Does Epsom Salt Work?

A patient came in earlier this week after an ankle sprain. She hadn't noticed that there was bruising all over the ankle joint. She told me that in order to recover quickly, she'd been told (by someone in a local running store) to soak herself in an Epsom salt bath. This reminded me of the patient who had been asked to take magnesium supplements for muscle cramps.

She was told by the very same person that once her body 'absorbs' the Epsom salt, it can reduce muscle soreness, inflammation and swelling.

So, are there any real benefits to soaking in Epsom salt baths? Or are they just old wive's tales?

You need to know that Epsom salt is also known as magnesium sulfate heptahydrate. It is made of magnesium, oxygen and sulphur. 

The proponents say that using Epsom salt in your bathwater helps your body absorb the 'much needed' magnesium to help flush away toxins and harmful heavy metals and help induce relaxation, reduce inflammation and help with muscle and nerve function. 

Getting magnesium directly into the blood intravenously or even orally is different from sitting in a bathtub and hoping the minerals get absorbed. There is only one small experiment done by researchers from the University of Birmingham in 2006 on some of their staff supporting this. 16 out of 19 of the subjects had higher levels of magnesium in their blood and urine after soaking in Epsom salt for an hour each day over 7 days.  

However Grober et al (2017) failed to find any proof of those claims. The authors also pointed out that the Birmingham study was never formally published in a peer review journal. No statistical tests were done and there wasn't a control group.

There is likewise no evidence that magnesium is absorbed through our skin (transdermal), at least not in relevant amounts scientifically.

Magnesium is an essential nutrient that's actually found in many of the foods we're already eating. It is actually abundant in our bodies. Our bodies need it to create new proteins, for energy production in cells, DNA synthesis etc. As it is essential, our bodies store it in our bones, where it can easily be accessed if needed. Since our bodies cannot produce it, we need to get it from our diet.

Severe deficiencies are uncommon but easy to spot. Symptoms include loss of appetite, vomiting and fatigue and following that numbness, muscle cramps, seizures, personality changes and heart artery changes if the deficiency continues. 

My patient was told that Epsom salt baths can reduce muscle soreness and relieve muscle cramps, that both are very important in exercise performance and recovery.

Please note that magnesium only helps when the muscle cramps are preceded by loss of your appetite, vomiting and fatigue. Not the muscle cramps when you're training hard or racing. Those who sell these supplements, probably choose not to mention this or perhaps they do not know the difference. The muscle cramps occur in your facial and masticatory (chewing) muscles too, not just the muscles in your feet and legs. 

Perhaps it is just the warm water (not the magnesium in the Epsom salt) with its capillary dilation which relaxes and relieves pain for those who seem to swear by it. I feel the water feels more silky after adding a big scoop of Epsom salt to it. The salt exofoliates the skin well too. Perhaps that's a better reason to use the Epsom salt?

References

Grober U, Werner T et al (2017). Myth Or Reality- Transdermal Magnesium? Nutrients 9(8): 813. DOI: 10.3390/nu9080813.

DiNicolantonio JJ, O'Keefe JH et al (2018). Subclinical Magnesium Deficiency : A Principal Driver Of Cardiovascular Disease And A Public Health Crisis. Open Heart. 5:e000668. DOI: 10.1136/openhrt-2017-000668.

*Epsom salt was named after a spring in Surrrey, England that was first discovered in the early 1600's. The waters at the spring were thought to have healing powers and people started to believe that bathing in the waters would relieve them of sores and infections.