A Grain of Salt

Here’s a provocative study – but one that we should maybe take with a grain of salt. It fits the Doc Gurley criteria for interesting studies in that it: 1) deals with a common problem, 2) offers a low-cost, low-risk way of improving that problem, 3) uses an approach that already has known health benefits, and 4) is unlikely to get a lot of press because there’s no drug company profit at stake (so no PR machine to push the issue). So what’s this latest discovery? It’s that reducing salt in your diet may improve your asthma. Who would have thunk it? Even if you (or someone you love) only has exercise-induced asthma, here’s what to keep in mind before you reach for that shaker:

This is a small study (hence the need to take these results with a grain of salt) but has the advantage of being well-designed, and having what we in medicine call “biologic plausibility,” which means that the results fit what we already know (from other sources) about physiology.

24 young healthy people with exercise-induced asthma were given a low-salt diet, then half of them were given a salt capsule to take (without knowing it) and half were given a matching no-salt placebo capsule (also not knowing which it was).  After just two weeks, these people ran as hard as they could on a treadmill and then took sophisticated breathing tests, and had their sputum examined for signs of inflammation.  What the researchers found was that the salt-takers had worse asthma, used their inhalers more, had less oxygen crossing into their blood (which fits the biologic plausibility scenario) and had more inflammation in their sputum. Yeowza. That’s quite a quartet of consistent results, all pointing to the same implication: less salt = happier lungs.

Here’s the nice part of this study – less salt is better for all of us. If you have asthma, this study is a really good reason to cut back on your salt. Here’s the second nice part of this study – there are no side effects to cutting back on salt (except good ones) – isn’t that better (and cheaper!) than adding a new asthma medicine? Maybe you could end up needing less of the medicines you now use (see the Doc Gurley article This Is Not The Time To Suck It Up for more on why you’ll want to be using less of your inhaler – but only as long as you don’t actually need it, that is!).

So how do you eat less salt? First, almost no one can successfully go “salt-free” – not with our usual Western diets. What we in healthcare usually suggest is to taper off – your tastebuds seems to squawk less if you do it that way. First, try cutting back on processed foods. Processed foods are generally the absolute worst for you, so this one’s another benefit to your health! Especially cut back on the processed foods that we all know are salty – salted nuts (buy the low-salt ones first and taper to non-salted ones), pretzels, chips, cans of soup, etc. Start reading labels. You may be surprised at where salt is hiding – studies have shown that American processed foods (including desserts!) have much more salt added than the exact same food in Europe. Also check out websites that evaluate restaurant foods – some restaurant/fast-food dishes have shocking amounts of salt in them. Finally, when you’ve gotten to the point of avoiding high-salt, processed foods, start cutting back on how much salt you add to your meals – until you add none for most foods. For the foods where it seems impossible to eat them without salt (read: eggs, mashed potatoes), ask your doctor about whether salt-substitute is okay for you. There is recent data that shows a health benefit to using salt substitute (see this Doc Gurley post for more on this topic), but salt substitute is not safe for everyone – salt substitute is a large potassium load and some people’s kidneys can’t take that. Some medications also can cause serious problems if you’re eating extra potassium. So check with your doctor before using salt substitute. Then, when you’ve gotten yourself tapered down to a pretty low-salt diet, you may be shocked at how bad some salted foods taste if you accidentally eat them. It’s all a matter of what you’re used to, so set your sights on a lower-salted, easier breathing you.

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