Human body temperature has been decreasing
[2020-06-30]
Interesting finding reported by Prostiv et al. earlier this year [1] - human body temperature has decreased in the US since the Industrial Revolution. The authors suggest the change is due to a reduction in chronic inflammation:
"Although there are many factors that influence resting metabolic rate,
change in the population-level of inflammation seems the most plausible
explanation for the observed decrease in temperature over time. Economic
development, improved standards of living and sanitation, decreased
chronic infections from war injuries, improved dental hygiene, the
waning of tuberculosis and malaria infections, and the dawn of the
antibiotic age together are likely to have decreased chronic
inflammation since the 19th century.
...
Reduction in inflammation may also explain the continued drop in
temperature observed between the two more modern cohorts: NHANES and
STRIDE. Although many chronic infections had been conquered before the
NHANES study, some—periodontitis as one example (Capilouto and Douglass, 1988)— continued to decrease over this short period. Moreover, the use of anti-inflammatory drugs including aspirin (Luepker et al., 2015), statins (Salami et al., 2017) and non-steroidal anti-inflammatory drugs (NSAIDs) (Lamont and Dias, 2008)
increased over this interval, potentially reducing inflammation. NSAIDs
have been specifically linked to blunting of body temperature, even in
normal volunteers (Murphy et al., 1996).
In support of declining inflammation in the modern era, a study of
NHANES participants demonstrated a 5% decrease in abnormal C-reactive
protein levels between 1999 and 2010 (Ong et al., 2013)."
I am wondering if or how this relates to the 'hygiene hypothesis' (though it should not be called such [2]). Also, does this mean that ion futile cycling / Na/K ATPase activity is decreasing? Are there any historical studies of epigenetic changes over this time period - is it even possible to conduct such a study with preserved tissue samples? Does this finding relate to the Flynn Effect?
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1 -
Protsiv, Myroslava, Catherine Ley, Joanna Lankester, Trevor Hastie, and Julie Parsonnet. “Decreasing Human Body Temperature in the United States since the Industrial Revolution.” ELife 9 (January 7, 2020). https://doi.org/10.7554/eLife.49555.
2 -
Scudellari, Megan. “News Feature: Cleaning up the Hygiene Hypothesis.” Proceedings of the National Academy of Sciences 114, no. 7 (February 14, 2017): 1433–36. https://doi.org/10.1073/pnas.1700688114.
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