Nutricost Glycine Powder is the easygoing value pick and a genuine near-tie with the overall winner. You get 100% plain glycine — non-GMO, gluten-free, no fillers — portioned at 3 g per serving with a measuring scoop actually included in the tub, so you hit the studied sleep dose without measuring by eye. Add independent ISO-accredited lab testing in a GMP-compliant, FDA-registered facility, and a cost per dose within a rounding error of the cheapest bulk bag, and it is a legitimate co-recommendation rather than a consolation pick. It sits at #2 for two small reasons, not one big one. Cost per gram is marginally higher than the largest bulk bags because Nutricost sells mainly in a 1 lb tub rather than a 1 kg bag, and the testing is ISO-accredited but not the per-batch, multi-stage program the #1 pick runs. Neither changes the experience: this is plain glycine, correctly dosed, tidily packaged, cheaply priced. If a scoop-in-a-tub is worth a hair more to you than the absolute lowest price, buy this. Here is the full breakdown.
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Read the complete Glycine guide →100% plain glycine, non-GMO and gluten-free, with no fillers or blend — the free-form glycine the sleep studies used. Nothing disqualifying: no magnesium carrier, no NAC, no vague 'complex.' It scores essentially level with the top powders on purity; the marginal gap is packaging assurance and brand-tier positioning, not the glycine itself.
Independent ISO-accredited laboratory testing in a GMP-compliant, FDA-registered facility. That is genuinely solid verification for a commodity amino acid, and well ahead of untested bulk powders. It scores a step below the #1 pick's per-batch, multi-stage program and Thorne's third-party certification, which is the single reason it does not top this axis.
The serving is portioned at 3 g — the exact studied dose — and a measuring scoop is included in the tub, so you hit it without eyeballing a teaspoon. That included scoop is a real, practical edge over powders that make you measure your own. It sits just behind the #1 pick only on the finest margin of scoop precision.
Glycine's natural sweetness carries here too: the powder dissolves clear in water or tea and tastes faintly sweet with no added flavoring, mixing cleanly with no grit. It scores just a touch under the very top only because a powder still asks you to stir a glass, which capsule users would rather avoid.
Essentially tied with the #1 pick on cost per dose — a few cents per 3 g serving. Glycine is one of the cheapest amino acids made, and Nutricost passes that through at value-brand pricing. The only nuance is that it sells mainly in a 1 lb tub (about 150 servings), so the very largest bulk bags edge it out slightly on cost per gram.
“100% plain glycine, non-GMO and gluten-free.”
The listing describes a plain, non-GMO, gluten-free glycine powder with no added ingredients. This is the free-form glycine the sleep studies used and the form this ranking requires — the claim holds as stated.
“3 g per serving with a measuring scoop included.”
The serving is 3 g — matching the dose used in the human glycine sleep trials (Yamadera 2007; Bannai 2012, PMID 22529837) — and Nutricost includes a scoop in the tub. The dose-accuracy claim is accurate and the included scoop is a real convenience.
“Tested by independent ISO-accredited laboratories.”
Nutricost states independent ISO-accredited lab testing and GMP-compliant, FDA-registered manufacturing. That is appropriate, real verification for a commodity amino acid — stronger than untested bulk powders, a small step below per-batch multi-stage programs.
“Improves sleep at the 3 g 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. A reasonable category claim, not a proven product-specific outcome.
Nutricost and the #1 pick are functionally the same molecule at the same 3 g serving, so the tiebreakers are packaging and price. Nutricost's edge is the measuring scoop in the tub: it portions the studied dose for you, so there is no eyeballing a rounded teaspoon and no guessing. For a supplement whose effect is gentle and easy to miss, taking the exact studied amount every night — effortlessly — is worth the marginal cost. If you want the friendliest possible powder experience without paying capsule prices, this is it.
For a commodity ingredient, verification is what you are really buying, and Nutricost delivers it: independent ISO-accredited lab testing in a GMP-compliant, FDA-registered facility. That is trustworthy and well ahead of anonymous bulk powders. It scores a notch below the #1 pick and Thorne only because those run a per-batch, multi-stage or third-party-certified program. If your bar is 'real, independent testing,' Nutricost clears it comfortably.
On cost per dose Nutricost is essentially level with the cheapest bulk bag — a few cents per 3 g serving. The only reason it does not win outright is size: it sells mainly in a 1 lb tub of roughly 150 servings, so heavy nightly users reorder more often, and the very largest 1 kg bags edge it out slightly on cost per gram. That is a packaging difference, not a quality one, which is exactly why this is a co-recommendation rather than a downgrade.
Buying the tidier tub does not change what glycine is: 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 3 g nightly for one to two weeks before judging, and stack it with a cool room and consistent sleep timing. Nutricost is one of the two best ways to take glycine for sleep — it is still a small, well-tolerated edge, not a cure.
Nutricost Glycine Powder is a genuine co-recommendation, not a runner-up by default. It is 100% plain glycine, non-GMO and gluten-free, portioned at the studied 3 g dose with a measuring scoop included so you hit that dose effortlessly, and independently ISO-accredited tested — all at a cost per dose within a rounding error of the cheapest bulk bag. It sits at #2 only on two small margins: it is marginally pricier per gram than the largest 1 kg bulk bags, and its testing is ISO-accredited rather than the per-batch, multi-stage program the #1 pick runs. Neither affects the experience. If you would rather have a tidy tub with a scoop than a no-frills bulk bag, buy this instead of #1 and you lose nothing that matters. As with every glycine product, take 3 g, 30 to 60 minutes before bed, give it one to two weeks, and stack it with good sleep timing and a cool room.
Check Nutricost · 100% plain glycine powder · scoop included · 1 lb on AmazonThe overall winner — the same plain glycine and 3 g dose at the lowest cost per gram in the category, per-batch tested. Buy it if you want the absolute cheapest dose and do not mind a no-frills bulk bag.
See it on the list →Pure glycine from a household name with decades of in-house QC, widely stocked for an easy offline backup. Its label serving is 1 g, so you measure ~1 rounded teaspoon for the 3 g sleep dose.
See it on the list →If you would rather swallow capsules than mix a powder, Thorne has the best testing pedigree in a 1 g cap, so the 3 g dose is three caps not six — at several times the powder cost per gram.
See it on the list →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).
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.
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.
