Thorne Glycine Review
#4 of 8 · Best tested / best capsules✓ Label verified · Supplement Facts read Sep 7, 2026Real retailer photo, cut out. Label unedited.
Buy it. The best-tested glycine capsule — 1 g caps mean the 3 g dose is three, not six. Third-party certified, trusted by 100+ pro sports teams, plain glycine with a clean minimal-excipient profile — the strongest testing pedigree on the list, in a 1 g capsule so the studied 3 g dose is three caps.
Several times the powder cost per gramHigher per 3 g dose (3 × 1 g capsules)
Why It Scores 8.6 — And The Label Line Behind Each Number
Purity & form
25% of scorePlain free-form glycine with a clean, minimal excipient profile — the highest purity score on the list. Only the necessary capsule excipients are present, and nothing disqualifying: no magnesium carrier, no NAC, no 'complex.' Thorne's clean-label discipline is a genuine strength, edging out even the powders on this axis.
- Form
- Plain glycine capsules (1 g each)
- Excipients
- Clean, minimal profile — plain free-form glycine
- Diet
- Gluten-, dairy- and soy-free per listing
Third-party testing
25% of scoreThe best on the list. Thorne is third-party certified and is a brand clinicians and more than 100 professional and Olympic teams rely on, with a QC reputation among the strongest in the industry. For a commodity amino acid, this is the verification you would actually pay a premium for — it tops the powders' per-batch testing and dwarfs budget capsules' in-house claims.
- Testing
- Third-party certified; trusted by 100+ pro sports teams
Dose accuracy (3 g)
20% of scoreStrong for a capsule: at 1 g per capsule, the studied 3 g dose is three caps — half the count a 500 mg brand demands. It trails the scooped powders only because three capsules is still more friction than a single scoop, but among capsules this is the clean, practical way to hit the dose.
- Per serving
- 3 g = 3 capsules (label suggests 2 caps, 1-3× daily)
Taste & mixability
15% of scoreScored neutral-to-good, as capsules are throughout this ranking. A capsule avoids taste entirely, which suits people who do not want to mix anything — but it also forfeits glycine's naturally sweet, pleasant-in-water quality, which is a genuine upside of the powders. Neither better nor worse in the abstract, just a different trade.
Value (per 3 g dose)
15% of scoreThe weakest axis, by design. Thorne costs several times more per gram than bulk glycine powder — you are paying for capsule convenience and the best testing pedigree, not a better molecule. Among capsules it is a premium option; the budget capsule (Double Wood, #6) undercuts it on cost. Fair value for what it is, but not a value play.
- Bottle
- 250 capsules (125 × 2-cap servings)
- Value
- Several times the powder cost per gram (capsule premium)
- More Specs
- Convenience
- Travel-friendly — no scooping or mixing
Label verified. Every figure read from the Supplement Facts photo, Sep 7, 2026.
Marketing Claims Vs. Reality
Plain glycine, 1 g per capsule.
The listing describes glycine capsules at 1 g each with a clean excipient profile. This is the free-form glycine this ranking requires, and the 1 g cap is the honest reason the 3 g dose is three capsules rather than six — the claim holds as stated.
Third-party certified; trusted by 100+ professional sports teams.
Thorne's third-party certification and its adoption by clinicians and 100+ professional and Olympic teams are well documented and central to its reputation. This is the strongest, most credible testing pedigree on the list — the claim is accurate.
Gluten-, dairy- and soy-free with a clean minimal excipient profile.
The product overview states a gluten-, dairy- and soy-free formula with minimal excipients, consistent with Thorne's clean-label discipline. Accurate, and a point in the product's favor for sensitive users.
Supports relaxation and healthy sleep at the glycine dose.
Directionally supported by the human evidence on glycine — Yamadera 2007 and Bannai 2012 — but that evidence is moderate, drawn from a few small studies mostly from one lab, and describes glycine generally rather than this product. Thorne's listing also emphasizes relaxation and muscle function; the sleep positioning is a reasonable category claim, not a proven product-specific outcome.
What Our Test Actually Found
The 1 g capsule is what makes this the practical capsule pick
Most capsule glycine ships at 500 mg, which turns the studied 3 g dose into six capsules a night — enough friction that people quietly stop. Thorne's 1 g capsule cuts that to three, which is the difference between a capsule you will actually keep taking and one you will not. Combined with the best testing pedigree on the list, that dose-per-capsule advantage is the core reason Thorne is the capsule to beat, even before you weigh the brand's reputation.
You are paying for verification, not a better molecule
Glycine is chemically identical everywhere, so Thorne's premium buys two things: convenience and the most credible testing on the list. Third-party certification and adoption by clinicians and 100+ pro teams is exactly the assurance worth paying for on a supplement you take nightly. But it is honest to be clear that the glycine itself is no more potent than a bulk powder's — if verification and convenience are not your priorities, you are overpaying versus a powder.
The capsule format costs you glycine's nicest quality
One underrated upside of glycine is that it is naturally sweet, so a powder is genuinely pleasant stirred into water or tea — no flavoring needed. A capsule sidesteps taste entirely, which some people prefer, but it does forfeit that pleasant-drink experience. If you like the idea of a small sweet nightcap you actually enjoy, a powder is better; if you would rather swallow and be done, the capsule is the point.
Same gentle effect, same honest caveat
The best-tested capsule is still just glycine: a gentle aid backed by moderate evidence from a few small studies. About 3 g before bed improved subjective sleep quality and shortened polysomnographic sleep latency (Yamadera 2007), and most reliably reduced next-day fatigue after a short night (Bannai 2012). Take three caps nightly for one to two weeks before judging, and stack it with a cool room and consistent sleep timing. Thorne is the best capsule tool for the job — it is still a small, well-tolerated edge, not a cure.
Full analysis: all pros & cons (8), buy if / skip if
- Best-in-class testing pedigree — third-party certified, clinician- and pro-team-trusted
- 1 g per capsule means the 3 g dose is three caps, not six
- Plain glycine with a clean, minimal excipient profile
- Gluten-, dairy- and soy-free — good for sensitive users
- Convenient and travel-friendly — no scooping or mixing
- Costs several times more per gram than any of the powders
- Capsules sidestep glycine's naturally sweet, mix-in-water upside
- Double Wood (#6) undercuts it on price for the same 1 g-capsule format
- You want capsules over powder and the most trusted testing pedigree available
- You want the 3 g dose in three caps, not the six a 500 mg brand needs
- You travel or want grab-and-go convenience with no scooping or mixing
- You value a clinician- and pro-team-trusted brand for a supplement you take nightly
- Cost per gram is your priority — powders (#1 to #3) are several times cheaper
- You want glycine's naturally-sweet, mix-in-water experience — that is a powder
- You want the cheapest capsule route — Double Wood (#6) is the value 1 g cap
Third-party certified, trusted by 100+ pro sports teams, plain glycine with a clean minimal-excipient profile — the strongest testing pedigree on the list, in a 1 g capsule so the studied 3 g dose is three caps. The trade-offs are the format's: several times the powder cost per gram, and no naturally-sweet mixable upside. Buy it for capsules and verification; a powder wins on cost.
If you want capsules instead of powder, Thorne Glycine is the one to beat. Its testing pedigree is the best on this list — third-party certified, and a brand clinicians and more than 100 professional sports teams actually rely on — and crucially it is a 1 g capsule, so hitting the studied 3 g dose takes three caps rather than the six that 500 mg brands demand. The glycine is plain, with a clean, minimal excipient profile. The trade-offs are inherent to the format, not to Thorne. You pay several times the powder cost per gram, and a capsule sidesteps glycine's naturally sweet, pleasant-in-water quality entirely. That is why it sits below the three powders overall despite topping them on purity and testing. For travel, convenience, or maximum verification assurance, it is the obvious capsule pick; for pure cost-efficiency at home, a powder still wins. Here is the full breakdown.
The capsule to beat — buy it for convenience and the best testing; a powder wins on cost.
Thorne Glycine is the right call for a buyer who wants capsules over powder and cares about verification. The testing pedigree is the best on the list — third-party certified, trusted by clinicians and 100+ pro teams — and the 1 g capsule keeps the studied 3 g dose to three caps rather than six. The glycine is plain, with a clean, minimal excipient profile. The trade-offs are inherent to capsules, not to Thorne: you pay several times the powder price per gram, and you forfeit glycine's naturally sweet, pleasant-in-water quality. That is why it sits below the powders overall despite topping them on purity and testing. For travel, convenience, or maximum testing assurance it is an easy choice; if cost per gram is your priority, a powder (#1 to #3) wins outright, and if you want the cheapest capsule specifically, Double Wood (#6) is the value pick. Take three caps, 30 to 60 minutes before bed, give it one to two weeks, and stack it with good sleep timing and a cool room.
If This Doesn’t Fit — Try These
03BulkSupplements Glycine Powder
For the lowest cost per gram with real per-batch testing, this is the one to buy.
06Double Wood Glycine
If you've decided on capsules and value is your priority, Double Wood is the answer.
05Pure Encapsulations Glycine
Pure Encapsulations is the pick for one specific buyer: someone who wants the cleanest, most allergen-free label possible and is willing to pay for it.
Quick Answers
How many Thorne capsules make the 3 g sleep dose?
Three. Thorne portions 1 g of glycine per capsule, so the studied 3 g pre-bed dose is three capsules — a real advantage over the 500 mg brands, which need six. The label suggests 2 capsules taken 1 to 3 times daily; for the sleep dose specifically, take three capsules 30 to 60 minutes before bed. That 1 g cap is exactly why Thorne is the most practical capsule for hitting the studied dose.
Why is Thorne considered the best-tested option?
Thorne is third-party certified and is a brand clinicians and more than 100 professional and Olympic sports teams actually rely on, with a QC reputation among the strongest in supplements. For a commodity ingredient like glycine, that verification is the main thing you would pay a premium for — and Thorne's is the most credible testing pedigree on this list, ahead of the powders' per-batch testing and well ahead of budget capsules.
Is it worth paying more than a powder?
Only if you want capsules. The glycine is chemically identical to the powders, so you are paying for convenience and Thorne's testing pedigree, not a better molecule. Capsules cost several times more per gram than bulk glycine powder, and they sidestep glycine's naturally sweet, pleasant-in-water quality. For travel, grab-and-go, or maximum testing assurance, Thorne is an easy call; for the lowest cost at home, a powder (#1 to #3) wins.
Is it plain glycine or a blend?
Plain glycine, with a clean, minimal excipient profile. The sleep evidence is for glycine by itself, so anything labeled 'glycine complex,' NAC+glycine, or magnesium glycinate was disqualified from this ranking. Thorne's capsule is free-form glycine plus only the minimal excipients any capsule needs — exactly the plain glycine you want for the 3 g dose, just in capsule form.
Sources & Further Reading
3 sources — studies link to PubMed, product specs to the manufacturer
- [1] Bannai 2012 PMID 22529837 — The effects of glycine on subjective daytime performance in partially sleep-restricted healthy volunteers. In healthy volunteers whose sleep was restricted for three nights, 3 g of glycine before bed significantly reduced subjective daytime fatigue and sleepiness and improved reaction-time performance versus placebo. The best-replicated glycine sleep finding — but a small study, and the authors are affiliated with a glycine manufacturer (noted for transparency).
- [2] Kawai 2015 PMID 25533534 — The sleep-promoting and hypothermic effects of glycine are mediated by NMDA receptors in the suprachiasmatic nucleus. Mechanistic study in rats: oral glycine promoted sleep and lowered core body temperature by acting on NMDA receptors in the suprachiasmatic nucleus (the master circadian clock), increasing skin blood flow and heat loss. Provides the leading biological explanation for glycine's sleep effect — but it is an animal study, so extrapolation to humans is indirect.
- [3] Yamadera 2007 — Glycine ingestion improves subjective sleep quality in human volunteers, correlating with polysomnographic changes. In volunteers with unsatisfactory sleep, 3 g of glycine before bed improved subjective sleep quality and, on polysomnography, shortened latency to sleep onset and to slow-wave sleep. The canonical human glycine-sleep study and the source of the 3 g dose — but small (~11 subjects) and published in a journal PubMed does not index, so no PMID exists. Cited honestly without a fabricated identifier.
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