Salt connected to obesity?
February 21, 2008
I’ve always said that the research on salt is complicated, not least because it is so difficult to separate out the effects of salt itself from the junk food company it keeps. So a new British study provides some confirming evidence: kids who eat a lot of salt also drink a lot of soft drinks. Guilt by association! The effects of salt on hypertension also might be influenced by everything else in the diet. That’s why it’s so difficult to make sense of research on one dietary factor at a time.
Here in Japan we eat so much salt in the form of soy sauce that stomach cancer is a huge killer. And yet the obesity rate is tiny. So much for that one.
Comment by Mark — February 21, 2008 @ 10:00 pm
Well, we know from standard biochemistry textbooks that the link between hypertension and obesity is not causal; one does not cause the other. Rather, they are both caused by hyperinsulinemia. The same insulin that ushers excess carbohydrate into the fat cells also instructs the kidneys to retain fluid, driving blood pressure up. Anyone who’s ever tried a low-carb diet for more than 1 day can attest to how getting insulin levels down causes the kidneys to get rid of excess water, and people with high blood pressure who try a low-carb diet often find their blood pressure drops like a rock.
So that makes me wonder if excessive carbohydrate consumption, and the attendant insulin spike, can also cause us to crave salt (to balance out the excess water). This is just a wild guess. But when we see these correlation studies, it’s always useful to try to reverse cause and effect, or even try to think of a third factor that could cause both. Maybe excessive salt consumption doesn’t cause obesity. Maybe obesity causes excessive salt consumption. Or maybe hyperinsulinemia causes both …
Comment by Migraineur — February 21, 2008 @ 11:31 pm
Not that there cannot be multiple explanatory variables for the same phenomenon:
I had read that the high incidence of stomach cancer in Japan has been identified as arising from talc-treated rice:
Here is one reference: http://www.sciencemag.org/cgi/content/abstract/173/4002/1141
Myself, I don’t know and have no opinion, but thought the question was intriguing.
On the other hand, a number of articles on Google, suggest that soy sauce confers protection against stomach cancer.
Here is one reference:
http://findarticles.com/p/articles/mi_m1200/is_n23_v139/ai_10911015
Comment by Fentry — February 22, 2008 @ 3:38 pm
My Japanese cookbooks have several recipes using what we call “fiddleheads”–which I have seen at high-end grocer’s.
They have been implicated in cancer and are being studied as a new source of insecticides:
http://en.wikipedia.org/wiki/Bracken
Comment by Fentry — February 22, 2008 @ 3:48 pm
Thanks for the red-hot 1971 research citation from a non-Japanese researcher, Fentry, but we wash our rice, until the water runs clear.
There is a lot of epidemiological research on Japanese stomach cancer. Why cite just one study?
Citation of specific studies is the sign of a crank theory. Citation of meta studies and reviews of the literature is the sign of mainstream science.
Comment by Mark — February 22, 2008 @ 9:48 pm
Fentry: Fiddlehead ferns are part of “yama-no-sachi” cuisine. Japanese eat that maybe once a year or so. I’m glad you can find the ferns in your markets in the U.S., because we can’t easily get them here in Japan.
Comment by Mark — February 22, 2008 @ 9:51 pm
Fiddleheads are also part of the culinary tradition of Appalachia.
I think my posts have been misunderstood. I am not offering them as proof, only as evidence of the diversity of thought on the subject.
The levels of mercury in seafood might also be a useful hypothesis to test in connection to stomach cancer.
While I don’t have proprietary access to many scientific journals, the studies I cited are in the top 10 Google results for “Japan stomach cancer rice” and “Japanese stomach cancer rice.” In other words, these studies are considered the most relevant to people looking at the topic although they are older and were not done by Japanese people.
From what I understand, it is still useful to keep an open mind as the science on this topic isn’t settled.
Comment by Fentry — February 24, 2008 @ 5:30 pm