Tuesday, June 05, 2012

Salt: Bad, Good, or We Don't Know?

The following article was the most emailed of last Sunday's New York Times, and is worth a read:

We Only Think We Know the Truth About Salt - NYTimes.com

The questions on the "clear" relationship between high salt intake and mortality are not new.  The article speaks about some of them, but even I remember these questions being raised.  When I was a freshman studying nutrition at Cornell, my introductory nutrition professor, David Levitsky, raised doubts about salt's connection to poor health.

In my favorite class at Cornell, "Mineral Nutrition and Chronic Disease," taught by Charles McCormick, we spent weeks delving into the literature on sodium, blood pressure, and heart disease.  As I left the class, I had serious doubts about the link.  There were clearly some salt-sensitive people with high blood pressure, for which salt reduction reduced their numbers.  But should we reduce the whole population's salt intake?

Still, I thought that even if the benefit of reducing salt was small on an individual level, the population benefits were likely large.  Even a small reduction in everyone's blood pressure could probably prevent deaths.  So in medical school I worked on a petition to the FDA, filed by CSPI, to limit salt in foods.

Now, even if salt itself is not a cause of increased mortality, it may be a marker of something else: poor eating habits.  Maybe the people who eat salt just eat a long of junk food.  Maybe limiting salt would still be a good thing, as people will drink less sugary beverages to quench their thirst.  But it may be prudent to have more research on this public health policy before we cause harm.

We do not want salt to go the way fat went: It was bad, and then it was good.  One thing I know is good: make sure 1/2 of every plate is vegetables and you are walking daily.
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