I am having some pain in my foot due to starting jogging. I decided to reach for Mom’s age-old solution: soak in hot water and Epsom salts.
Which of course made me start to wonder: are there any credible studies showing that it really works? I’ve used it since I can recall and so am inclined to believe that at the very least, it won’t hurt me.
Thanks. I found that link too, but I wasn’t sure it was science-backed.
Yes, magnesium is good for muscles, IIRC, because protein synthesis is heavily dependent on it. In fact, with inadequate magnesium in your system, you may be prone to muscle cramps. It is readily absorbed through the skin, so a bath in epsom salts is a good way to get a dose.
Epsom salts seem to soften the skin and lessen waterlogging. Although often recommended for the easing sore muscles, this effect has never been scientifically demonstrated. It was the “hot water” that seemed to be the active ingredient in the cures.
The relationship of magnesium to protein synthesis as well as and muscle cramping is actually well documented. Magnesium is considered an essential element for athletes, particularly those who do endurance sports where they sweat a lot and throw their electrolytes out of whack. Pregnant women also tend to get cramps from low calcium and magnesium levels. Calcium and magnesium are partners when it comes to muscles contracting and relaxing.
You can look up all sorts of studies on muscle cramps and magnesium deficiency, although you may have to wade through a lot of junk from people trying to sell vitamins.
I’ve also heard that it “draws out lactic acid” which just makes me go :dubious: because I can find no cite than can corroborate that.
I missed the edit window. You’re probably better off just eating more leafy greens and making sure you take your vitamins. What you may absorb probably won’t be nearly as helpful. (I said “readily” absorbed, but “readily” shouldn’t have been there. It is absorbed through the skin, enough for one study to show that there was a noticeable presence, but I don’t recall if the amounts were significant.)
I see you’ve addressed this a little, but I’m curious; do you really absorb salts through the skin to any biologically relevant extent? Most of the chemicals I’m familiar with where skin absorption is an issue are generally non/less-polar solvents like the penultimate DMSO. Not so much with water.
Seems that the charged ions would have trouble permeating all the hydrophobic barriers between skin and blood. But, then, there’s the occasional antiperspirant = aluminum toxicity, so… Any insight? I’m genuinely curious.
But the question is can you absorb enough of it just by soaking in it and not as a supplement?
As a physician, I consider magnesium salts very helpful for a wide variety of things, from pre-eclampsia, to constipation, to Torsades de point. But the key element here is these salts need to be given by IM, IV, or orally to be effective.
Soaking in a magnesium solution may be helpful in that immersing significantly inflamed tissue (such as an ingrown toenail) in a hyperosmolar solution will encourage fluids to pass from the inflamed tissue and out into the soak solution.
But I’ve no reason to think that there’s much benefit when skin is basically intact, even for a badly swollen ankle, unless it’s already weeping fluid before the soak.
Nor would I expect magnesium or other electrolytes to penetrate the very effective skin barrier. Certain drugs can be absorbed thru skin, but the epidermis/dermis is good at excluding most ionic elements from this process.
That’s my view on the topic (following a quick review of med literature on the use of epsom salts as a medication).
(That’s not to say there’s no good therapeutic effect from a nice hot soak on aching bones, joints, and muscles. Quite the opposite, of course. But I consider the effect to be due to local heat. The chief benefit of an electrolyte solution soak is that one is less likely to get all pruney and water-logged)
Yes, soaking in magnesium is an effective supplement. But the water must be hot, and you can do it only a few times a week before the skin refuses to absorb it.
More important than protein synthesis is probably simply that magnesium has a calming, sedative effect. This would relieve muscle cramps, as well as have other positive effects.
One of the main advantages of supplementing through epsom salt baths vs simple ingestion (and there are magnesium pills as well as much quicker-acting soluble powders with names like “Natural Calm”) is that if you eat too many magnesium supplements, even less than the RDA, you’ll shit yourself.
The UK study Alex_Dubinsky is quoting is the one I remember, although I read some of the results back before it was published, in an article that was actually written with the intention of debunking the usefulness of bathing in Epsom salts (but then the author had to admit that science proved him wrong). The author of the article (an RMT, I think) interviewed Dr. Rosemary Waring, who had completed the study, but hadn’t yet published the results. The fact that the subjects’ bodies were absorbing the magnesium through the skin (showing roughly a 10% increase or thereabouts) was a surprise to both the author and Dr. Waring who really didn’t expect it to work.
Apparently, a colleague of Dr. Waring also did some experimenting with pieces of excised human skin (ew, yuck!) which showed that magnesium sulphate can cross it.
At the time I read the article, Dr. Waring had determined that while yes, the magnesium sulfate did diffuse through the skin, she still wasn’t sure how it crossed the stratum corneum. I don’t know if she’s figured it out since.
OK so I’m 30+ years from a general chemistry class, but would the addition of a significant amount of an electrolyte in general change the specific heat of the water to the point that it takes noticibly longer to cool off?
Plain ol’ salt water would do the same thing if I’m right, but the producers of NaCl don’t have the same marketing talent.
Very interesting. I could not find that link using Google Scholar, nor did the use of Google Scholar with those searchterms bring up any further data on magnesium absorption thru the skin. Which surprises me, as Google Scholar is my default search engine for surfing the scientific and medical literature.
I’m rather curious to determine what the mechanism is myself, and also curious about seeing whether that particular experiment that Alex_D pointed out was ever replicated.
Fascinating! The more I learn, the more I realize how little I know…
Me too. And I also wanted to find out more about the “excised skin” experiment because it sounded like it was trying to figure out the “how” part of it. I was under the impression that we’re supposed to be pretty darn waterproof. And now they say I may be leaking? :eek:
It’s quite possible the skin absorbs magnesium by design. This would explain why absorption stops with repeated application. The sea is abundant with magnesium, and there’s no reason organisms haven’t been able to take advantage of that fact since even before they left.
But how and why? Live by the sea, and you get plenty of magnesium in your diet, same as sodium. Live away from it, and run the risk of inadequate Mg and Na in your diet. But sodium doesn’t get transported thru the skin. Nor calcium, chloride, potassium, etc.
You know, this is exactly why I love the dope. I hesitated to even ask the question. I worried it bordered on the “don’t give medical advice” rule and wasn’t sure I’d get any good answers. And now we’re having a pretty interesting discussion. (OK, I recognize that I am playing fast and loose with the word “we”.)