Depending on the type of bacteria present in the gut microbiota, body temperature varies between individuals.
- According to Inserm, the microbiota can harbor more than 1,000 different species, mainly bacteria.
- It is primarily involved in digestion, but it also has an impact on the immune system and inflammation.
Our intestines are home to billions of microorganisms. The whole forms the intestinal microbiota. For several years, scientists have been studying its role in the body. Recently, a team from the University of Michigan demonstrated that it is involved in the regulation of body temperature, both daily and during illness. Their results are published in American Journal of Respiratory and Critical Care Medicine.
Body temperature, a variable data
Body temperature is one of the vital data: “it is both easy to measure and gives us important information about the body, such as its inflammatory and metabolic state”, says Kale Bongers, lead author of this research. What is considered normal body temperature varies from person to person. But the reasons for this variation are still unknown. Previous research has pointed to the potential role of the gut microbiota.
This is why researchers at the University of Michigan wanted examine the interactions between bacteria present in the intestine, temperature fluctuations and their consequences on health. To achieve this, they relied on two elements: data from the medical records of 116 patients hospitalized for sepsis and the results of experiments carried out on mice.
Scientists have become interested in sepsis because this life-threatening infection can cause drastic changes in body temperature. “Previous work has demonstrated that hospitalized patients with sepsis have significantly variable responses to temperature, and this variation predicts their survival.”they specify in a communicated.
A correlation between microbiota and body temperature
One of the first observations of the authors is the high variability of the intestinal microbiota. “We can say that our patients have more variations in their microbiota than in their own genetics.“, explains Kale Bongers. “Two patients can be more than 99% identical in their own genomes, yet they have literally 0% overlap in their gut bacteria.”
They then noticed that this variation was correlated with the patient’s temperature trajectories during their stay in the hospital. “Common bacteria in Firmicutes were most strongly associated with an increased fever responsethey point out. These bacteria are common, vary from patient to patient, and are known to produce important metabolites that enter the bloodstream and influence the body’s immune response and metabolism.” To confirm these results under controlled conditions, the team used mouse models, comparing normal mice to genetically identical mice lacking microbiota. “We found that the same type of gut bacteria explained the temperature variations in both our human subjects and our lab mice.”, develops co-author Robert Dickson. Even healthy mice without microbiota had lower core body temperatures than unmodified mice.
Intestinal microbiota: an explanation for the drop in body temperature?
The authors explain that since the 1860s, the basal body temperature of human beings has continued to drop, for reasons that are still unknown. These new results provide an explanation. “Human genetics haven’t changed significantly over the past 150 years, but changes in diet, hygiene and antibiotics have had profound effects on our gut bacteria.“, recalls Kale Bongers.
