Are Japanese Intestines Longer?

The obsession with Japanese uniqueness (biological, cultural, linguistic, geographic, sociological, psychological, etc.) became quite a cottage industry in postwar Japan and is collectively referred to as nihonjinron [1].

[1] https://en.wikipedia.org/wiki/Nihonjinron

You'll find plenty of grains of truth in these works but also some really bonkers pseudoscience ("Japanese are descended from a different set of primates"). It's not a monolithic movement so much as a strain of thought that can color mainstream works to varying degrees as well as popular opinion due to decades of being bombarded with these factoids by Japanese media.

I had always heard that the "longer intestines" story was a myth promoted by the Japanese government during World War II, with the dual goal of promoting the idea of Japanese "uniqueness/superiority" and of discouraging the consumption of meat, which had become very scarce during wartime.

An interesting article, which begs another question. Are the intestines of Japanese bigger compared to those of neighbouring Asians - the Chinese and the Koreans (from whom they apparently descended despite a reluctance to accept this fact) ? This should answer the question of whether it's the genetics at play or the diet itself.

Remember the American doctor mentioned Asian women and not Japanese. Statistically speaking there is a higher chance that the woman with long intestines happens to be Chinese. His comment also brings up another interesting question as to whether the lengths of male and female intestine are different. Why did he mention women specifically?

This is definitely the most surreal article I've ever read on HN....And I think I liked it.

This seems like something that could be settled fairly trivially by a couple of morticians' offices in the west, and in Japan, just by measuring the intestines of the recently deceased for a few months.

I was intrigued by this and did some very quick searching. Here is an article from 1948 which suggests that dietary differences are responsible for longer intestines in Japanese and Russians:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1513781/pdf/anns...

Here is a review which mentions several articles in which investigators looked at intestinal length among westerners and Japanese, but the authors concluded that it was difficult to perform direct comparisons due to differences in measurement techniques.

http://download.springer.com/static/pdf/803/art%253A10.1007%...

When I was in Japan someone offhandedly told me that too, and I thought it was strange. They said it as an explanation of why there aren't massively muscular Japanese men walking around everywhere like there supposedly are in the US (it's probably just because weight-lifting isn't as popular in Japan as in the west).

A really great read. But of all the inquiries and search results only a single one smacked of anything but anecdote

  That led me to yet another Japanese doctor, a man who offered to 
  compare intestinal lengths printed in U.S. and Japanese medical 
  texts. According to him, they were pretty much the same.

A family member of mine with diagnosed Celiac, 50% Dutch 50% German, now dreads his bi-yearly colonoscopies (as he has hit that age) as he has to be fully put under for what is normally an outpatient procedure because his intestines are now unusually long as a result of ~30-50 years of untreated, unknown Celiac. The doctor apparently acted like this is not an unusual thing. No other known factors would produce this result (i.e. my family is not otherwise known for large intestines in the other family members of the colonoscopy age).

This proves nothing specific about the Japanese, but does demonstrate that apparently environmental factors can affect intestine length, and the relevant medical communities consider this boring background knowledge rather than a research topic or urban legend. It is likely in this family member's case that the Celiac only kicked in fully in his 20s, so it is likely all the "environmental factors" occurred in full adulthood (though it is hard to be sure).

(I'm unclear on how long intestines make it harder to digest meat, though. Being overprovisioned for a task does not generally make the task more difficult. I'd find it more likely that it's simply a matter of gut flora adapting to the local diet and not liking deviations. It's the same reason vegetarians can think meat is bad for everybody because when they eat a bit of meat they have a bad, gassy reaction; their gut flora is not adapted for it. (If meat is indeed bad for everyone, that isn't why.) It is easy to be correct about some fact and really, really wrong about the reason behind the fact.)

I feel betrayed. I want a clear answer!

In fact, most of Japanese intestines are shorter than Americans' ones.

The length of intestines are not relating to their races. It's just relating to their height and age.

In 1995, British and Japanese research institutes reported as 'International Colorectal Disease'. In 2004, Tokyo University also reported similar subject. Both reports completely denied the story like "Japanese intestines are 1.5x longer".

I think many Japanese believe this kind of stories, it's because one Japanese drug company made false advertisement to boost their products. After all, this is Pseudoscience.

What a ridiculous article. If you take the most cursory look you'll see that the Japanese have the same length of colons as non-Japanese. While the story itself is interesting, it's irritating that the author doesn't even bother looking at the science.

Question: Do we know that there are any benefits of having longer or shorter intestines? Is the decreasing of elasticity linked to any problems, or is it just muscles that are more worked out and has no effect at all? Is there any research done on the subject at all?

I remember reading a story (at least 20 years ago) that some women in Japan were getting their intestine shortened in order to lighten their skin.

No ghits sorry but from memory once the intestine was shortened the skin started to magically lighten.

This article is totally wrong. In 2004, Tokyo University sampled, and reported in detail. Many Japanese believe this story though. The report completely denied this story.

Japanese and Americans, there are no big differences.

I'm just going to assume that the answer is "no"; otherwise, the title would be phrased as "Japanese intestines are longer" or "Japanese intestines might be longer".

The author refers to the small and large intestine interchangeably and this kind of confusion is no way to start your research.