Epsom Salts for Muscle Recovery

ARTICLE

Introduction

Epsom salt is a naturally occurring mineral salt formed in the earth’s crust. As the tale goes, it was discovered in the 1600s in Epsom, England by a farmer who noticed that his cows would not drink from a particular spring.^[1,2]  When this spring water evaporated in the summer heat, it left behind a white residue that was later identified as magnesium sulfate (MgSO₄) and given the name ‘Epsom salt’ in tribute to the farmer’s local. This spring soon became a well-known spa as bathers reported that the salt water was especially soothing.

Magnesium (Mg) is an extremely important mineral for our bodies so there is much excitement about the potential health benefits of Epsom Salts.^[3-5] As a focus for this article, magnesium is used to help our muscles relax which matches with the claims of the salt spring’s restorative effect. However, there is much controversy about whether or not we can topically absorb enough magnesium from Epsom salts to have a significant effect. Though it resembles table salt, Epsom salts taste unpleasantly bitter.^[1,2] Ingesting too much can lead to severe vomiting, diarrhea, and other health issues.^[1,3] The safe alternative is for the salt to be dissolved in a bath and absorbed through our skin – this transdermal process has hundreds of years of anecdotal evidence but no strong scientific evidence.^[1,2,6] The question is then, do Epsom salts really work to increase our body’s magnesium levels as many people believe?

Chemistry of Epsom Salts

Epsom salt is a compound formed of two different ions (charged particles): magnesium (Mg²⁺) and sulfate ([SO₄]^2-).^[7] As a salt, MgSO₄ attracts water (ie. is hydrophilic) and is readily dissolved in water or other aqueous fluids like blood. This enables the ions to be easily transported and used once in the blood stream. The hydrophilic nature also influences how the salt interacts with human skin, as discussed below (How Epsom Salts Enter the Body).

Biochemical Role of Magnesium

Magnesium is among the most abundant minerals in the body.^[3,9] Research has shown that magnesium is a key element in hundreds of biochemical reactions important for maintaining muscles, nerves, the heart, blood sugar levels, blood pressure, and more. The exact mechanism of many of these reactions are still under investigation.

Importantly for athletes, Mg helps relax your muscles and alleviate tightness and soreness.^[5] Magnesium is thought to help muscles contract and relax through its role in the Mg-ATP complex, where ATP (adenosine triphosphate) is the energy “currency” molecule of the human body, storing and releasing energy through the formation and breaking of its phosphate bonds. The Mg-ATP complex is used in the sliding filament mechanisms of striated muscle (skeletal and cardiac muscles, as opposed to the smooth muscle of organs). This makes magnesium an essential part of muscle use and recovery. Mg-ATP is also used in other important reactions, including ion transportation and DNA formation (polymerization).^[5]

It is important to ensure we have enough magnesium for our bodies to operate optimally. A lack of magnesium (hypomagnesemia) can cause fatigue, lethargy, loss of appetite, and vomiting, and in more severe deficiencies, neurological issues and cardiac arrhythmias.^[6] On the other end, too much magnesium (hypermagnesemia) can cause diarrhea, vomiting, hypotension (drop in blood pressure), and possible hypovolemic shock if the symptoms progress.^[3]

• Not sure about your magnesium levels? Talk to your doctor to get a blood test!  This can detect magnesium levels, as well as iron, electrolytes, red and white blood cells, and more.

• The Magnesium Fact Sheet for Health Professionals is a good guide to determine how much magnesium your body needs.^[3] However, it is always recommended to speak with a nutritionist or dietician to get personalized nutrition advise. 

Sources of Magnesium

Typically, we get magnesium from our foods such as greens, nuts, seeds and beans.^[3] It is naturally occurring in the earth’s crust and is taken up by plants as they absorb nutrients from their soil and store them in certain parts of the plant. When we eat these plant parts, the magnesium enters our bodies through our digestive system. Other animals intake magnesium in the same way, so we can also get magnesium by consuming some animal products.

• Sources of Magnesium^[3] :   Pumpkin Seeds, Chia Seeds, Almonds, Spinach, Cashews, Peanuts, Black beans, Kidney beans, Edamame, Yogurt, Milk, Salmon, and more!

Epsom salts and topical magnesium creams sold on the market may provide magnesium through the skin, though again, there is no definitive scientific evidence supporting these claims. A surer way to increase your magnesium levels is through food or oral supplements (be careful not to overdo supplements!).

How Epsom Salts Enter the Body

There are two ways in which the magnesium from Epsom salts can enter your system, by (1) ingestion or (2) absorption through the skin.

(1)   Ingestion:  Salts ingested can easily enter the blood stream through the digestive system. However, only a small amount of MgSO₄ is healthy to ingest (usually for use as a laxative). Its bitter taste is a warning to your body of its toxicity. Ingesting too much Epsom salt can lead to severe vomiting, diarrhea, and a drop blood pressure.^[3]

(2)   Skin Absorption:  It is thought that magnesium absorption through skin is a more effective and safe way to intake magnesium, but the scientific evidence is not there to support its effectiveness. Your skin is the largest organ in the human body and serves as a barrier to the environment, protecting against the sun, chemicals, allergens, and microorganisms; it also reduces the loss of fluids and nutrients.^[6] This means that supplement absorption through the skin is limited.

The skin is made up of multiple layers with different composition and properties, with the outermost layer (stratum corneum) having water repelling (hydrophobic) properties – this means it also repels ions such magnesium.^[6] This leads to the assumption that magnesium must be actively brought through the skin via specialized magnesium transporters found at sweat glands and hair follicles which constitute only 0.1% to 1% of skin (though these transporters are still largely under investigation). This would greatly reduce the efficiency of magnesium absorption. Yet, there are still scientific studies which show an increase in magnesium levels through topical absorption, however, these studies have flaws in their small size of test subjects (fewer than 20) or are not peer-reviewed (not reviewed by other scientists, simply published on the internet).^[6] It should also be noted that everyone’s skin is physically different, such as moisture and amount/size of sweat glands and hair follicles, impacting our skin’s ability to uptake magnesium.

In a more optimistic light, these results do suggest that we are likely able to absorb some magnesium through our skin. The question then becomes, can we absorb enough to have a significant impact on our body’s magnesium levels? Hopefully in the future, we will see more rigorous scientific research to show how transdermal magnesium absorption works! 

Conclusions – are Epsom salts worth it?

Magnesium is a vital mineral for our bodies which we typically get in our diet, though supplements are available in both oral and topical (Epsom salt baths, creams, sprays) forms. There is much anecdotal evidence to support Epsom salts as a way to intake magnesium, most notably to soothe sore muscles. However, there is a lack of reliable scientific evidence to back these claims. Given the skin’s anatomy and chemistry of Epsom salts, it is likely that our skin can absorb some magnesium though not in large amounts – this would also depend on a particular person’s skin and time exposed to magnesium. In total, we simply don’t know enough to conclusively say one way or another if Epsom salts work.

I, for one, still love my Epsom salt baths! I also have a magnesium cream (from Be Clean Naturally) that I apply directly on top of sore muscles and I swear it works – when I worked at Be Clean, I also spoke with many customers who swore the same.