Before the outbreak of COVID-19, humans may have never paid such a high level of attention to "body temperature". The first thing to open your eyes every day is to take your temperature; before entering the mall or restaurant, take your temperature; a little uncomfortable, take your temperature... Under normal circumstances, as long as the measured body temperature is between 36-37 ° C, it will breathe a long sigh of relief.
The level of body temperature, in addition to reminding yourself of whether you have a fever and health, may also tell you, "You are not a long-lived person"!
During the epidemic, dogs also obediently take their temperature
On March 14, a new study published by Nature Metabolism showed that body temperature has a more important effect on lifespan than metabolism, and lowering body temperature helps prolong life. The study was conducted by a team of Professor Zhao Zhijun from Wenzhou University and joined forces with John Speakman's team from the Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences.
First, the researchers conducted the first experiment. They randomly assigned one-month-old experimental mice to two groups for feeding, one group maintaining the feeding temperature at 21 °C and the other group raising the temperature to 32.5 °C. Compare the differences in the length of life of mice with different body temperatures.
The results showed that the average lifespan of female and male striped hamsters at 32.5 °C was shortened by 28.2% and 40.9%, respectively, compared with the suitable temperature of 21 °C. The same was also seen in Swiss mice, where the average lifespan of female and male mice at 32.5 °C was 21.7% and 30.0% shorter than in the 21 °C group, respectively. This suggests that high body temperature leads to a shortened lifespan.
However, common sense tells us that in the case of high body temperature, metabolism naturally increases. Is it because of high metabolism that the lab rat died prematurely?
This is not the case. The attentive reader will find that the researchers have picked a very precise temperature - 32.5 ° C, and the selection of this temperature is very knowledgeable.
Here we have to mention a technical term - Thermoneutral Zone (TNZ). The thermo-neutral zone refers to a certain range of ambient temperature, the animal's oxygen consumption is the lowest, and does not change with the ambient temperature, is a stable metabolic zone.
When small mammals are at the upper limit of the thermal neutral zone or in a slightly higher environment, a decrease in thermal conductivity tends to increase their body temperature. In order to avoid hyperthermia, the body reduces its own thermogenesis by reducing metabolism.
Thermal neutral zone (Source: Baidu Encyclopedia)
For the two experimental animals selected for the study, Swiss mice and striped hamsters, their upper limit of the heat-neutral zone was about 31-32 °C. Although the body temperature of the rats at 32.5 °C will rise, the metabolic rate will remain at a low level.
This is also the perfect temperature the researchers are looking for — body temperature and metabolism change in opposite directions, separating the effects of the two on lifespan.
Therefore, it can be determined that the shortened lifespan of the mice in the study is caused by high temperatures, rather than high metabolism, because the metabolism of mice at 32.5 °C is lower compared to the 21 °C group.
To arrive at more precise conclusions, the researchers conducted a second experiment. They increased ventilation and lowered the body temperature of the mice raised at 32.5 °C, comparing the difference in the lifespan of the rats at different body temperatures at the same 32.5 °C.
They exposed the rats at 32.5 °C to strong winds, lowering their body temperature by increasing heat dissipation. The results showed that the average lifespan of female and male hamsters in the 32.5°C + strong wind group increased by 27.9% and 78.9%, respectively, compared with the original 32.5 °C group, and there was no significant difference between them and the 21 °C group (P>0.05). The same is true in Swiss mice.
That is to say, in the case of keeping the metabolism unchanged, reducing the body temperature of the experimental rat can reverse the effect of high temperature on lifespan, so that the life span of mice can be extended.
Changes in the lifespan of hamsters under different circumstances (gray: 21 °C; red: 32.5 °C; blue: 32.5 °C + strong winds)
In summary, body temperature has a greater impact on lifespan than metabolism, and lowering body temperature helps to prolong life. This result supports the view that "body temperature is a more critical regulator of life expectancy than metabolic rate", and also provides new ideas for future in-depth study of the mechanism of aging and longevity.
However, what is the reason for "high body temperature, early death"? The first author of the paper, Professor Zhao Zhijun of Wenzhou University, said it was not clear why animals died prematurely at high body temperatures. In the future, the team will also delve into the differences in the impact of body temperature and metabolism on lifespan in different ages and between different species.
Summer is approaching, for the sake of longevity, do you know what to do~
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