June 03, 2008

Salt, strokes, and regular exercise: it's complicated

[by Merry]

I think all medical studies should be taken with a grain of salt, and maybe with lime and tequila as well. There's one thing a medical study has in common with a Hollywood starlet's Reality Show: it's complicated.

The conventional wisdom has always been thusly:

1. High salt intake = high blood pressure
2. High blood pressure = higher likelihood of strokes and heart attacks
3 Strokes and heart attacks = very bad, to be avoided

I'm fine with points 2 and 3. Point 1 is the questionable part.
This advice is good if you're a couch potato.
It's not so good if you work out a lot . Then the process runs (or walks, or bicycles) more like this:

4. Exercising a lot = sweating a lot
5. Sweating = loss of salt
6. Loss of salt = high blood pressure (refer to points 2 and 3 above)

To quote my hero Dr. Mirkin, from whom this information was blatantly stolen leveraged:

If you exercise heavily and restrict salt, you will not replace the salt you lose through sweating, which can cause high blood pressure as well as fatigue, cramps and muscle pain. When the body is low in salt, the adrenal glands produce large amounts of aldosterone and the kidneys produce renin, which constricts arteries and can raise blood pressure.

Researchers at Albert Einstein College of Medicine showed that people on low-salt diets are actually more likely to suffer heart attacks than those on high salt diets (Journal of General Internal Medicine, June 2008). They analyzed data from the Third National Health and Nutrition Examination Survey (NHANES III) of American adults. Dr. Hillel W. Cohen, lead author of the study, stated, "Our findings suggest that for the general adult population, higher sodium is very unlikely to be independently associated with higher risk of death from heart attacks."

Every time I come across a study that seems to contradict everything I'd heard before on the subject, my first instinct is to go back to bed and pull the covers over my head. Trying to juggle several different theories at one time causes the brain to overload, and I want to press my hands against my ears and sing la la la until all the theories go away.I Just Don't Want to Know.

But sometimes what looks like a 180 degree contradiction isn't. This study refines the previous theory rather than opposing it. You can steer a middle course between no-salt and becoming a salt vampire, like that woman on the original Star Trek. (Am I the only person who remembers the original Start Trek?)

Life is not One Size Fits All, so why should health advice apply equally to all the people all the time? Pass me the tequila and lime. Don't forget the salt.


  1. Hmm, interesting study, and I'd love an excuse to stop limiting salt in my diet. (I'm not very good at it anyway, but I do TRY).

    But I wonder if they looked at people's existing diets, or assigned people randomly into low salt/ high salt groups? Because I'd think in the general population, the folks who happen to be on low-salt diets are often on them for a reason. Like a previous heart attack or family history or high blood pressure or whatever.

    I hope it's true, though!

  2. I get way too much sodium in my diet right now (I like to pretend that when my wolds slows down a bit Ill change. I reside in the Land of Delusion) and figure since I have no need (family history) to immediately cut back I dont.

    yada yada yada Ill seize any reason to make myself feel better.

    thanks for the study!


  3. Interesting! I guess I don't need to worry so much about my own salt intake. I don't add it to food (except cooking pasta) so I mostly get it through my food sources.

    But you know what still gets my goat? Those cans of soup that you eat the whole thing, then look at the nutritional info, only to find out you've eaten all your daily required amount of sodium for lunch. Or twice the daily amount.

  4. I think you are right on, life is NOT one size fits all. I remember running the Salt Lake City half Marathon with my friend Micah, when we crossed the finish line, he had salt deposits on his face from sweating so much. Too often the "medical advice" given is aimed to be true for the vast majority of people, leaving to the side those who do not fit the average... unfortunately, the not average also form a significant chunk of said population...

  5. I tried to restrict my salt intake about 12 years ago after an allegedly borderline high BP reading. I got some nasty cramps after two weeks, ate some salt and they magically disappeared.
    I no longer bother.

  6. I suspect that most of us who eat reasonably healthily aren't at much risk of high blood pressure caused by too much salt. It's the highly-processed junk foods and the additive-laden takeaway meals that are the ones to watch -- not the sprinkling of salt you add when cooking or at the table.

    I vaguely recalled reading something about salt over on diet blog recently, looked it up and found it was actually one of my own posts (so much for my memory!) http://www.diet-blog.com/archives/2008/04/17/is_salt_really_so_bad_for_you.php

  7. Interesting. I eat very little salt as I cook most of my own food & never add salt. I do get really sore from workout though, even when my workout buddies don't. I wonder if adding in a bit of salt would help that? I also have crazzzzy low bp. 80/55 is "normal" for me. Funny that a doc has never mentioned this to me before.

  8. Thanks for this post! I have been cutting down on my salt intake for 6-7 months and got told off by my doctor after a fainting spell. His advice was to go eat some chips the minute I left the clinic. It was interesting to get doctor's orders like that!

    Since then, I add a little salt to things to keep my sodium levels up and no more fainting spells for me.

  9. I'm in the minimize salt camp! I find it tastes bitter now that I'm long un-addicted to it. When I first got my horse, I had a salt block for him. I stopped that early on and he's now "older than dirt!" I still feel that excess salt, sugar, and fat need to be avoided and I'm sticking to it!

    Dr. J

  10. I think excessive = bad in any case. Excessively high or low levels of salt can cause problems.

    And that's a good point that you can get excess salt in your system by eating packaged foods -- and not even know it until you read the label!

  11. Yeah totally. Balance is the key. Margaritas one night and then rice cakes the next.

    I know that I take a daily supplement though to help lower my cholesterol. Have you ever tried Stolle Immune Milk?

    Anyway, its still harder to resist the margaritas than the rice cakes.

  12. Aha!! I always knew it! I have chronically low blood pressure and people still jump on me about how much salt I use. My theory has been that I work out a lot and sweat a lot and I need it. Now I can say that science is on my side!

  13. here here! Life isn't one size fits all! Pour me a shot please! I'm with ya ;-)

  14. Interesting post! I was thinking about that recently. I've been eating a lot of salty snacks lately and noting that I should cut down, but I was wondering if it was really necessary if I'm working out and sweating a lot.

  15. Interesting study...the thing is most people take in WAY WAY more sodium than they need in a day. I'm all for salt pills or sports drinks when hiking and running long distances, but I think of my parents who salt everything to excess and think that's more of who they're talking to when they say salt is bad...
    I've cut back on useing salt as much as I can and still find I get enough through foods and flavourings (*cough* salt and vinegar popcorn flavour *cough*) that I'm OK. I notice I tend to crave salt when I need it and make sure I have some. It could be a concern though if you were an elite athlete or happened to sweat a lot...I guess the point is to make sure a study applies to you before you follow it...

  16. PS-tequila for me too please...

  17. OMG! You are freakin' hilarious! Thanks for making me smile today! i am putting a link to your blog on my page. Gotta get my daily dose of giggles! =)

  18. Does seem complicated alright. I use salt in cooking, but not in huge amounts. I figure a little is ok. As someone else said - I think salt is more of a problem when it comes to packaged/prepared foods, and restaurant meals. Salt is something we need, just not in large amounts.

  19. A few years ago my friend's doctor told her to take salt tablets, because her sodium was too low. WHen she went to the health food store in Harvard Square to buy some, the clerk YELLED at her, telling her there was no such thing as having too little sodium.
    So she left and went to Bread and Circus, where they were much nicer.

  20. I knew a guy once who quipped that eating lots of salt helped to push the fat through his arteries. Sad, but funny.

  21. I eat salt, if I eat too much, my joints let me know by being swollen, so I cut back and things go on as usual.

  22. Dude I KNOW that episode of Star Trek and it's one of my FAVORITES!!!


  23. I agree that theres no one size fits all. Theres so many factors involved that these studies are always so darned hard to figure out! But very, very interesting.

  24. Sometimes the science behind two opposing and seemingly contradictory pieces of health advice IS complex and IS correct!

    I recall that more than once runners have died during the London Marathon due to "dehydration" or loss of salts, but they had actually been drinking LOADS of water .... but as they were losing tonnes of salts through running in the sun, drinking the water was just DILUTING their body salts compsition even further.

    So, sometimes the advice to "drink lots of water" every mile or so whilst running is not the best, the advice needs to be more specific about the water / salt balance in the body and also drinking sports drinks with replacement glucose and salt in them.

    Huh! Look at me! A 300 lb lard arse who seems to be an expert on marathon running -- it's just that I watch it every year (and one year I really do want to take part).

    Thanks for the interesting post.


  25. Hey Sharon, I think that's a good (and serious) example of why this stuff is important.

    And your opinion is as valid as anyone's! Why shouldn't you run a marathon if you want to? Maybe not this year, but still, why not? Pasta Queen started out at 370 something, and she just ran a half marathon!

  26. Contradictory reports? What else is new? As with everything else, moderation is the key. Too much of anything is not a good thing. The tricky part is knowing how much is too much.

  27. I would never believe a study based on a survey. Americans lie there butts off about how badly they really eat. Here it is, eat a wide variety of foods. Salt if you like or not. Workout but don't eat McDonalds every day. The is my wisdom.

  28. The link in the post leads to summaries of several studies. The other one I quoted was done in England and had nothing to do with surveys. Heavy exercise and salt restricted diets caused an increase in blood levels of aldosterone and renin, which led to high blood pressure.

  29. I've always loved salt and my blood pressure has always been on the low side of fine.

    When I started distance running, I quit worrying about salt altogether. If you sweat too much while only replacing water and not salt or other electrolytes, you can get a very dangerous condition which is sometimes fatal.

    I think any so-called common health wisdom needs to be tempered with common sense. If you exercise an hour or longer at a time, you need to be replacing more than just water. And that goes double if you're in the heat!

  30. The specifics of the article may be interesting, but isn't the basic idea of salt not being evil common knowledge? I don't mean to be snotty, but am really asking if people are generally know so little about the necessity for sodium chloride in one's diet?
    I remember years ago reading about how salt is not necessarily the big bad bane of blood pressure as well as about variations of individual requirements for salt (and cholesterol). Even as kids we were told that if we were going to be running around outside in the heat all day we should make sure we got enough salt. We were told the tale of how salt would taste differently according to whether or not we needed it (test it out, we can make a study).
    The idea that someone in a health food store would maintain that there is no such thing as too low sodium is disconcerting.
    Perhaps I should mention that I don't live in the U.S. and don't read many fitness blogs. I bumped into yours somehow and like to read it. You're interesting and fun. I always felt quite sorry for the Star Trek salt vampire.

  31. Naxy, that's not at all a snotty comment -- seems very sensible. And I agree with Bunnygirl -- common sense and moderation are good guidelines.

    I think a lot of people fall into two camps: either they think salt = bad, no exceptions, or they're busy adding salt to their prepackaged sodium-saturated TV dinners. That is merely generalized anecdotal evidence, I have no studies to go by, just my own eyes.

    A lot of people had something to say on this topic, which is cool. And I'm not the only one who watched the original Start Trek! :)

  32. Oh yeah, I was a Trekker! :) The salt vampire freaked me out as a kid.

    I liked the point made about salt tasting different when we need it. It would explain why the first handful of regular potato chips (I usually buy the no salt kind, but cave now and then) is heaven.

    I think a general low salt diet like my family is on is a good idea though. When we indulge in pizza or healthier convenience foods (Trader Joe's say) we know we got salt because we get thirsty. We drink more water and we flush out the salt. Salt if added at all at the table is used judiciously.

    Seems like moderation as usual is the key. Great informative post!


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