<<Disclaimer: Verify this information before applying it to your situation.>>

I didn't do an in-depth analysis of this, but here's a quick once over asking
one important question, as an example of how to read these things.

When a correlational study such as this appears, the first question to ask
yourself is "what could account for the differences in the groups, and did the
researchers control this variable"?  In this case, the obvious question is
"why do people eat differing amounts of salt, and why?"  The 2 obvious answers
are "because they have differing degrees of liking salt" and "because some are
trying to eat less salt for health".  Now, logically, you would expect that
people who had health concerns would be more likely to be in the latter
category than folks who didn't have those concerns.  So we look and see that
yes, they did take history of heart disease into account when they did the
study.  And lo and behold, our first hypothesis proves to be true: more of the
heart disease people are in the lowest salt group and fewest in the highest
salt group.  So people with genuine health concerns *do* eat less salt.

Now, what happened when the researchers looked only at the non-heart disease
folks?

"When the analysis was restricted to participants with no reported history of
CVD at baseline (not shown), both all-cause and CVD mortality were
directly related to sodium/calorie ratio, but the relation did not achieve
statistical significance. "

In other words, close but no cigar.  The majority of the difference between
the groups can be explained by their differing health status. "No statistical
significance" means "better do more studies" and "don't make any
recommendations to the general public", which the reasearchers were very
careful to do, pointing out that the results of their study is NOT a reason
for people to change their dietary habits.  It is interesting, but there are a
ton of unanswered questions, which they prudently pointed out in their
Discussion section.

Naturally, this does not appear in the media accounts, and most people don't
even read beyond the headline "Higher Salt Intake Tied To Longevity".  No
wonder people start to discount medical studies.

Laura Dolson