Supplement analysis backed by scientific evidence · PT

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Magnesium Citrate

The best-supported everyday magnesium form: clearly better absorbed than magnesium oxide, cheap, and widely available. Its main drawback is that it doubles as a laxative, which is either the feature or the bug depending on why you are taking it.

What the science says

  • Better absorbed than magnesium oxide Moderate evidence

    In a 60-day randomised double-blind trial of 46 adults taking 300 mg elemental Mg/day, citrate produced the highest serum magnesium after both a single dose and 60 days, and the highest salivary magnesium, while magnesium oxide was indistinguishable from placebo. An earlier urinary-excretion study put magnesium oxide's fractional absorption at about 4%, versus much higher and equivalent absorption from chloride, lactate and aspartate.

  • Effective osmotic laxative Strong evidence

    Citrate draws water into the bowel; this is why concentrated magnesium citrate solutions are a standard colonoscopy bowel-prep agent. At supplemental doses loose stools begin for many people somewhere above 300-400 mg elemental magnesium per day, which is a real dose ceiling rather than a side note.

  • Not proven superior to other organic magnesium forms Limited evidence

    Head-to-head trials of citrate against glycinate, malate or taurate on clinical outcomes (sleep, cramps, mood) essentially do not exist — the comparative data are almost all against oxide. Choosing between the organic salts is currently a question of tolerability, elemental content and price, not demonstrated efficacy.

Dosage & safety

Studied dose200-400 mg elemental magnesium per day, usually split. Magnesium citrate is roughly 16% elemental magnesium by weight, so a 1,500 mg citrate dose delivers about 240 mg elemental — check labels, since many list the salt weight. Adult RDA for total magnesium intake is 310-420 mg/day; the US tolerable upper intake for supplemental magnesium is 350 mg/day, set specifically on the laxative threshold.
SafetyDose-dependent diarrhoea, cramping and bloating are the common and expected effects. Serious hypermagnesemia is rare in healthy people but a genuine risk in chronic kidney disease (particularly eGFR below 30) — supplemental magnesium should be discussed with a clinician there. Separate dosing by at least 2 hours from tetracycline and quinolone antibiotics, bisphosphonates and levothyroxine, all of which magnesium binds. Not banned in sport.

Scientific references

Where to buy

Double Wood Supplements, Magnesium Citrate, 180 Capsules (400 mg per Capsule)

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