Magnesium supplement daily dose: forms, benefits, and timing

The short answer: 310–420 mg/day RDA from all sources; most supplements provide 200–400 mg elemental magnesium

Magnesium is the fourth most abundant mineral in the body and a cofactor for 300+ enzymes. Most people get insufficient magnesium from diet (Western diets typically provide ~60–70% of RDA). Supplementation is popular for sleep, cramps, and constipation, and has specific evidence-based roles in migraine prevention and hypertension.

Daily recommended intake (RDA)

| Group | RDA (mg/day) | |---|---| | Adult men 19–30 | 400 | | Adult men 31+ | 420 | | Adult women 19–30 | 310 | | Adult women 31+ | 320 | | Pregnancy | 350–400 | | Breastfeeding | 310–360 |

Upper tolerable intake (from supplements only): 350 mg/day. Dietary magnesium has no upper limit because natural regulation is efficient.

Which form of magnesium to choose

Not all forms are equal — bioavailability and indication differ:

• Magnesium glycinate (bisglycinate): best absorbed, gentle on GI, good for sleep and anxiety. 200–400 mg/day.
• Magnesium citrate: well absorbed, mild laxative effect. Good for constipation + daily supplementation. 200–400 mg/day.
• Magnesium oxide: cheapest, poorly absorbed (~4%), strong laxative. Best for occasional constipation, not for correcting deficiency.
• Magnesium L-threonate: crosses blood-brain barrier, small studies show cognitive/sleep benefits. 1,000–2,000 mg/day.
• Magnesium sulfate (Epsom salt): for soaks (transdermal absorption is limited) or IV use for eclampsia, torsades, severe asthma.
• Magnesium taurate: proposed cardiovascular benefits, less data.
• Magnesium malate: some evidence for fibromyalgia and fatigue.

Evidence-based indications