Magnesium

• −2.00 mmHgsystolic · 95% CI 0.43-3.58
• −1.78 mmHgdiastolic · 95% CI 0.73-2.82
• 34 trialsn = 2028

A meta-analysis of 34 placebo-controlled trials found that magnesium supplementation produced a small but statistically significant reduction in both systolic and diastolic blood pressure in studied adults, accompanied by a measurable rise in serum magnesium. The effect size is modest (roughly 2 mmHg), consistent with a mild blood-pressure-support role rather than a substitute for antihypertensive therapy.

Reported effect: 34 trials, 2028 participants; median dose 368 mg/d for 3 months reduced systolic BP by 2.00 mmHg (95% CI 0.43-3.58) and diastolic BP by 1.78 mmHg (95% CI 0.73-2.82)

“34 trials involving 2028 participants were eligible for this meta-analysis ... Mg supplementation at a median dose of 368 mg/d for a median duration of 3 months significantly reduced systolic BP by 2.00 mm Hg (95% confidence interval, 0.43-3.58) and diastolic BP by 1.78 mm Hg (95% confidence interval, 0.73-2.82)”

Source: PMID 27402922 · Zhang et al. 2016 · Hypertension

• −17.4 minsleep onset · p=0.0006
• +16 mintotal sleep · NS
• 3 RCTsn = 151 older adults

A systematic review and meta-analysis of three RCTs in older adults found magnesium shortened sleep onset latency by about 17 minutes versus placebo, but the gain in total sleep time was not statistically significant. The authors flagged moderate-to-high risk of bias and low-to-very-low quality evidence, so this is a promising but not robustly established finding.

Reported effect: 3 RCTs, 151 older adults; sleep onset latency 17.36 min shorter vs placebo (95% CI -27.27 to -7.44, p=0.0006); total sleep time +16.06 min but statistically insignificant

“Three randomized control trials (RCT) were identified comparing oral magnesium to placebo in 151 older adults in three countries. Pooled analysis showed that post-intervention sleep onset latency time was 17.36 min less after magnesium supplementation compared to placebo (95% CI - 27.27 to - 7.44, p = 0.0006). Total sleep time improved by 16.06 min in the magnesium supplementation group but was statistically insignificant.”

Source: PMID 33865376 · Mah & Pitre 2021 · BMC Complement Med Ther

• OR 0.20oral · migraine frequency
• OR 0.23IV · acute relief 15-45 min
• 21 studiesIV + oral arms

A meta-analysis of 21 trials reported that both intravenous magnesium (for acute attacks) and oral magnesium (for prophylaxis) were associated with significantly lower migraine frequency and intensity, expressed as favorable odds ratios. The abstract reports odds ratios but does not provide confidence intervals, so the precision of these estimates is not extractable here.

Reported effect: 21 studies; IV Mg relieved acute migraine (ORs 0.23, 0.20, 0.25 at 15-45 min, 120 min, 24 h; 948 participants); oral Mg reduced migraine frequency and intensity (ORs 0.20 and 0.27; 789 participants) — no CIs reported in abstract

“A total of 21 studies were included. ... Intravenous magnesium significantly relieved acute migraine within 15 - 45 minutes, 120 minutes, and 24 hours after the initial infusion (Odd ratios [ORs] = 0.23, 0.20, and 0.25, respectively). Oral magnesium significantly alleviated the frequency and intensity of migraine (ORs = 0.20 and 0.27).”

Source: PMID 26752497 · Chiu et al. 2016 · Pain Physician

• SMD −0.40fasting glucose (diabetes)
• SMD −0.352h post-OGTT (at-risk)
• 18 RCTsHOMA-IR trend only

A meta-analysis of 18 RCTs found magnesium significantly lowered fasting plasma glucose in people with diabetes and improved post-load glucose in at-risk groups, but the reduction in insulin resistance (HOMA-IR) reached only trend-level significance with confidence intervals crossing zero. The picture is one of a meaningful glycemic adjunct in specific populations rather than a uniform insulin-sensitizing effect.

Reported effect: 18 RCTs; fasting glucose in diabetes (9 studies, n=336) SMD -0.40 (95% CI -0.80 to -0.00); 2h post-OGTT glucose in at-risk (3 studies) SMD -0.35 (95% CI -0.62 to -0.07); HOMA-IR (5 studies) SMD -0.57 (95% CI -1.17 to 0.03, trend-level, CI crosses zero)

“Mg treatment (n=336) reduced fasting plasma glucose (studies=9; SMD=-0.40; 95% CI: -0.80 to -0.00; I2=77%) ... Mg supplementation significantly improved plasma glucose levels after a 2 h oral glucose tolerance test (three studies; SMD=-0.35; 95% CI: -0.62 to -0.07; I2=0%) ... demonstrated trend level reductions in HOMA-IR (five studies; SMD=-0.57; 95% CI: -1.17 to 0.03; I2=88%)”

Source: PMID 27530471 · Veronese et al. 2016 · Eur J Clin Nutr

• d = 0.91cognitive ability · p=0.003
• n = 4412 weeks · MMFS-01
• Mg L-threonatesingle proprietary trial

A 12-week randomized, double-blind, placebo-controlled trial of MMFS-01 (a magnesium L-threonate formula) in older adults with cognitive impairment found a significant, large improvement in overall cognitive ability versus placebo. This is a single small trial of a specific proprietary formulation, so the result is encouraging but not yet broadly replicated.

Reported effect: n=44 (MMFS-01 n=23, placebo n=21), 12 weeks; overall cognitive ability improved significantly vs placebo (p=0.003; Cohen's d=0.91)

“Subjects were treated with MMFS-01 (n = 23) or placebo (n = 21) for 12 weeks ... overall cognitive ability improved significantly relative to placebo (p = 0.003; Cohen's d = 0.91) ... MMFS-01 treatment nearly restored their impaired executive function”

Source: PMID 26519439 · Liu et al. 2016 · J Alzheimers Dis

• −6.0 ptsPHQ-9 · P<0.001
• −4.5 ptsGAD-7 · P<0.001
• 248 mg/dopen-label · 2 weeks

An open-label randomized clinical trial found that 248 mg/day of elemental magnesium produced a clinically meaningful net improvement in depression (PHQ-9) and anxiety (GAD-7) scores within two weeks. Because the trial was open-label rather than placebo-blinded, the magnitude should be read with that design limitation in mind.

Reported effect: 112 analyzable participants; 248 mg/d elemental magnesium; net PHQ-9 improvement -6.0 points (CI -7.9, -4.2; P<0.001) and GAD-7 improvement -4.5 points (CI -6.6, -2.4; P<0.001); effects within 2 weeks

“112 participants provided analyzable data ... 248 mg of elemental magnesium per day ... net improvement in PHQ-9 scores of -6.0 points (CI -7.9, -4.2; P<0.001) ... net improvement in Generalized Anxiety Disorders-7 scores of -4.5 points (CI -6.6, -2.4; P<0.001) ... Effects were observed within two weeks.”

Source: PMID 28654669 · Tarleton et al. 2017 · PLoS One

• 4/8anxious-sample studies positive
• 18 studiesevidence quality poor
• 0 validatedstress-outcome measures

A systematic review of 18 studies found that a minority of trials reported positive effects of magnesium on subjective anxiety, but the authors judged the overall evidence quality as poor and noted no study used a validated stress-outcome measure. This is an honest signal-without-confirmation finding that calls for well-designed RCTs.

Reported effect: 18 studies; positive anxiety effects in 4/8 anxious samples, 4/7 PMS samples, 1/2 hypertensive samples; authors rate evidence quality as poor

“18 studies were included in the review. Four/eight studies in anxious samples, four/seven studies in PMS samples, and one/two studies in hypertensive samples reported positive effects of Mg on subjective anxiety outcomes. However, the quality of the existing evidence is poor. Well-designed randomised controlled trials are required to further confirm the efficacy of Mg supplementation.”

Source: PMID 28445426 · Boyle, Lawton & Dye 2017 · Nutrients

• 71%responders · +1-8% density
• P<0.02treated rise at 1 yr
• P<0.001controls declined

A two-year controlled trial in postmenopausal osteoporosis found that most magnesium-treated patients gained trabecular bone density while untreated controls lost density significantly. This is a small, dated, non-randomized trial, so it is suggestive supporting evidence rather than definitive proof.

Reported effect: 31 treated postmenopausal patients vs 23 untreated controls; 22 patients (71%) responded with a 1-8% rise in bone density; treated mean increased significantly after 1 year (P<0.02) while controls decreased significantly (P<0.001)

“Thirty-one postmenopausal patients ... Twenty-three symptom-free postmenopausal women [controls] ... Twenty-two patients (71 per cent) responded by a 1-8 per cent rise of bone density. The mean bone density of all treated patients increased significantly after 1 year (P < 0.02) ... in untreated controls, the mean bone density decreased significantly (P < 0.001).”

Source: PMID 8274361 · Stendig-Lindberg et al. 1993 · Magnes Res