High-salt Japanese diet not related to cardiovascular mortality
The Japanese diet has the highest salt level among populations around the world. The Japanese have the longest living population on Earth. Granted, there are lots of confounders, but those are hard facts and relevant to the question of whether low-salt diets are healther and extend life.
A new study, e-published on February 22 in the International Journal of Epidemiology by Taichi Shimazu, et al. reports the results of a seven-year follow-up study of 40,547 Japanese men and women, ages 40-79. The authors identified high blood pressure and high sodium diets as characteristic outcomes of the Japanese diet but concluded that no evidence of any dietary pattern linked to cardiovascular mortality. In fact, the study showed the high-salt Japanese diet to have about 40% fewer CV deaths than in the UK and about 30% less than in the US.
The authors clearly expected another result. They state:
The Japanese diet has so far been considered to increase the risk of CVD because it includes a large amount of salt. In the present study, the Japanese dietary pattern was related to higher sodium consumption and higher prevlance of hypertension. In spite of these risk factors, the Japanese dietary pattern was assocaited with lower CVD mortality.
This is the second health outcomes study of salt intake in Japan. An earlier study found an association between stroke and salt -- but at salt levels much higher than in North America and Europe. In fact, the "low salt" group in that diet had substantially more salt than the U.S. average intake. This study should cause even the high-salt Japanese to consider whether lowering dietary salt will reduce CV risk.
On the other hand, it is yet another study that consistently concludes there is no improvement in health outcomes among populations consuming lesser amounts of salt -- no matter what the government asserts.
