Magnesium Forms Compared: Glycinate vs Threonate vs Citrate vs Oxide

There's no single 'best' — it depends on your goal. Glycinate for sleep/general use, L-threonate for cognition, citrate for constipation, oxide for antacid/laxative. For absorption, glycinate and citrate are superior to oxide.

Glycinate has high bioavailability (~80% in some comparisons) and minimal GI effects, making it a top choice for general use. It's one of the best-absorbed chelated forms.

L-threonate is the only form shown to cross the blood-brain barrier and increase brain magnesium in animal studies (Slutsky 2010). Human cognitive data is emerging but limited. It's the preferred form for cognitive goals.

Oxide has poor absorption (~4%) and an osmotic effect in the gut, drawing water into the intestines. This causes diarrhea and loose stools. It's better suited as a laxative/antacid than for replenishment.

The RDA is 310-420 mg/day for adults. Many people get less from diet alone. Supplement doses of 200-400 mg elemental magnesium/day are common for those supplementing, depending on dietary intake.

Magnesium taurate provides both magnesium and taurine, both associated with cardiovascular protection and blood pressure regulation. It's a good option for heart-focused goals, though human outcome data is limited.

Yes — combining forms (e.g., glycinate for sleep, citrate for bowels) is common. Total elemental magnesium from all sources should stay within safe upper limits. Consult your healthcare provider.

Citrate has good bioavailability and also supports general magnesium replenishment. Its mild laxative effect is a benefit for constipation but a drawback for others. It's affordable and widely available.

Poor dietary intake, soil depletion (20-30% decline over a century), PPI use (reduces absorption 30-40%), chronic stress, certain medications, and aging. Up to 50% of the US population may have subclinical deficiency.

Glycinate (with calming glycine) is commonly used for sleep support. Magnesium supports GABA activity and may improve sleep quality. Evidence is moderate but consistent for sleep benefits.

Evidence for topical magnesium absorption is limited. Some studies suggest minimal systemic absorption through skin. Oral forms have stronger evidence for raising magnesium levels.

Malate (magnesium + malic acid) is used for energy and muscle pain, including in fibromyalgia. Malic acid participates in the Krebs cycle. Evidence is preliminary but it's a gentle, well-absorbed form.

Standard serum magnesium misses 50-80% of deficiency (only 1% of body Mg is in blood). RBC magnesium is more accurate. Symptoms include cramps, fatigue, poor sleep, and muscle tension — but symptoms alone aren't diagnostic.

Yes — magnesium can reduce absorption of certain antibiotics (tetracyclines, fluoroquinolones), bisphosphonates, and some heart medications. PPIs reduce magnesium absorption. Space dosing and consult your pharmacist.

Chelated forms (glycinate, malate, taurate) bind magnesium to an amino acid/organic acid for better absorption and fewer GI effects. Non-chelated forms (oxide, citrate) have poorer absorption and more laxative effect.