Stanford study reveals shift in average human body temperature

A new study by Stanford University has revealed that the average human body temperature is decreasing. This challenges the long-standing and widely accepted understanding that the normal human body temperature is 36.6° C (97.88°F).

Dr Julie Parsonnet, an infectious disease expert led a team which analysed copious amounts of data, spanning nearly two centuries and concluded that the commonly accepted average temperature of 36.6° C is incorrect.

Dr Parsonnet’s team at Stanford University worked with 618,306 measurements of oral temperature from adult patients taken between 2008 and 2017. Additionally they also noted the time of day the temperatures were recorded and each patient's age, sex, weight, height, body mass index, medication and health conditions.

Machine learning algorithms were used by the team to eliminate data affected by diseases. The study was published in the scientific journal eLife.

It was found that the normal human body temperatures varied between 36.2° C and 36.8°, suggesting the previously believed normal value is too high.

“Most people, including many doctors, still think that everyone’s normal temperature is 98.6°F. In reality, what’s normal depends on the person and the situation, and it’s rarely as high as 98.6°F,” Dr Parsonnet explained in her statement according to a report by Times of India.

Dr Parsonnet said, “Physiologically, we are simply different from what we were in the past.” The environment that we're living in has changed, including the temperature in our homes, our contact with microorganisms, and the food that we have access to. All these things mean that although we think of human beings as if we're monomorphic and have been the same for all of human evolution, we're not the same. We're actually changing physiologically," she added.

The average body temperature of people in the US decreased by at least 0.05° Celsius which has been attributed to improvements in living conditions and the general health of the population. It can also be because of the metabolic rate.

It was noted that a population-wide decline in inflammation could have contributed to this reduction "Inflammation produces all sorts of proteins and cytokines that rev up your metabolism and raise your temperature," Parsonnet added.

Albeit this change in the average body temperature has implications for diagnosing conditions like fever, which can vary depending on the individual's normal temperature range.