The Science of Transdermal Magnesium Absorption

When you apply magnesium spray to your skin, what actually happens? How does a mineral sitting on the surface of your skin make its way into your bloodstream and tissues? Understanding the science behind transdermal magnesium absorption can help you appreciate why this method of supplementation has gained such popularity—and how to maximise its effectiveness.

In this article, we'll explore the mechanisms of skin absorption, examine what the research tells us about topical magnesium, and address some of the scientific questions that researchers are still investigating.

Understanding Your Skin's Structure

To understand how magnesium is absorbed transdermally, we first need to understand the skin itself. Your skin is not just a simple barrier—it's a complex, semi-permeable organ made up of multiple layers.

The Epidermis

The outermost layer of your skin is the epidermis, which contains several sublayers. The very top sublayer, called the stratum corneum, is composed of dead skin cells (corneocytes) embedded in a lipid matrix. This layer functions as your skin's primary barrier against the outside world—but it's not completely impenetrable.

The Dermis

Below the epidermis lies the dermis, which contains blood vessels, nerve endings, sweat glands, and hair follicles. Once a substance passes through the epidermis, it can enter the bloodstream through the capillaries in the dermis.

How Substances Cross the Skin Barrier

There are three primary routes through which substances can cross the skin barrier:

• Intercellular route: Molecules pass between the cells of the stratum corneum, moving through the lipid matrix that surrounds each corneocyte. This is the primary route for most topically applied substances.
• Transcellular route: Molecules pass directly through the cells themselves. This route is less common due to the multiple barriers presented by cell membranes.
• Appendageal route: Substances enter through hair follicles and sweat glands, which provide direct channels through the stratum corneum. Though these structures cover only about 0.1% of the skin surface, they can be significant for certain molecules.

For magnesium chloride, the exact pathway remains an area of ongoing research, but evidence suggests that the appendageal route (particularly through hair follicles and sweat glands) may play an important role.

Magnesium Chloride: The Preferred Form for Topical Use

Not all forms of magnesium are created equal when it comes to topical absorption. Magnesium chloride (MgCl₂) is the form most commonly used in topical products, and there are good reasons for this preference.

Why Magnesium Chloride?

• High solubility: Magnesium chloride is highly soluble in water, allowing for concentrated solutions that deliver significant amounts of magnesium per spray.
• Ionic nature: When dissolved in water, magnesium chloride dissociates into magnesium ions (Mg²⁺) and chloride ions (Cl⁻). These ions can interact with the skin's natural moisture and biological structures.
• Hygroscopic properties: Magnesium chloride attracts water from the environment, which may help maintain skin hydration and facilitate absorption.
• Natural occurrence: Magnesium chloride is found naturally in seawater and ancient sea deposits, making it readily available and sustainable.

What Does the Research Say?

The scientific literature on transdermal magnesium absorption presents an interesting picture. While the concept of minerals passing through the skin was once considered unlikely, more recent research has challenged this assumption.

Supporting Evidence

Several studies have examined transdermal magnesium absorption with encouraging results:

• A pilot study published in the European Journal of Nutraceutical Research found that participants who applied magnesium cream daily for two weeks showed increased serum and cellular magnesium levels.
• Research on Epsom salt (magnesium sulphate) baths has demonstrated increased urinary magnesium excretion after bathing, suggesting systemic absorption.
• Studies on Dead Sea treatments, which expose the skin to high concentrations of magnesium chloride, have shown physiological effects consistent with magnesium supplementation.

Areas of Ongoing Research

It's important to note that transdermal magnesium research is still evolving. Some scientists argue that more rigorous, large-scale studies are needed to definitively establish absorption rates and optimal application methods. Key questions being explored include:

• What percentage of applied magnesium is actually absorbed into the bloodstream?
• How do factors like skin health, age, and body location affect absorption?
• What is the optimal concentration and application duration for maximum benefit?

While definitive answers to these questions are still emerging, the combination of preliminary research and extensive anecdotal evidence from users worldwide suggests that transdermal magnesium delivery is a viable supplementation method.

Factors That Influence Absorption

Not all skin is equally permeable, and various factors can affect how well magnesium is absorbed transdermally:

Skin Condition

• Hydration: Well-hydrated skin is generally more permeable than dry skin. This is why many recommend applying magnesium spray after a shower or bath.
• Temperature: Warmer skin tends to be more permeable due to increased blood flow and slightly expanded pores.
• Integrity: Intact skin provides a better controlled absorption environment than compromised skin. Avoid applying to cuts or abrasions.

Application Location

Different body areas have different skin thicknesses and permeability characteristics:

• Higher absorption: Inner arms, stomach, inner thighs, soles of feet
• Moderate absorption: Outer arms, legs, shoulders, back
• Lower absorption: Palms, scalp, areas with thicker skin

Contact Time

The length of time magnesium remains on your skin affects how much can be absorbed. Most experts recommend leaving magnesium spray on for at least 20-30 minutes before washing, though many users leave it on overnight with excellent results.

The Role of Magnesium Concentration

The concentration of magnesium chloride in your spray matters. Higher concentrations can deliver more magnesium per application, but they may also cause more intense tingling sensations, particularly in those new to topical magnesium or those with significant deficiency.

Most commercial magnesium sprays contain roughly 25-35% magnesium chloride, which provides a good balance between effectiveness and skin comfort. Some products offer lower concentrations for sensitive skin or higher concentrations for intensive use.

Comparing Transdermal to Oral Absorption

How does transdermal absorption compare to taking magnesium orally? Each method has its advantages:

Oral Magnesium

• Well-established absorption through the gastrointestinal tract
• Easy to measure precise doses
• May cause digestive side effects in some people
• Absorption can be affected by gut health and other dietary factors

Transdermal Magnesium

• Bypasses the digestive system entirely
• Allows for targeted application to specific body areas
• No gastrointestinal side effects
• Absorption may vary based on skin factors

Many health practitioners suggest that transdermal and oral magnesium can work together as complementary approaches, particularly for individuals with higher magnesium needs or digestive sensitivities.

Sources of Magnesium Chloride

The source of magnesium chloride can affect both its purity and its trace mineral content:

• Zechstein Sea deposits: Located deep underground in the Netherlands, these 250-million-year-old deposits are considered one of the purest sources of magnesium chloride in the world, protected from modern environmental contamination.
• Australian salt lakes: Several Australian products source magnesium from pristine inland salt lakes, offering a local alternative with minimal processing.
• Dead Sea: Known for its exceptionally high mineral content, Dead Sea magnesium chloride contains a unique blend of trace minerals.

Conclusion: A Promising Delivery Method

The science of transdermal magnesium absorption, while still evolving, presents a compelling case for topical supplementation. The skin's semi-permeable nature, combined with magnesium chloride's favourable chemical properties, creates conditions that allow for meaningful absorption.

While larger clinical studies would help establish precise absorption rates and optimal protocols, the existing research combined with widespread positive user experiences suggests that transdermal magnesium is a legitimate and effective supplementation method for many Australians.

Understanding the science behind how magnesium spray works can help you optimise your application technique and set realistic expectations for your supplementation journey. For practical guidance on using magnesium spray effectively, explore our beginner's guide or learn about building a daily routine.