Thank you, Carol. I try to share useful information that doesn’t always get much attention.
I do take about 400 mg of magnesium glycinate daily, primarily for its magnesium content rather than specifically for sleep. I chose glycinate for its absorption, although citrate is also well absorbed. The evidence for a sleep benefit is encouraging but still limited.
I also take 4,000 mg of glycine daily for its broader metabolic roles, with its potential sleep benefits as an additional consideration. Small studies suggest it may improve sleep quality, but I’d keep that separate from its established functions in the body.
“Magnesium oil” isn’t an oil. It’s a supersaturated solution of magnesium chloride in water - a brine. The slick feel is the salt itself, which is hygroscopic enough to pull moisture out of the air and off your skin. The tingle people report is that same property working on the stratum corneum, not a signal that anything has gone through it.
And the stratum corneum is the whole problem. That layer exists for one purpose: to stop water and ions crossing in either direction. It is very good at it. Everything that does work as a transdermal - nicotine, estradiol, scopolamine, fentanyl - is small, uncharged, fat-soluble, and dosed in micrograms to a couple of milligrams a day. Magnesium is the opposite on all four counts. Mg²⁺ is divalent, one of the most tightly hydrated cations in biology, and it travels with a shell of water molecules it does not willingly give up. If you set out to design the worst possible candidate for passive diffusion across a lipid barrier, you’d land close to this. And the gap we’re talking about closing isn’t micrograms - it’s a hundred milligrams a day or more.
The human studies are thin: small, mostly uncontrolled, frequently unblinded, and often run or funded by people selling the product. What permeability work exists suggests whatever does get through goes by hair follicles and sweat ducts rather than across the barrier itself - a very small fraction of the surface area you’re spraying.
Here’s the part that connects back to the post. The one measurement that could settle this is serum magnesium, and serum magnesium is exactly the test I spent the piece explaining doesn’t work. So a topical magnesium trial inherits the entire problem: no reliable endpoint, no feedback loop, and therefore no mechanism by which a product that does nothing would ever be found out. That’s the same measurement gap, one layer further out.
It’s cheap, it’s essentially harmless, and if it’s part of someone’s wind-down routine I’m not going to argue them out of it. I’d just file it under “pleasant” rather than “intake,” and get the magnesium itself from food or an oral form where at least the dose is a known quantity.
Your deep understanding of nutrition and how food production affects it is really helpful, not to mention fascinating! I do wonder what your take on magnesium glycinate is, as that particular form is currently the one most recommended for improving sleep.
Thank you, Carol. I try to share useful information that doesn’t always get much attention.
I do take about 400 mg of magnesium glycinate daily, primarily for its magnesium content rather than specifically for sleep. I chose glycinate for its absorption, although citrate is also well absorbed. The evidence for a sleep benefit is encouraging but still limited.
I also take 4,000 mg of glycine daily for its broader metabolic roles, with its potential sleep benefits as an additional consideration. Small studies suggest it may improve sleep quality, but I’d keep that separate from its established functions in the body.
Thank you for responding!
Thank you for your deep dive...any comments on topical magnesium oil?
Thanks for reading it closely enough to ask.
Short answer: I wouldn’t count it toward intake.
“Magnesium oil” isn’t an oil. It’s a supersaturated solution of magnesium chloride in water - a brine. The slick feel is the salt itself, which is hygroscopic enough to pull moisture out of the air and off your skin. The tingle people report is that same property working on the stratum corneum, not a signal that anything has gone through it.
And the stratum corneum is the whole problem. That layer exists for one purpose: to stop water and ions crossing in either direction. It is very good at it. Everything that does work as a transdermal - nicotine, estradiol, scopolamine, fentanyl - is small, uncharged, fat-soluble, and dosed in micrograms to a couple of milligrams a day. Magnesium is the opposite on all four counts. Mg²⁺ is divalent, one of the most tightly hydrated cations in biology, and it travels with a shell of water molecules it does not willingly give up. If you set out to design the worst possible candidate for passive diffusion across a lipid barrier, you’d land close to this. And the gap we’re talking about closing isn’t micrograms - it’s a hundred milligrams a day or more.
The human studies are thin: small, mostly uncontrolled, frequently unblinded, and often run or funded by people selling the product. What permeability work exists suggests whatever does get through goes by hair follicles and sweat ducts rather than across the barrier itself - a very small fraction of the surface area you’re spraying.
Here’s the part that connects back to the post. The one measurement that could settle this is serum magnesium, and serum magnesium is exactly the test I spent the piece explaining doesn’t work. So a topical magnesium trial inherits the entire problem: no reliable endpoint, no feedback loop, and therefore no mechanism by which a product that does nothing would ever be found out. That’s the same measurement gap, one layer further out.
It’s cheap, it’s essentially harmless, and if it’s part of someone’s wind-down routine I’m not going to argue them out of it. I’d just file it under “pleasant” rather than “intake,” and get the magnesium itself from food or an oral form where at least the dose is a known quantity.
Your deep understanding of nutrition and how food production affects it is really helpful, not to mention fascinating! I do wonder what your take on magnesium glycinate is, as that particular form is currently the one most recommended for improving sleep.