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The Japanese Wikipedia states that the average human body temperature is 36.0 °C (here,"ヒト").
The statement references the data from the Japanese government.

Actually all of my Japanese friends think the same.
A body temperature of 37.5 °C is considered a serious illness in Japan, justifying absence from work.

Most other countries' sources cite 37.0 °C as an average.
Is there a biological explanation for this apparent discrepancy?

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nic
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    Here is a somehow related article you might want to read. http://www.health.harvard.edu/press_releases/normal_body_temperature – Remi.b Oct 23 '13 at 06:22
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    Hi Remi.b: Interesting, feel free to propose it as answer! I see two points: 1) Well-accepted means are erroneous 2) Mean depends on the group's age and potentially other parameters. – nic Oct 23 '13 at 07:00
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    I won't pre-empt @Remi.b but the English Wikipedia's got a good breakdown of the variations. – Amory Oct 23 '13 at 13:32
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    36.0 °C is what I was taught when very young, but then it got to 36.8 °C. Actually, my own normal temperature is more like 36.1 °C and I am not japanese. As I literally only had a real fever once in my life, 37.5 °C would be a pretty serious condition for me. For my cousin, who gets a fever with every light cold, it would be kind of normal. So, there is a lot of variation even between related people. – skymningen Oct 25 '13 at 06:44
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    already been answered on http://skeptics.stackexchange.com/questions/10309/do-japanese-people-have-a-lower-body-temperature-than-caucasians – The Last Word Jun 04 '14 at 09:55
  • Related: http://health.stackexchange.com/questions/9981/fever-lower-limit-99-0-f-37-2-c-at-armpit-is-it-universal and http://biology.stackexchange.com/questions/54127/do-human-populations-differ-in-core-body-temperature – Always Confused Dec 13 '16 at 18:40
  • Put every subject(both male & female) in the same environment/conditions, and take multiple temperature readings via oral, rectal, by ear, and under the arm routes. Make comparisons by sex, route of measurement, age, race. As well, the use of different thermometer types, ranging from the old "gold standard" glass mercury rectal thermometer/oral thermometer, thru the digital, ear type and electronic probe types such as FILAC and IVAC with respective oral/anal probes should be considered as there are always questions as to which is the best to use. – Rich Apr 10 '17 at 19:13

4 Answers4

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Factors that can lower body temperature:

  • low environment temperature
  • low metabolic rate
  • hypothyroidism

I couldn't find any relevant study addressing the Japanese people situation, but:

There is significant variation in metabolic rate in humans, independent of differences in body size, body composition, age, and gender. Although it has been generally held that the normal human "set-point" body temperature is 37 degrees C, these interindividual variations in metabolic rate also suggest possible variations in body temperature [1].

And here's a factor that increases body temperature:

The present experiment investigated the effects of skin pressure by foundation garments (girdle and brassiere) on the circadian rhythms of core temperature and salivary melatonin. [...] The results suggest that skin pressure by clothing could markedly suppress the nocturnal elevation of salivary melatonin, resulting in an increase of rectal temperature [2].

Whether there are differences between Japanese and other people in metabolic rate and /or clothing behavior remains unclear.

References:

  1. Rising R, Keys A, Ravussin E, Bogardus C. Concomitant interindividual variation in body temperature and metabolic rate. Am. J. Physiol. 1992 Oct;263(4 Pt 1):E730-4. PubMed PMID: 1415692.
  2. Lee YA, Hyun KJ, Tokura H. The effects of skin pressure by clothing on circadian rhythms of core temperature and salivary melatonin. Chronobiol. Int. 2000 Nov;17(6):783-93. PubMed PMID: 11128295.
Cornelius
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    Kinda surprised this answer got the bounty and is the most upvoted. While it describes factors related to human body temperature, it completely lacks any connection between these factors and Japanese people. It simply does not answer the question. – Nuclear Hoagie May 04 '17 at 13:49
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This entire post is taken from odd thinking: https://skeptics.stackexchange.com/questions/10309/do-japanese-people-have-a-lower-body-temperature-than-caucasians

There may be a difference, depending on whether you are talking about internal or skin temperatures.

This study compared 9 Japanese men to the results of a similar study done in Ohio with Caucasian men:

The subjects were made to walk on a treadmill for 2 hours, in carefully controlled conditions.

There were a number of differences in the amount and composition of their sweat.

Internally, they maintained the same body temperature:

There were no differences in rectal temperature or heart rate, both at the period of equilibrium rectal temperature and at the end of the walk.

However, there were differences in the skin temperature - perhaps not in the direction you were expecting:

Mean skin temperature during the walk was significantly higher in Japanese than in Caucasians.

They concluded that:

the Japanese group was better heat acclimatized than Caucasians, though the two groups were considered to have been naturally heat exposed by season to the same extent.

While this result is suggestive, I don't find it to be definitive, as the caucasians were tested at a different time in a different facility, making them a poor control. Also the sample sizes were small, in an area which may vary by age and other factors.

This study didn't involve Caucasians, but compared Malaysians ("tropical natives") and Japanese males.

They put them under a number of different scenarios, such as soaking their feet in a warm bath, but also at resting.

The results saw that: tropical natives had a higher resting rectal temperature and lower hand and foot temperatures at rest [...]

Glorfindel
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    ok... I put forth the link and you copied and pasted the answer.. What exactly is your contribution? – The Last Word Aug 03 '14 at 08:06
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    meta.stackexchange.com/questions/172307/duplicate-questions-on-other-se-sites @TheLastWord –  Aug 03 '14 at 13:57
  • While the CC licence allows copying the entire post, you still have to make clear which parts of the post are copied. You also have to mention the user that made the original post explicitly in addition to linking to the post. – Mad Scientist Aug 03 '14 at 15:15
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The discrepancy can be partly explained by where the temperature was measured from since the human body temperature ranges from 36.5 and 37.5 °C. For example it is 36.8 ± 0.4 °C when measured under the tongue (http://en.wikipedia.org/wiki/Human_body_temperature). Additionally The body temperature of a healthy person varies during the day by about 0.5 °C (0.9 °F) with lower temperatures in the morning and higher temperatures in the late afternoon and evening, as the body's needs and activities change.

Behzad Rowshanravan
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Suzan Cioc
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    Do you have any references for that (temperature in various parts of the body and methods of measuring in different countries)? It would be quite important to cite them in this case... – nico Mar 30 '14 at 07:50
  • @daniel Where did you read that? – Suzan Cioc Aug 03 '14 at 12:08
  • I was thinking "front" is a part of a head above an eyes: http://en.wikipedia.org/wiki/Forehead Sorry I am not native English. – Suzan Cioc Aug 03 '14 at 22:11
  • Oh! Your English is very good. That's why it didn't occur to me. Cognates are tricky. No problem. – daniel Aug 04 '14 at 00:34
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This study states a 0.35 degrees difference between a japanese and a malaysian, 36.95 and 37.3, it's alot. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3929238/

The following study states states a 0.15 degree difference measured with similar precision, https://www.ncbi.nlm.nih.gov/pubmed/20824480

This graph shows that the human body temperature is 36.2 at rest in the morning/at night and 37.5 in the middle of the day. : enter image description herehttp://millar.bio.ed.ac.uk/andrewM/WE%20book99/Part2-examples.html#tth_sEc8.3.4.2

That may account for the 1 degrees difference in Japanese studies, they measure first thing in the morning/ after 4 hours of fasting and rest/at night, and japanese body temperature of 0.15-0.35 lower that some other ethnic groups.

bandybabboon
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