Thursday, August 14, 2014

Dietary salt and high blood pressure

Article: Study questions need for most people to cut salt
A large international study questions the conventional wisdom that most people should cut back on salt, suggesting that the amount most folks consume is OK for heart health — and too little may be as bad as too much. The findings came under immediate attack by other scientists.
From the previous post:
Scientific disciplines are always underpinned by theories that collectively define the dominant paradigm. In the case of modern climate science that paradigm is AGW. It defines the research questions asked, and dictates the methodology employed by the majority of climate scientists most of the time. AGW may be a paradigm with little practical utility and tremendous political value, but it’s a paradigm none-the-less. The world’s most powerful and influential leaders also endorse AGW.
There is also a "high dietary salt causes high blood pressure" paradigm. The paradigm has to be protected from data that oppose it.

The paradigm originated with one study [referred to here] done over 50 years ago. A scientist studied world cultures in order to determine a dietary cause for high blood pressure. It turns out that the Japanese have both a diet high in salt (due to high seafood consumption) and history of high blood pressure. Case closed!

The problem is that even Japanese who do not eat that diet have high blood pressure. High blood pressure among the Japanese appears to be due to widespread genetic factors that dispose Japanese to high blood pressure.

High salt intake was correlated to high blood pressure in both studies. [However, I have read a number of other studies recently that show no correlation. Link goes to Scientific American]
People who consume 3 to 6 grams of sodium a day (about 8 to 15 grams of salt) had the lowest risk of heart problems or death from any cause during the nearly four-year study. More or less sodium raised risk. [Empasis added.] About three-fourths of the world's population is in the ideal range. Americans average roughly 4 grams a day.

Guidelines from various groups for heart disease prevention recommend 1.5 to 2.4 grams of sodium a day. The American Heart Association advises no more than 1.5 grams.
In other words, the AHA's recommendations are so low that they increase the risk of "heart problems or death."

Bad research lead to a pernicious paradigm that will not die, despite decades of opposing research.

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