Evidence explainerMagnesium glycinateMagnesium citrateMagnesium
Magnesium Glycinate vs Citrate: The Calm One, the Bathroom One, and What the Label Really Holds
Glycinate is the bedtime favorite; citrate has a reputation for keeping you regular. The evidence for each is thinner and more interesting than the marketing, and the elemental math changes how much you are really getting.
Key takeaways
- By weight, magnesium glycinate is about 14.1% magnesium and citrate about 16.2%, and US Supplement Facts panels list the elemental amount [1][2].
- Citrate is more soluble and more bioavailable than oxide in short studies; in a 60-day trial of 46 people it produced the highest serum magnesium of the forms compared [3][4].
- Glycinate matched oxide on overall absorption in a 12-person crossover study, did better in the 4 people who absorbed oxide worst, and was better tolerated [5].
- For sleep, one 4-week trial of magnesium bisglycinate (250 mg/day elemental) in 155 poor sleepers found a small drop in insomnia scores (3.9 vs 2.3 points) [6].
- The adult upper limit for magnesium from supplements is 350 mg/day; diarrhea was reported by 18.6% of people taking 600 mg/day of citrate in one trial [1][7].
Safety at a glance
From our Magnesium glycinate monograph. Published interactions and cautions only, each with its source.
Interactions
- Oral bisphosphonates. Magnesium-rich supplements or medicines can reduce bisphosphonate absorption; NIH ODS notes separating them by at least 2 hours.[1]
- Tetracycline and quinolone antibiotics. Magnesium can form insoluble complexes with these antibiotics; NIH ODS notes taking the antibiotic at least 2 hours before or 4–6 hours after magnesium.[1]
- Potassium-sparing diuretics. Reduce urinary magnesium excretion.[1]
- Loop and thiazide diuretics. Long-term use can increase urinary magnesium loss and lead to depletion.[1]
Who should be careful
- Kidney problems. The risk of magnesium toxicity rises with impaired kidney function, because the kidneys remove excess magnesium.[1]
- High intakes and digestive effects. High doses from supplements or medicines often cause diarrhea, nausea and abdominal cramping. The adult upper limit for supplemental magnesium is 350 mg/day; very large doses from laxatives or antacids (typically over 5,000 mg/day) have caused toxicity.[1]
- Pregnancy and breastfeeding. The RDA is 350–400 mg/day in pregnancy and 310–360 mg/day during lactation (all sources), and the 350 mg/day upper limit for supplemental magnesium still applies.[1]
- Children. Upper limits for supplemental magnesium are lower: 65 mg/day at ages 1–3 and 110 mg/day at ages 4–8.[1]
The evidence, graded
Pulled from our monograph evidence tables. Grades follow our evidence-grading policy.
- Grade CImprovedInsomnia severityInsomnia Severity Index fell 3.9 points versus 2.3 with placebo (p = 0.049); a small effect (Cohen's d = 0.2). No differences in other psychological outcomes.
- Grade CImprovedTime to fall asleep (older adults)Sleep onset latency was 17.4 minutes shorter than placebo; total sleep time rose 16 minutes but not significantly. Trials were at moderate-to-high risk of bias; evidence quality low to very low.
- Grade AImprovedBlood pressureSystolic blood pressure fell by 2.00 mm Hg and diastolic by 1.78 mm Hg versus placebo, with a 0.05 mmol/L rise in serum magnesium. A small average effect.
- Grade CNo effectArterial stiffness and blood pressureCitrate did not change carotid-femoral pulse wave velocity or blood pressure versus placebo. It raised plasma and urinary magnesium, with a larger urinary rise than oxide or sulfate.
First, the label math
Magnesium is always bound to something. Glycinate binds it to glycine; citrate to citric acid. NIH notes that US Supplement Facts panels declare elemental magnesium, the amount of magnesium itself, not the weight of the whole compound [1].
Glycinate is about 14.1% magnesium by weight and citrate about 16.2% [2]. So a capsule holding 700 mg of magnesium glycinate carries about 99 mg of magnesium [1][2]. Front-of-pack claims sometimes quote the compound weight instead. Our magnesium monograph has an elemental converter for every common form.
Citrate: well absorbed, and yes, the bathroom thing
Citrate dissolves well. In short studies it was more bioavailable than magnesium oxide by urinary magnesium [3], and in a 60-day randomized trial of 46 people it gave the highest serum magnesium of the preparations compared [4].
The trade-off is the gut. In a 12-week trial using 600 mg/day, 18.6% of participants reported diarrhea [7]. NIH notes that high supplement doses commonly cause diarrhea, nausea and cramping [1].
Glycinate: gentle, with a small sleep signal
The main absorption study is small: 12 people who had part of their small intestine removed [5]. Overall absorption of a 100 mg dose was similar to oxide (23.5% vs 22.8%), but in the 4 with the poorest oxide absorption, glycinate did better (23.5% vs 11.8%), and all 12 tolerated it better than oxide [5].
For sleep, a 2025 randomized trial gave 250 mg/day of elemental magnesium as bisglycinate or placebo to 155 healthy adults reporting poor sleep [6]. After 4 weeks, insomnia scores fell 3.9 points versus 2.3 with placebo, a small effect (p = 0.049) [6]. Separately, a meta-analysis of 3 trials in older adults with insomnia found people fell asleep 17.4 minutes faster with magnesium, on low-quality evidence [8].
Which one fits you
Neither form has a strong outcome trial behind it. Across all forms, magnesium lowered blood pressure by about 2 mm Hg in a meta-analysis of 34 trials [9]. Read the deeper form pages for glycinate and citrate, and see how much magnesium is too much.
- Want the gentlest option, often at night: glycinate, which was better tolerated than oxide in its small trial [5].
- Want better absorption on a budget and do not mind looser stools: citrate [4][7].
- Take antibiotics like tetracyclines or quinolones, or bisphosphonates: NIH advises spacing them apart from magnesium [1].
- Have kidney problems: talk to your clinician first, because the kidneys clear excess magnesium [1].
Quick answers
Is magnesium glycinate better for sleep than citrate?
Only glycinate has a sleep trial among these two: a small 4-week effect on insomnia scores in 155 poor sleepers [6]. No trial compared the two forms for sleep.
Keep reading
Full monographs
Related articles
- How Much Magnesium Is Too Much? The 350 mg Rule, the Label Trap and Who Should Be Careful
- 400 IU of Vitamin E Is Either 268 mg or 180 mg. The "d" or "dl" on the Label Decides
- Ashwagandha for Stress and Sleep: What the Trials Found, and Why the Results Vary So Much
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Stacks that use it
Browse the full Supplement & Nutrient Encyclopedia or all supplement articles.
References
- [1]Magnesium: Fact Sheet for Health Professionals (updated January 6, 2026). NIH Office of Dietary Supplements, 2026.
- [2]Magnesium glycinate (CID 84645): C4H8MgN2O4, MW 172.42. PubChem, NIH, 2026.
- [3]Magnesium bioavailability from magnesium citrate and magnesium oxide. J Am Coll Nutr, 1990.
- [4]Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnes Res, 2003.
- [5]Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. JPEN J Parenter Enteral Nutr, 1994.
- [6]Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nat Sci Sleep, 2025.
- [7]Prophylaxis of migraine with oral magnesium: results from a prospective, multi-center, placebo-controlled and double-blind randomized study. Cephalalgia, 1996.
- [8]Oral magnesium supplementation for insomnia in older adults: a Systematic Review & Meta-Analysis. BMC Complement Med Ther, 2021.
- [9]Effects of Magnesium Supplementation on Blood Pressure: A Meta-Analysis of Randomized Double-Blind Placebo-Controlled Trials. Hypertension, 2016.