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Take that with a grain of salt

Is Salt Really as Bad as THEY Say it is?

by Alex Boersma

We all know that salt is bad for you.  We’ve heard it since we were kids.  Most of us can probably remember our mothers taking the salt shaker away from our pot-bellied fathers, chastising them for risking their lives by putting SALT on their food.  Today, the venerable salt shaker has gone missing from the every-day dinner table.  Sure, it still makes the occasional guest appearance at Thanksgiving and Christmas dinner, but even then, we try to put our hands on it only when nobody else is looking.

Most people accept as a given that salt consumption causes high blood pressure and heart disease.  As somewhat of a health skeptic, I have for some time had concerns about the certainty with which this salt – blood pressure – heart disease link is proclaimed.  But because of the strength of the consensus on salt and the lack of solid evidence refuting said link, I have kept my reservations to myself.  In the past year, however, the controversy over salt has reached a crescendo in the medical journals and has even spilled over into the more mainstream media.  It is time to come out of the salt closet and take a stand.  It is time to give the salt – blood pressure – heart disease hypothesis the licking it deserves.

salt lick

Licking the salt hypothesis

Let’s begin with what the science says.  Here are the conclusions of a recent meta-analysis of prospective studies into the relationship between salt consumption and cardiovascular disease:

 ”High salt intake is associated with significantly increased risk of stroke and total cardiovascular disease.”

Compare that quote to this study, which seem to have come up with an entirely different set of conclusions:

“…a sodium excretion of less than 3 g per day (most health authorities recommend between 1.5 and 2.5 g/day) was associated with increased risk of CV mortality and hospitalization for CHF (coronary heart failure)

Similarly, a recent Cochrane analysis  indicates that although salt restriction may minimally reduce blood pressure in some people, it also negatively affects a number of hormones responsible for regulating blood pressure and kidney function while simultaneously increasing both total cholesterol and triglyceride levels.

WHAT GIVES?

A recent article in Scientific American entitled “Its Time to End the War on Salt” outlines the problem.  As usual with medical/scientific consensus, the burden of proof behind the salt hypothesis is found to be seriously wanting.  The idea that salt causes high blood pressure originated with a 197o’s researcher named Lewis Dahl who proved that if you feed rats 100 times the human equivalent of recommended salt intake, then, surprise surprise, their blood pressure goes up.  Since then, a number of prospective studies (remember prospective studies – otherwise known as epidemiology – otherwise known as interesting for making observations but absolutely useless for proving anything!!!) have come up with a number of ambiguous results which kinda/sorta/maybe support Dahl’s conclusions.  The meta-analysis quoted above is just a summary of the findings from all these kinda/sorta/maybe studies.  And if you actually read the study, you will see that although the association between salt intake and vascular disease is, indeed, significant from a statistical perspective, it is by no means impressive from a “how does that affect me” perspective.  Very few of the studies included had significant results of any kind, but when the researchers pooled them all together they were just barely able to eke out some statistical significance.  In the end, if you participated in one of these studies, you had about a 6% chance of having a heart attack or stroke, regardless of how much salt you ate. But if you were foolish enough to eat a high salt diet while participating in one of these studies, you had about a 7% chance of having a heart attack or stroke.  Statistically significant?  Sure.  Significant enough to warrant foregoing the venerable salt shaker?  Not so much!

And remember, none of these studies were intervention studies.  The researchers weren’t exactly feeding people an extra tablespoon of salt every day to see what happened to them.  Instead, they were merely measuring how much salt was in each person’s regular diet. What kind of regular diet is a high salt diet?  How about a fast food diet, or a highly processed diet?  And what kind of people eat highly processed or fast food diets? How about really busy people, stressed people, poor people, or people who just couldn’t give a lick of salt about the quality of their diet?

salt

If you have a high salt diet, chances are you also have a high crap diet!

Any chance that might confound the study results?

The truth is that most of us have these organs called kidneys which, if they are working properly, should be able to adapt to a wide variety in salt intake.  Sure, if you spend your day eating olives, beef jerky and potato chips, there is a good chance you might wake up the next morning spitting tumbleweeds and looking like a puffer fish.  But if you keep it up with the olives, jerky and chips, there is also a good chance your kidneys will adjust to the increased salt intake and start sending all that salt (and water) through your bladder instead of your skin.  It is only when your kidneys (or at least the hormones that control your kidneys) stop processing the salt appropriately that the extra salt starts messing with your blood pressure.  Ironicly enough, low levels of salt intake (down below 2 grams/day…around where the salt dictocrats want your salt consumption to be) are more likely to mess with hormonal control of salt than high levels of salt consumption.

Even more ironically, the advice to severely restrict sodium intake  if you are at moderate to high risk for heart disease may be doing a lot more harm than good.  In this study, patients undergoing treatment for congestive heart failure were 3 times more likely to get re-admitted if they were on low salt diets, and 2.5 times more likely to die.  Out of 114 low salters, 15 were dead after 6 months.  Amongst the 116 high salters, only 6 were dead after 6 months.  Now that’s what I call significant!  And remember, this was a randomized controlled study…you know, the kind that actually means something!

In a similar vein, it seems that patients with type 1 diabetes and type II diabetes do not thrive on low salt diets. Granted, these are epidemiological studies, but still?  I’m not saying that low salt diets are killing diabetics, I’m just saying that they don’t seem to be doing any good.  And for diabetics – who are notorious for developing heart disease - maybe the focus should be on losing weight or getting active, two interventions which have proven to be much more effective than making your food taste like cardboard. 

Furthermore..it seems that there are more minerals involved in blood pressure modulation than sodium alone.  It seems that potassium is at least as important as sodium, while the ratio of sodium to potassium seems to have a much more significant association with heart disease than sodium on its own.   As this Archives of Internal Medicine paper concludes, “A higher sodium to potassium excretion ratio is associated with increased risk of subsequent CVD, with an effect stronger than that of sodium or potassium alone”. 

Here’s the thing.

As with just about anything in the field of nutrition and health, the association between salt intake and disease can be described by a J or U curve.  We know for sure that consuming less than 800mg of sodium a day is associated with negative health outcomes.  Likewise, we know for sure that consuming more than 8 grams of sodium a day is associated with negative health outcomes. In between, there is a curve which is by no means clearly defined.  It probably looks something like one of these:

sodium and health curve

from JAMA. 2011;306(20):2229-2238. doi:10.1001/jama.2011.1729

Again, this is just epidemiology, but since the whole “salt is bad for you” hypothesis is based almost entirely on epidemiology, I just don’t get where these associations lead us to believe that sodium should be restricted below 2 grams per day.  As you can plainly see, all the graphs above show less cardiovascular disease around 4 g/day than below 2g/d.  Even strokes, which seem to react best to low sodium, are for some reason less frequent around 6g/day than they are around 2g/day.

Don’t get me wrong!

There are certainly people who’s blood pressure reacts catastrophically to a high salt diet.  This reaction seems to be genetically programmed.  Black people, for example, do not seem to do well with excess sodium.  Perhaps they evolved in an environment where the ability to conserve sodium was much more highly developed than the ability to excrete it.  Likewise, other races and other individuals probably also have less tolerance for salt.  People with kidney disease and possibly those with kidney stones should probably be careful with salt.  The point is, if your blood pressure is chronically elevated, lowering your sodium intake is certainly a worthwhile way to try and bring it down.

But it is by no means the only thing you should be doing!  I can’t tell you the number of people I’ve heard of who spend 3 months on a low salt diet and then jump directly to blood pressure medication.  If I was more inclined to theorize conspiratorially, I might suggest that the medical community places so much emphasis on salt because it knows salt reduction will be ineffective for most people and it will then be able to convince these same people to spend the rest of their lives on highly profitable blood pressure medication.  Let’s not go there!  The more likely explanation for this mostly futile assault on flavour is that salt is an easy target.  We all know that nobody heeds advice to eat less, move more, forgo processed food, eat plenty of fruits and vegetables and reduce stress.  What, those things actually work to decrease blood pressure and reduce heart disease?  Never mind, people won’t do those things anyway!  Let’s just tell them to eat less salt, and if that doesn’t work, there are always statins, diuretics and ACE inhibitors!  We can even give the food processors little check marks and hearts on their packaging if they bring their sodium content down.  Sure they will replace the salt flavour with sugar and artificial flavour, but if people get sick from these things, perhaps we can sell them some more pills to deal with whatever ails them.

Oh yeah, I said we weren’t going to go there.

Salt makes bland food taste good.  Broccoli tastes like cardboard.  Steamed broccoli tastes like wet cardboard.  Steamed broccoli with butter and salt tastes like candy!  Real health, as far as I am concerned, depends on the consumption of real food.  If adding salt to your diet means eating more real food and less processed crap, I say “pass the salt”.  I contend that, for most people, it is not the salt in their food which is giving them high blood pressure.  It is the food in their salt!  In ”Supersize Me”, Morgan Spurlock’s blood pressure rose from 120/80 to 150/90 after eating nothing but McDonald’s food for a month.  But was it the high sodium in the diet which caused his blood pressure to skyrocket, or was it the fact that he was eating over 5000 calories a day of nutritionally devoid processed food, ballooning his weight while turning his liver into foi gras?

The problem with the low-salt agenda is not so much the lack of supporting science or the possibility that it might be doing more harm than good.  The problem with the low-salt agenda is that it takes the focus off the righteous culprits in hypertension.  Salt consumption is, for most people, at best a minor factor in the control of blood pressure. You want to keep your blood pressure down?  That’s simple.  Eat real food, maintain a normal body weight, be active daily, and reduce or control stress in your life. 

 OK.  I didn’t say it was easy, I said it was simple. 

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