Thorne Magnesium Glycinate
Best general-purpose magnesium supplement for sleep, muscle relaxation, and recovery. NSF Certified for Sport, 120 mg elemental magnesium per capsule, 90 servings for ~$26. Take 1-2 capsules 30-60 minutes before bed.
Check Price on Amazon →| Form | Bioavailability | Best For | Notable Issue |
|---|---|---|---|
| Magnesium Glycinate (bisglycinate) | High | Sleep, anxiety, muscle relaxation | Most expensive per mg elemental Mg |
| Magnesium Citrate | High | Constipation, general repletion | Laxative effect at higher doses |
| Magnesium L-Threonate (Magtein) | Crosses blood-brain barrier | Cognitive function, memory | Expensive, limited human evidence |
| Magnesium Oxide | Low (~4%) | Cheap repletion, occasional constipation | Poor absorption, GI upset |
| Brand | Form | Elemental Mg / Cap | Servings | Price | Cost / Cap |
|---|---|---|---|---|---|
| Thorne Magnesium Glycinate | Bisglycinate | 120 mg | 90 | $26 | $0.29 |
| Pure Encapsulations Magnesium (Glycinate) | Bisglycinate | 120 mg | 90 | ~$30 | $0.33 |
| Doctor's Best High Absorption Magnesium | Lysinate Glycinate Chelate | 100 mg | 120 | ~$24 | $0.20 |
| Nature Made Magnesium Glycinate | Bisglycinate | 200 mg | 60 | ~$13 | $0.22 |
Thorne Magnesium Glycinate has become the default recommendation across the clinical-nutrition crowd, and search interest has grown over 12× year-over-year as the brand-tail query has gone mainstream. It’s a 120 mg elemental magnesium capsule using the glycinate chelate (also called bisglycinate) — the form best-studied for sleep, muscle relaxation, and tolerability. This is a focused review of the capsule version: who it’s for, what the evidence actually says, where it fits among other magnesium forms, and the honest case for and against it.
To ground the claims, I pulled the 2025 randomized controlled trial on magnesium bisglycinate from Nature and Science of Sleep, NHANES data on US adult magnesium intake, Thorne’s own 28-day consumer study (clearly labelled as company-funded below), and the product’s actual current price across Thorne, Amazon, Mayo Clinic Store, and iHerb. Where Thorne’s marketing claims go beyond what the peer-reviewed literature supports, I’ll say so.
Health Disclaimer: This page is for educational purposes only and is not medical advice. Magnesium supplementation can interact with prescription medications (notably some antibiotics, bisphosphonates, and proton pump inhibitors) and is not appropriate for people with kidney disease or severely impaired renal function. Talk to your doctor before starting any magnesium supplement, especially if you take prescription medication or have a diagnosed medical condition.
What Is Thorne Magnesium Glycinate?
Thorne Magnesium Glycinate is a dietary supplement containing 120 mg of elemental magnesium per capsule, delivered as magnesium bisglycinate — magnesium bonded to two glycine amino acid molecules. The current Amazon listing (ASIN: B0F5XYHRPV) is a 90-capsule bottle at $26, identical pricing to Thorne’s own store, Mayo Clinic’s online store, and Target. The “bisglycinate” name is technically more accurate than “glycinate” (two glycine molecules attached, not one), but both refer to the same compound — Thorne and most other brands use the names interchangeably.
Thorne is a US-based supplement manufacturer founded in 1984. They’re best known in the clinical world for partnering with the Mayo Clinic on research and for being one of the few brands with extensive third-party certifications — including NSF Certified for Sport, which independently tests every batch for over 270 banned substances. That certification is the reason this product appears in pro athlete supplement stacks; it’s also why the Mayo Clinic Store sells it directly.
The Evidence: Does Magnesium Glycinate Actually Work?
For sleep
The strongest recent evidence comes from a 2025 randomized, double-blind, placebo-controlled trial published in Nature and Science of Sleep. Researchers gave 155 adults aged 18–65 with self-reported poor sleep quality either 250 mg of elemental magnesium as bisglycinate or a placebo, every night for four weeks. The magnesium group showed a statistically significant reduction in Insomnia Severity Index (ISI) scores compared to placebo. The effect size was modest — this isn’t a sleeping pill — but it was real. Exploratory analysis showed the largest improvements in participants whose baseline dietary magnesium intake was lowest (suggesting it works best on people who are actually deficient, which is roughly half the US adult population — more on that in a moment). [Citation: Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep — PMC12412596 (2025)]
For muscle relaxation and recovery
Glycine itself — the amino acid bonded to magnesium in this product — is an inhibitory neurotransmitter and a recognized muscle relaxant. Magnesium plays a role in over 300 enzymatic reactions including muscle contraction and relaxation, and low magnesium status is associated with muscle cramps and restless legs. The glycinate form is generally preferred for these uses because it doesn’t cause the laxative effect that magnesium citrate or oxide can.
For deficiency correction
This is where the case is strongest. According to NHANES dietary data, roughly 50% of US adults consume less magnesium than the Estimated Average Requirement. The mean intake is about 304 mg/day in men (RDA: 420 mg) and 263 mg/day in women (RDA: 320 mg). The highest deficiency rates are in adolescent males and adults over 75. Symptoms of subclinical deficiency can include muscle cramps, fatigue, irritability, and poor sleep — exactly the symptoms a supplement like this might address by correcting an underlying shortfall rather than producing a pharmacologic effect.
Thorne’s own consumer study (company-funded)
Thorne published a 28-day consumer study on this product in April 2026. They report 91% of participants experienced improved sleep quality, 94% felt calmer in stressful situations, and 84% noticed improvements in stress levels and mood. Important transparency note: this is a company-funded consumer study, not a peer-reviewed randomized controlled trial. There’s no placebo arm, no blinding, and no comparison group. Read it as marketing-quality evidence, not clinical evidence — but it’s useful for understanding what subjective experience users report. [Source: Thorne — 28-day consumer study (April 2026)]
Magnesium Glycinate vs Citrate vs Oxide vs L-Threonate
Magnesium isn’t just one ingredient — there are over a dozen common chelate and salt forms, and they behave differently. Here’s how the four most common stack up:
Glycinate vs Citrate: Both have similarly good bioavailability. The deciding factor is the laxative effect — citrate pulls water into the gut osmotically, which is great if you want it (constipation) and terrible if you don’t (everyone else). Glycinate is absorbed across the small intestine without that osmotic pull, so it stays in your system instead of running through it.
Glycinate vs L-Threonate: L-Threonate (sold as Magtein) is the only magnesium form proven to cross the blood-brain barrier in animal studies, and is marketed for cognitive function. Human evidence is thinner than for glycinate. L-Threonate is also 2-3× more expensive per dose. For sleep and muscle relaxation, glycinate is the right call; for daytime cognitive support, L-Threonate may add something glycinate can’t.
Glycinate vs Oxide: Oxide is what’s in nearly every $5 drugstore magnesium supplement. Absorption is poor (estimates around 4%), and the unabsorbed magnesium can cause GI upset. The high elemental content per pill is meaningless if your body can’t access it. Avoid for sleep and recovery use.
What Real Users Say
Across 367 reviews on Thorne.com, 1,037 reviews on the Mayo Clinic Store listing, and the Amazon listing, the consistent themes:
- Faster sleep onset — most commonly reported benefit, usually within 3-7 days of starting
- Reduced muscle tension at the end of the day, particularly for desk workers and people who train hard
- Calmer baseline — reduced stress response (subjective, not measured)
- No GI side effects — the main differentiator from cheaper citrate or oxide products
The most common complaint, reflected in some Walmart reviews: confusion about per-capsule dose. The bottle is labelled 120 mg per capsule, not 300 mg. The serving size on the supplement facts panel is one capsule, but the clinical dose used in the 2025 RCT was 250 mg — so most users will want two capsules per night to hit the studied dose. Read the label and plan accordingly.
Dosage and Timing
Based on the published clinical evidence and Thorne’s own guidance:
- Starting dose: 1 capsule (120 mg) about 30-60 minutes before bed. Hold for 5-7 days to see if you tolerate it well.
- Clinical dose: 2 capsules (240 mg) — close to the 250 mg used in the 2025 RCT. Most adults who are deficient (~50% of the US population by NHANES) will need this dose to see effects.
- Upper limit: The Tolerable Upper Intake Level for supplemental magnesium (not dietary) is 350 mg/day for adults per the Institute of Medicine, due to risk of GI side effects at higher doses. Glycinate is gentler than other forms but stay under 350 mg/day from supplements unless directed by a clinician.
- Timing: Before bed for sleep benefits. With or without food — glycinate doesn’t require food for absorption.
Who Should NOT Take This
- Anyone with kidney disease or impaired renal function. The kidneys clear excess magnesium; if they can’t, magnesium can accumulate to dangerous levels. Hard contraindication — talk to your nephrologist.
- Anyone taking certain prescription medications. Magnesium can reduce absorption of some antibiotics (tetracyclines, fluoroquinolones), bisphosphonates (osteoporosis drugs), and levothyroxine. Generally fine to take separated by 2-4 hours, but check with your pharmacist.
- People on proton pump inhibitors (omeprazole, esomeprazole) long-term. Long-term PPI use can lower magnesium levels — supplementing may help, but you should be monitoring labs.
- Pregnant or breastfeeding people without a doctor’s clearance. The RDA is slightly different, and supplements during pregnancy should be cleared with your OB.
Comparison: Thorne Magnesium Glycinate vs Capsule Alternatives
Bottom line on alternatives: Doctor’s Best is the value pick if NSF certification doesn’t matter to you (still a well-absorbed lysinate/glycinate chelate). Nature Made is the true budget play — USP-verified, 200 mg elemental per capsule, and by far the cheapest per mg of elemental magnesium in this table. Pure Encapsulations is essentially Thorne with different branding (both are clinical-grade chelates). Thorne’s premium over the field is the NSF Certified for Sport stamp — meaningful if you compete in tested sports, less meaningful if you just want magnesium for sleep.
How We Picked
Every product in the comparison table above was checked against the following bar before it earned a row:
- PA API verification. Each ASIN was pulled through Amazon’s Product Advertising API immediately before publish. Titles, current prices, and stock status were confirmed live — no guessed ASINs, no stale pricing carried forward from prior drafts.
- Third-party certification check. NSF Certified for Sport and USP Verified marks were re-checked against the certifier’s public directory, not the manufacturer’s marketing page. Uncertified products are still listed but flagged as such.
- Chelate form matches the label. Bisglycinate, glycinate lysinate chelate, and citrate were confirmed on the current supplement facts panel — not inferred from a product name.
- No paid placement. No manufacturer paid to appear in this comparison or in the final CTA. Amazon affiliate links pay us a small commission if you buy through them; this does not change which product we recommend, and the “Budget Pick” in the final CTA is deliberately a different brand than the “Premium Pick” so the recommendation is form-first, not commission-first.
Who Should Skip Thorne Magnesium Glycinate Entirely
Beyond the medical contraindications above (kidney disease, specific drug interactions), there are three buyer profiles who should genuinely look elsewhere — not because Thorne is bad, but because it’s not the right fit for what they actually need:
- Anyone with kidney disease or on multiple interacting prescriptions. This is the hardest of the three. If you have reduced renal function, magnesium can accumulate to dangerous levels because the kidneys are what clear the excess. Same goes if you’re on bisphosphonates (osteoporosis), tetracyclines or fluoroquinolones (antibiotics), or certain blood-pressure meds — magnesium chelates or delays absorption of all of these, and the fix is either spacing (2–4 hours apart) or picking a different intervention. In either case, this is a “talk to your prescribing physician first” situation, not a supplement-aisle decision.
- Cognitive-function seekers. If your goal is memory, focus, or age-related cognitive support, magnesium glycinate is the wrong form. The blood-brain-barrier work has been done on magnesium L-threonate (Magtein), not glycinate. Glycinate is the sleep-and-muscle-relaxation form; L-threonate is the daytime-brain form. Buying Thorne Glycinate for cognitive benefit is buying the wrong tool.
- Budget-constrained maintenance dosers. Thorne is premium-priced because of NSF Certified for Sport batch testing — worthwhile if you compete in a tested sport, largely aesthetic if you don’t. For pure repletion at maintenance doses (200–300 mg/day), Nature Made Magnesium Glycinate (USP Verified, 200 mg/cap, ~$13) and NOW Foods Magnesium Glycinate deliver equivalent elemental magnesium in the same chelate form at roughly one-third the cost per mg. If the price gap actually matters to your monthly budget, buy the cheaper USP-verified option and take the savings.
My Verdict
If you’re shopping for a magnesium supplement specifically for sleep, muscle relaxation, or general repletion, Thorne Magnesium Glycinate is the right buy for most people. It’s the form with the best clinical evidence for sleep (validated in a 2025 RCT), the lowest GI side effect profile, and one of the few products with NSF Certified for Sport batch testing. At $0.29 per capsule and $26 for a 45-night supply (at the 2-capsule clinical dose), it’s expensive relative to drugstore oxide but reasonable relative to other clinical-grade chelates.
Buy this if: you have trouble falling asleep, you train hard and want recovery support, you compete in NSF-tested sports, or you suspect you’re in the ~50% of US adults with subclinical magnesium deficiency.
Don’t buy this if: you’re looking for cognitive enhancement (consider magnesium L-threonate / Magtein instead), you have kidney disease, or your budget is tight (Nature Made Magnesium Glycinate at ~$13 for 60 caps of 200 mg elemental — USP Verified — is the true budget play, and Doctor’s Best at ~$0.20 per cap covers the middle if you want a lysinate-glycinate chelate without paying the NSF premium).
Frequently Asked Questions
Is Thorne Magnesium Glycinate the same as bisglycinate?
Yes. “Bisglycinate” is the more precise chemical name (two glycine molecules bonded to one magnesium ion), but the supplement industry uses “glycinate” and “bisglycinate” interchangeably. Thorne actually sells two distinct products: their Magnesium Glycinate (capsules, $26) and Magnesium Bisglycinate (powder, $52) — different SKUs, same underlying chelate.
How long does it take to work?
Most users report improvements in sleep onset and quality within 3-7 days. The 2025 RCT measured outcomes at 4 weeks, so give it a full month before deciding whether it’s working. If you have nothing to show after 4-6 weeks of consistent use at 240 mg/night, magnesium probably isn’t your bottleneck.
Can I take it with melatonin or other sleep supplements?
Generally yes — magnesium and melatonin work via different mechanisms and are commonly stacked. If you’re combining multiple sleep supplements, start with magnesium alone for 2-4 weeks to see what it does on its own before stacking.
Why is the Mayo Clinic Store selling it?
Mayo Clinic has a longstanding research partnership with Thorne. The Mayo Clinic Store carries Thorne products at the same price as Thorne.com because Mayo trusts the third-party testing and the formulation quality. This isn’t a paid endorsement — it’s a clinical-supply relationship.
What does “NSF Certified for Sport” mean?
NSF International independently tests every batch of the certified product for over 270 substances banned by major sports organizations (WADA, NFL, MLB, NHL, etc.). The certification is meaningful because supplement adulteration is a real problem — about 12-15% of supplements tested off-the-shelf contain undeclared ingredients. NSF for Sport is the strictest of the third-party certifications.
How does it compare to Magtein (L-Threonate) for sleep?
For falling asleep faster and reducing muscle tension, glycinate has better evidence. For cognitive function during the day, L-Threonate has the unique brain-penetration property. Some people stack them — glycinate at night, L-Threonate in the morning. For just sleep, start with glycinate.
Will it cause loose stools?
Glycinate is the most GI-friendly magnesium form. If you’ve had loose stools from magnesium citrate or oxide, glycinate almost certainly won’t cause them. If you do experience GI symptoms, drop to one capsule and reassess.
Honest Limitations of This Guide
A few things this review does not establish, that a marketing page would happily pretend it does:
- We haven’t personally used Thorne through a full repletion cycle. The NHANES-referenced deficiency case implies most users are correcting a subclinical shortfall, and correction typically takes 8–12 weeks of consistent daily dosing before serum and intracellular magnesium normalize. Our verdict is grounded in the published RCT evidence and in the aggregated user-review base, not in a first-person 12-week repletion diary.
- NSF Certified for Sport verifies purity, not superior clinical effect. The certification confirms that the batch matches the label and contains no banned substances or undeclared contaminants. It does not verify that Thorne’s glycinate outperforms a USP-verified competitor’s glycinate on sleep or muscle-relaxation endpoints. If someone tells you NSF makes the product “work better,” they’re conflating quality assurance with efficacy.
- ”Glycinate has superior bioavailability” is a manufacturer-favored claim. The chelate story is mechanistically plausible and the tolerability advantage over citrate and oxide is real and consistent across the literature. But rigorous head-to-head human pharmacokinetic studies comparing glycinate vs citrate vs threonate at matched elemental doses are thinner than the marketing suggests. We treat the tolerability edge (fewer GI side effects) as well-established and the raw absorption edge as directionally supported but not settled.
- The 2025 RCT effect size was modest (Cohen’s d ≈ 0.2). Statistically significant is not the same as clinically dramatic. Magnesium is a real intervention for sleep, but it isn’t a sedative and shouldn’t be sold as one. Expect a nudge, not a knockout.
Final Thoughts
Magnesium glycinate is one of the few supplements with both real clinical evidence (the 2025 Insomnia Severity Index RCT) and a clear deficiency-correction rationale (NHANES showing half of US adults under-consume it). Thorne’s version is the premium-tier pick — clinical-grade chelate, NSF Certified for Sport, third-party tested, sold through Mayo Clinic. The competition is real (Doctor’s Best at half the price, Pure Encapsulations as a nearly identical alternative), but Thorne is the right default if you want one supplement that does sleep, muscle relaxation, and stress in one capsule and you don’t want to think about it again.
If you build a broader sleep stack, pair this with our mouth tape and sleep mask picks. For the broader magnesium-form comparison, see our best magnesium guide.
Sources and Citations
- Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial — Nature and Science of Sleep, 2025. n=155 adults, 250 mg/d for 4 weeks, primary outcome Insomnia Severity Index.
- Thorne 28-Day Consumer Study (April 2026) — company-funded, no placebo arm; cited for subjective user experience data only.
- Thorne — Research Extracts: Nighttime Magnesium Glycinate and Sleep Quality (March 2026)
- Dietary Magnesium Intake in a National Sample of U.S. Adults — NHANES analysis, ~50% of US adults below EAR.
- Magnesium: Health Effects, Deficiency Burden, and Future Public Health Directions — Nutrients, 2025 review.
- Subclinical magnesium deficiency: a principal driver of cardiovascular disease and a public health crisis — DiNicolantonio et al.
- Mayo Clinic Store — Thorne Magnesium Glycinate product listing
Last updated: July 4, 2026. Pricing and ASINs re-verified via Amazon PA API on publish day (Thorne $26 / 90 caps; Doctor’s Best $23.99 / 120 caps). Clinical evidence sourced from Schuster et al. 2025 (Nature and Science of Sleep, n=155, PMC12412596) and NHANES dietary intake data. As an Amazon Associate, DeskFitPro earns from qualifying purchases.
