Walk into any health food store or browse supplements online, and you'll quickly discover that "magnesium" isn't just one thingâit's dozens of different compounds, each with unique properties and potential benefits. Magnesium citrate, magnesium glycinate, magnesium oxide, magnesium chloride... the options can be overwhelming.
In this comprehensive guide, we'll break down the most common forms of magnesium, explain what makes each one different, and help you understand why magnesium chloride has become the go-to choice for topical application.
Understanding Magnesium Compounds
Elemental magnesiumâthe pure mineralâdoesn't exist naturally in a form we can easily consume. In nature and in supplements, magnesium is always bound to another compound. This companion compound (called a "salt" in chemistry terms) dramatically affects how the magnesium behaves in your body.
Key factors that differ between magnesium types include:
- Bioavailability: How well your body can absorb and use the magnesium
- Elemental magnesium content: The actual percentage of pure magnesium in the compound
- Side effects: Particularly digestive effects
- Additional benefits: Some compounds offer benefits beyond just magnesium delivery
- Best use case: Different forms are better suited for different purposes
The Major Types of Magnesium
Magnesium Chloride (MgClâ)
What it is: Magnesium bound to chloride, the same salt naturally found in seawater
Elemental magnesium: Approximately 12%
Key characteristics:
- Highly soluble in waterâcreates concentrated liquid solutions
- Excellent bioavailability
- The preferred form for topical/transdermal application
- Also available as oral supplements
- Naturally hygroscopic (attracts water)
Best for: Topical sprays, oils, and baths; anyone wanting transdermal supplementation
Magnesium chloride's exceptional water solubility allows for highly concentrated solutions that can be applied to skin. Its ionic nature when dissolved supports skin penetration. Other forms don't dissolve as readily or aren't as well-suited for transdermal absorption.
Magnesium Citrate
What it is: Magnesium bound to citric acid
Elemental magnesium: Approximately 16%
Key characteristics:
- Good bioavailabilityâone of the better-absorbed oral forms
- Has a mild laxative effect
- Often used for digestive regularity
- Available as capsules, tablets, and powders
Best for: General supplementation; those who also want digestive support
Considerations: The laxative effect can be problematic for some. Start with lower doses.
Magnesium Glycinate (Bisglycinate)
What it is: Magnesium bound to glycine, an amino acid
Elemental magnesium: Approximately 14%
Key characteristics:
- Excellent bioavailability
- Very gentle on the stomachâminimal laxative effect
- Glycine itself has calming properties
- Often recommended for sleep and relaxation
- Typically more expensive than other forms
Best for: Those with sensitive digestive systems; sleep support; anxiety support
Magnesium glycinate is often considered the best-tolerated oral form for those who experience digestive upset with other types. The glycine component may provide additional relaxation benefits, making it popular for evening use.
Magnesium Oxide
What it is: Magnesium bound to oxygen
Elemental magnesium: Approximately 60% (highest of common forms)
Key characteristics:
- Highest elemental magnesium content per dose
- However, relatively poor bioavailability (estimated 4%)
- Can cause significant digestive upset
- Often used as a laxative
- Inexpensive and widely available
Best for: Budget supplementation; those specifically wanting laxative effect
Considerations: Despite the high elemental magnesium content, poor absorption means you may not actually get more usable magnesium than from better-absorbed forms.
Magnesium L-Threonate
What it is: Magnesium bound to threonic acid (a vitamin C metabolite)
Elemental magnesium: Approximately 8%
Key characteristics:
- Specifically developed to cross the blood-brain barrier
- Research suggests it may elevate brain magnesium levels
- Often marketed for cognitive support and brain health
- Generally more expensive
- Lower elemental magnesium means more capsules needed
Best for: Cognitive support; brain health focus
Magnesium Taurate
What it is: Magnesium bound to taurine, an amino acid
Elemental magnesium: Approximately 9%
Key characteristics:
- Good bioavailability
- Taurine itself supports cardiovascular function
- Often recommended for heart health
- Gentle on the digestive system
Best for: Cardiovascular support; those wanting the combined benefits of magnesium and taurine
Magnesium Malate
What it is: Magnesium bound to malic acid
Elemental magnesium: Approximately 15%
Key characteristics:
- Good bioavailability
- Malic acid is involved in energy production
- Sometimes recommended for fatigue and muscle pain
- Gentle on the stomach
Best for: Energy support; muscle pain; those with fibromyalgia (some research suggests benefit)
Magnesium Sulphate (Epsom Salt)
What it is: Magnesium bound to sulphur and oxygen
Elemental magnesium: Approximately 10%
Key characteristics:
- Primarily used in baths rather than oral supplementation
- Traditional remedy for muscle soreness
- Strong laxative if taken orally
- Inexpensive and widely available
Best for: Bath soaks; muscle relaxation; external use
Both are used topically, but they're different. Epsom salt (magnesium sulphate) dissolves in bathwater for soaking, while magnesium chloride is more concentrated and used as sprays or oils. Some research suggests magnesium chloride may be better absorbed transdermally, though both have their advocates.
Comparing Bioavailability
While exact numbers vary between studies, here's a general ranking of oral bioavailability:
- Higher absorption: Glycinate, citrate, chloride, threonate, taurate, malate
- Moderate absorption: Lactate, aspartate
- Lower absorption: Oxide, carbonate, sulphate (when taken orally)
Remember that bioavailability is just one factor. A form with slightly lower bioavailability but better tolerability might still be the right choice for you.
Why Magnesium Chloride for Topical Use?
When it comes to topical magnesium, magnesium chloride stands apart for several reasons:
Exceptional Solubility
Magnesium chloride is highly soluble in water, allowing manufacturers to create concentrated solutions (typically 25-35% magnesium chloride) that deliver significant magnesium in just a few sprays.
Ionic Properties
When dissolved, magnesium chloride dissociates into magnesium ions (MgÂČâș) and chloride ions (Clâ»). These ions can interact with the skin's natural chemistry, potentially facilitating absorption.
Natural Occurrence
Magnesium chloride is the form of magnesium naturally found in seawater and ancient sea deposits. It's been used therapeutically for over a century, including in the famous Dead Sea treatments.
Stability
Magnesium chloride solutions are remarkably stable, with long shelf lives and resistance to degradationâimportant for a product that sits on your bathroom shelf.
Choosing the Right Form for Your Needs
For General Supplementation
Magnesium citrate or glycinate offer good bioavailability with reasonable cost. Glycinate is gentler if digestion is a concern.
For Sleep Support
Magnesium glycinate (calming glycine) or topical magnesium chloride applied before bed.
For Muscle Recovery
Topical magnesium chloride allows targeted application to tired muscles. Magnesium malate is a good oral option.
For Digestive Regularity
Magnesium citrate or oxide (use cautiouslyâcan cause significant loosening).
For Cognitive Support
Magnesium L-threonate is specifically designed to support brain magnesium levels.
For Those with Sensitive Stomachs
Magnesium glycinate or topical magnesium chloride (bypasses digestion entirely).
For Cardiovascular Support
Magnesium taurate combines magnesium with heart-supporting taurine.
Can You Combine Forms?
Yes, many people use multiple forms of magnesium. Common combinations include:
- Oral magnesium glycinate + topical magnesium chloride spray
- Magnesium citrate in the morning + glycinate at night
- Magnesium threonate for brain support + chloride for muscle recovery
If combining forms, be mindful of total magnesium intake. The upper limit for supplemental magnesium is generally around 350-400mg per day from supplements (not counting dietary sources), though some individuals may tolerate or need more under professional guidance.
A Note on Quality
Regardless of the form you choose, quality matters. Look for:
- Reputable brands with transparent sourcing
- Third-party testing for purity
- Clear labelling showing elemental magnesium content
- For topical products, pure magnesium chloride from known sources (Zechstein, Australian salt lakes, etc.)
Conclusion
Understanding the differences between magnesium types empowers you to make better supplementation choices. While no single form is "best" for everyone, knowing the characteristics of each helps you select the right option for your specific needs and preferences.
For topical supplementation, magnesium chloride's unique properties make it the clear choiceâwhich is why it's the form used in virtually all magnesium sprays and oils on the market today.
Ready to explore topical magnesium? Check out our beginner's guide or compare products with our product comparison tool.