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Epsom salt and magnesium absorption: what the science says

on September 20, 2016 by John O'Connor

Sleep salts in a bath environment

Updated November 1st, 2016

Do you absorb the magnesium found in epsom salt through your skin?

Yes, you do.

Don’t believe me?

Then read on.

The concept of “transdermal absorption,” the process of absorbing substances through the skin, is not controversial, it’s well established. Our skin is porous, what goes on your skin, ends up in your blood and urine. Transdermal delivery systems for drugs are relatively common. The FDA has approved transdermal drugs for treatment of conditions ranging from testosterone replacement, to nicotine addiction, and even Parkinson’s disease.

However, many pharmaceuticals cannot be effectively administered through the skin, so the research dollars and studies tend to go to orally administered drugs. It’s important to remember, Drug companies decide what to study. There aren’t a lot of drug companies lining up to fund studies on the impact of epsom salt on magnesium, cortisol, or melatonin levels in our bodies.

The dollars drive the studies, which is why articles patronizing epsom salt users as bathing outside of some imaginary “scientific circle of trust” are off base.

A clinical study on epsom salt and magnesium

This clinical study performed at the University of Birmingham, in the UK, shows that people do absorb magnesium by bathing in epsom salt. According to data taken just two hours after subjects took an epsom salt bath, bathing in epsom salt meaningfully increased the levels of magnesium in the blood. 100% of participants had increased magnesium levels after bathing in epsom salt. Three of those participants (out of a total of 19) had increased levels of magnesium in their urine, not their blood. The authors of the study believe this was due to these participants having adequate levels of magnesium before their salt bath, but in all cases the magnesium was absorbed through the skin by bathing in epsom salt. 

Epsom salt is approved by the FDA as a laxative

People forget, epsom salt is FDA approved as a laxative. Why as a laxative? Because magnesium in high enough doses can cause upset stomach, or what Dave Asprey calls “disaster pants.” One of the reasons people use epsom salt baths is because they don’t tolerate oral magnesium. You can read about the elaborate FDA approval process here. Epsom salt would not have approved uses if its magnesium was not absorbed by the skin.

In today’s world of “content marketing,” there’s a lot of pressure on writers to churn out interesting content. Many of the articles that have been done on epsom salt may be successful in fulfilling a content quota, but they’re lacking in terms of analysis. It’s easy to do a quick fluff piece on epsom salt and casually disregard its popularity. 

For example, ABC news did a piece titled the “Truth About Epsom Salt.” Michele Promaulayko, editor-in-chief of Yahoo Health, concludes that epsom salt isn’t “legit,” because “our skin is a protective barrier, it doesn’t just keep the bad things out and let the good things in.”

Hmmm, think that would be news to makers of transdermal drugs.

I think the authors of this study, finding that zinc applied through sunscreen makes it way into our blood streams, would be surprised as well.

Then there’s this study showing that vitamin D can be effectively administered topically through the skin.

What about the FDA? 

The list goes on.

We absorb nutrients, as well as toxins, through the skin. There is a clinical study proving people absorb magnesium sulfate when they bathe in it. Epsom salt users swear by it, because they feel a difference, you don’t need a study to know you just got a great night’s sleep. 

The issue for the skeptics is lack of “conclusive” evidence, but we won’t be getting that anytime soon because there is very little incentive to study epsom salt.