Sunday, March 24, 2013

Salt over replacement

One of my favorite baseball stats to watch people figure out is the VORP, or value over replacement player.  This stat is an interesting one, in that endeavors to calculate not just how good a particular player is in respect to zero, but rather in respect to how much better the team does with the player in question as opposed to a perfectly average player from the same year.

There's a lot more to it than that, but that's not the purpose of this post.  The purpose of this post is to mention that I would LOVE a similar stat for nutrition research.  Terri put up a post about a new salt study (and gave me a very nice shout out...thanks you!), and it got me thinking about nutrition research in general.

The short version of the study is that researchers collected surveys from 50 countries, took a variety of studies about sodium contributions to disease, and created a model that purports to show how many deaths are due to excess consumption of sodium (2.3 million)

You'll notice I didn't link to the study.  That's because there is no study, at least not one that's published.  This was actually a conference paper that was presented in New Orleans at a cardiology conference.  Now this doesn't mean there's anything wrong with it.  Many researchers use conferences drum up interest/get early feedback on their research (including me).  However, this does mean much of what they did is not yet available, and the peer review process is much less stringent.

That being said, there's not much to criticize* without the details (except the headlines about it, those are awful), but it did get me thinking about the point of all of this.  I don't know exactly what countries were covered, or what the major sources of sodium  in their diets were.  It strikes me though, that for at least some of the people in these countries may not have a terrible amount of choice in the high sodium foods they're eating.  If sodium is being used to say, preserve food, or if processed (and shelf stable) foods are a big source of calories, or if salt is being used to make vegetable consumption more palatable, could campaigning to reduce it do some harm?

In nutrition research, we can't just think about what we shouldn't be eating, but also why we eat those things.  Salad dressing is a decent source of sodium in my diet, but I can guarantee I wouldn't eat as many veggies if I had to stop using it.  Does the benefit of the vegetables outweigh the detriment of the sodium?  What is the value over replacement?  When the low-fat craze hit, many people replaced fat in their diet with sugar.  A few decades later, the general consensus is that this was a bad idea.

The fundamental assumption of a study like this is that you can subtract one part of your diet separate from any other piece.  In my opinion, what we really need is a study where you at least explore that people can reduce their sodium without otherwise worsening their diet.  This critical piece seems to be missing from many nutritional public health initiatives.  It's important though...every dollar spent on an initiative to reduce sodium doesn't get spent elsewhere.  Proving something in a vacuum has to be followed by research proving it in the real world, otherwise you risk unintended consequences.   A little vice can be good for the soul.

*Okay, I'll take a shot anyway.  There's some question about how much good sodium reduction actually does, and I'm really curious how they controlled for racial differences in response to sodium levels.  

1 comment:

  1. So, if salt is replaced in packaged food, what would it be replaced with?

    One of the properties of salt is a preservative.

    Another is flavor.

    What additives would be used for those purposes?