Magnesium is a cofactor in more than three hundred enzymatic reactions, including every one that uses ATP. It is also depleted by stress, caffeine, alcohol, diuretics and low insulin — and modern soil holds less of it than it used to.
The form matters more than the milligrams
- Glycinate — best absorbed, gentle on the gut, and the glycine itself is calming. This is the one for sleep and for anxiety
- Citrate — well absorbed and mildly laxative. The one for constipation, which makes it the default on a low-carbohydrate diet
- Malate — malic acid is part of the energy cycle; commonly used for fatigue and muscle pain
- Threonate — crosses into the brain more readily; the research is early and it is expensive
- Oxide — poorly absorbed, cheap, and mostly useful as a laxative. The form in most supermarket tablets
Dose and timing
Three to four hundred milligrams of elemental magnesium daily suits most adults. Read the label carefully: a 500 mg capsule of magnesium glycinate contains far less than 500 mg of magnesium, because most of the weight is the glycine.
Evening is the sensible default. It is the time the calming forms are most useful, and it is when the citrate effect is least inconvenient.
Why the blood test is nearly useless
Serum magnesium is tightly regulated and sits mostly inside cells and bone. The body will strip magnesium from tissue to keep the blood level normal, so a normal serum reading is compatible with meaningful depletion. Red blood cell magnesium is a better marker and is rarely offered.
This is one of the few supplements where the symptoms are a more reliable guide than the test: cramps, twitching eyelids, poor sleep and constipation all respond quickly if magnesium was the problem.
When to be careful
Kidney disease is the real contraindication — impaired kidneys cannot clear excess magnesium and it accumulates. Otherwise the safety margin is wide, and the usual sign of too much is a loose bowel, which resolves by taking less.
No comments yet