Magnesium Supplements May Not Reach Your Brain, Whatever the Label Says
Supplement makers claim certain magnesium compounds deliver the mineral straight to the brain, but human studies don't back this up. The cheapest pills, made with magnesium oxide, mostly act as laxatives.
Magnesium supplements are widely sold with labels suggesting they target the brain or muscles. According to an article from Wired, which first appeared in its Czech Republic and Slovakia edition, the science behind such promises is weak.
What the body does with magnesium
The human body typically holds about 25 grams of magnesium, with more than half stored in bones. The rest sits in cells, where it takes part in hundreds of essential chemical reactions, including building DNA and proteins and passing signals through the nervous system. But the fact that cells need magnesium doesn't mean extra will make them work better. Nor does taking more guarantee it reaches the brain or any other specific part of the body.
Absorption is limited
In pills, magnesium is part of a compound known as a magnesium salt. It has to dissolve to release Mg²⁺, the ion the body uses. Absorption depends on the dose, stomach contents and how much magnesium the body already has: the higher the dose, the less is absorbed. Magnesium oxide, the usual basis of the cheapest pills, dissolves poorly, so it mostly works as a laxative by drawing water into the intestines. Magnesium citrate has shown the highest bioavailability in laboratory tests.
Studies and marketing
Some manufacturers claim their particular blend directs magnesium to the brain. These claims often rest on rodent experiments in which animals received magnesium over a long period at higher doses than a pill contains. One rat study found that magnesium L-threonate raised brain magnesium and improved some measures of learning and memory.
A few small randomized trials in people reported gains in some cognitive tests or in sleep, but with caveats: some tested a mixture of substances, lasted only weeks or looked at very few outcomes. Many were funded by supplement makers or led by their staff. None measured magnesium in the brain. So a brain-focused magnesium supplement is, in all likelihood, still just an expensive laxative.
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