A Cooling Trend in Body Temperature Which is NOT 98.6 F Anymore!
Research Reveals Drop In Body Temperature In The US
We grew up learning that our body temperature is 98.6 F. But is that really right?
New research by the scientists at the Stanford University School of Medicine says the body temperature in the US has dropped since the early 19th century.
The standard 98.6 F temperature was established in 1851 by a German physician Carl Reinhold August Wunderlich. But recently, a study done in 25000 British patients shows the average temperature as 97.9 F.
The research published in eLife by Parsonnet, MD, professor of medicine and of health research and policy and her colleagues studied the trends in body temperature and came to a conclusion that since the time of Wunderlich, the changes in body temperature follows a true historical pattern. Myroslava Protsiv, a former research scientist at Stanford is the lead author of the paper while Parsonnet holds the senior authorship of the paper. Myroslava is now at Karolinska Institute.
The scientists also added in the paper that the changes in body temperature is the result of environmental changes over the past 200 years.
Digging into the past
The team collected data required for the analysis from three data sets of distinct historical periods. The body temperature data between 1862 and 1930 was captured from medical records, military service records and pension records from Union Army veterans of the Civil War. This included the data of individuals born in the early 1800s.
1971Â to 1975 data was collected from the U.S. National Health and Nutrition Examination Survey I.
Finally, they acquired the data between 2007 and 2017 from the Stanford Translational Research Integrated Database Environment which stores the data of patients who visited Stanford Health Care.
Using the 677,423 temperature measurements, the team developed a linear model that plotted the temperature over time. Previously known facts like increased body temperature in women, in large bodies, in younger people and at later times of the day was confirmed by the temperature trends in the model.
The average body temperature of men born in the 2000s was 1.06 F lower than that of the men born in the early 1800s and the average body temperature of women born in the 2000s was 0.58 F lower than that of women born in the 1890s. These results suggested that the body temperature decreases by 0.05 F every decade.
To exclude the possibility of thermometer errors that could have happened due to the improvements in thermometer technology over the period (thermometry had just begun in the 19th century, it is more accurate today), they studied the temperature trends within each data set. The trends in the veterans’ dataset were similar to that of the combined data.
Although the scientists are confident about the cooling trend, the influence of gender, age and time of day makes it impossible to come up with a new definition of “average body temperature” of the whole Americans.
What could be the reason for the cooling trend in body temperature?
Reduction in the energy being used or in the metabolic rate could be one of the reasons behind the cooling trend in body temperature. The authors also hypothesize that this could be also due to a population-wide reduction in inflammation. The proteins and cytokines produced during inflammation rev up the metabolism and increase body temperature. The drastically improved public health over the past 200 years due to better hygiene, greater availability of food, better medical treatments and improved standards of living have reduced inflammation in the population.
Another reason could be the constant temperature in the environment. People nowadays live a cozy life in houses or offices that facilitates air conditioning and central heating whereas the people in the 19th century had irregular heating in homes with no cooling. The need to spend energy to maintain the constant body temperature is thus removed.
“Physiologically, we’re just different from what we were in the past,” Parsonnet said. The environment that we’re living in has changed, including the food that we have access to, the temperature in our homes and our contact with microorganisms. All these things mean we are actually changing physiologically over the years.
Author : Namitha Thampi
