Monday, December 10, 2012

Where's the salt?

If you've ever been diagnosed with high blood pressure or you have a family history or condition that puts you more at risk for high blood pressure, you have probably been told to cut back on your sodium intake.  And I'm sure one of the first things that you were told was to put the salt shaker away.  But back in June you might have seen this article pop up in the New York Times questioning that "wisdom" and in my news feed I also saw another article reviewing that there doesn't seem to be a lot of hard evidence stating that merely focusing on the sodium intake does not prevent or help high blood pressure.  So does this mean those who cannot imagine having a meal without the salt shaker are vindicated?  Well, let's look at the evidence.

First of all, in my experience, a lot of people think of these different minerals as existing all by themselves.  When they hear "cut back on sodium" all they can think about is what it's the salt shaker (what I call "table salt" or a combination of sodium and chloride) but they don't necessarily think about what other foods they might also be eating that 1) contain a lot of sodium and 2) affect other systems in our body that regulate our blood pressure.  So a person may be avoiding the salt shaker, but if they are consuming a lot of breads, cured meats, fast food, canned soups, etc you probably haven't really reduced your sodium intake all that much.  So when it comes to good hard evidence that reducing sodium actually influences blood pressure, if we are looking at population studies that use those notoriously unreliable food frequency questionnaires, we maybe don't have a really good idea of how much sodium people really were taking in or how much they  might have actually reduced.  So that is problem number one is that without more double blind studies it's hard to make recommendations.

Now, we are also have to keep in mind that even if we did a double blind study, or if even one person really looks at labels to truly reduce their sodium intake, the people consuming this low sodium diet are going to wind up having to consume a lot less bread/bread products, pizza, fast food sandwiches, sandwiches with lunch meat, fried chicken, canned soups etc as listed in the linked article above.  Since they won't be eating as much processed food, they will probably have to eat meats without any added sodium (fresh meats), real cheeses (not processed), and more fruits and vegetables because they have to fill up their plate with something if they are not eating a ton of pasta at everymeal (or they get a chicken salad as opposed to a sandwich). So, they go from a diet that is sodium/carbohydrate but likely low in fiber/potassium/magnesium/calcium to a diet that is lower in sodium/carbohydrate and likely higher in fiber/postassium/magnesium/calcium.  If people make these radical changes in their diet and their blood pressure goes down--obviously the diet did change something, but it looks like more than the sodium might be at play here.

Keep in mind too that the pressure of blood flowing through your circulatory system is also regulated by a very complex interplay of body systems, and I think does a nice job of making it a little more understandable.  But what you need to know is that these complex systems are also affected by your fluid intake, your mineral intake (sodium and potassium, for example), and yes, your intake of carbohydrate foods.  For people that are already insulin resistant for whatever reason, if they eat too much carbohydrate they are going to have elevated insulin levels which can in turn impact your blood pressure. (Link)  So, if you are someone who has been consuming a lot of processed foods, maybe we do have to worry about your sodium intake, but it looks like your overconsumption of carbohydrate and your lack of vegetables is going to be a bigger problem.

So if you have high blood pressure or are at risk for such because of a family history, etc, before you remove the salt shaker take a long hard look at the rest of your intake.  If you know you're getting more than 30-45 grams of carbohydrate at a meal (that's just a ballpark number now) from bread, etc or you've been eating a lot of other processed foods, that's where you need to start cutting back or cutting out.  And if you know you're not getting a couple servings of fruit per day and non-starchy vegetables at every meal, you probably need to add those back in.  If you are still not noticing a difference in  your blood pressure (or you haven't noticed a reduction in ankle/wrist/abdominal swelling if that is a problem) then you should start using less of the salt shaker and more herbs and spices.  Give yourself a couple weeks to get used to the different tastes of things, and read more about the fascinating history of salt to get yourself in the mood for treating it as a precious commodity.

Take home message--it's your overall diet that will help control your blood pressure if you are at risk.  Concentrate on reducing the amount of processed meats and carbohydrate foods and increase fresh meats and fruits and vegetables.

P.S. Yes, there are certain medical conditions and medications that can cause low blood sodium (aka hyponatremia) but you need to check with your physician first and possibly get lab work done to make sure this actually applies to you.  Competitive athletes might also need to supplement with sodium but I've written before about how that's probably not you.

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