scientists conducted experiments with mice, artificially inducing a state similar to sepsis in human patients.
Two groups of animals participated in the experiments – with the usual microflora, and also completely devoid of it.
Their temperature response turned out to be fundamentally different: in mice with a normal bacterial population of the intestine, a fever quickly began, and rodents with a sterile intestine practically did not react to sepsis.
Moreover, scientists noticed that in animals of the second group, the normal body temperature was slightly lower. Its decrease was also observed after the destruction of normal microflora by antibiotics.
All of this points to the role that gut bacteria can play in maintaining a certain body temperature. Over the past century and a half, due to strong and massive changes in the diet, the microflora has also changed.
Therefore, the authors of the work suggest that it was the bacteria that determined the decrease in body temperature in modern people.
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