NOW Foods Glycine Pure Powder is the powder to buy if you would rather trust a name you already recognize — and be able to grab a bottle at a local store. It is 100% pure glycine, vegan and non-GMO, from a brand with one of the most respected in-house QC operations in the supplement industry, and it mixes and tastes just like the bulk options: naturally sweet, dissolves clear, no fillers. The one practical nuance keeps it at #3 rather than higher: NOW lists the serving at 1 g (a quarter teaspoon), so for the studied 3 g sleep dose you measure roughly a rounded teaspoon yourself rather than taking one pre-portioned scoop. It also costs a touch more per gram than the bulk-bag specialists above it. Neither is a quality knock — the glycine is excellent — they are just the reasons the two dedicated bulk powders edge it out. For a household-name powder you can find anywhere, this is the pick. Here is the full breakdown.
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Read the complete Glycine guide →100% pure glycine, vegan and non-GMO, no fillers or blend — the free-form glycine the sleep studies used. Nothing disqualifying and nothing to fault about the ingredient. It scores level with the top powders on purity; NOW's pure-glycine positioning is exactly what this ranking asks for.
NOW operates extensive in-house analytical laboratories under GMP and is one of the most audited brands in the industry — a genuinely strong QC pedigree. The reason it does not top this axis is that its verification is primarily in-house rather than per-batch third-party testing (the #1 pick) or third-party certification (Thorne), but for a commodity ingredient NOW's operation is highly trustworthy.
The one axis where it clearly trails the top two powders. NOW's label serving is 1 g (a quarter teaspoon), so for the studied 3 g sleep dose you measure about a rounded teaspoon yourself rather than taking a single pre-portioned 3 g scoop. Entirely doable, but it introduces a small by-eye measurement the scooped powders remove.
Glycine's natural sweetness applies fully: NOW's pure powder dissolves clear in water or tea and tastes faintly sweet with no added flavoring, mixing cleanly with no grit. It is level with the best powders here — the ingredient does the work, and NOW's is clean.
Strong value — a few cents per 3 g dose — just edged out by the bulk-bag specialists. Glycine is cheap and NOW passes that through, but a 1 lb bottle from a household brand carries a slight premium over a 1 kg warehouse bag. You pay a little for the name and the shelf availability, which is a fair trade for many buyers.
“100% pure glycine, vegan and non-GMO.”
The listing describes a pure, vegan, non-GMO 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.
“Label serving is 1 g (1/4 tsp).”
NOW lists the serving at approximately 1 g per quarter teaspoon. Accurate — and the honest reason the review flags that you measure about a rounded teaspoon for the studied 3 g sleep dose rather than taking one pre-portioned scoop.
“Manufactured with NOW's in-house analytical QC under GMP.”
NOW's in-house analytical laboratories and GMP manufacturing are well documented and among the most respected in the industry. Appropriate, real verification for a commodity amino acid — the claim is accurate.
“Promotes restful 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. A reasonable category claim, not a proven product-specific outcome.
The glycine inside is chemically identical to the bulk bags, so what NOW really sells is recognition and availability. It is a household brand stocked in most health stores, which makes it the simplest offline backup if you run out mid-week, and many buyers reasonably prefer a name they already know over an anonymous warehouse bag. That is a legitimate reason to pick it — you are paying a small premium for trust and convenience, not for a better molecule.
For a commodity amino acid, verified purity is the whole game, and NOW's extensive in-house analytical laboratories and GMP manufacturing are among the most respected in the industry. It scores just below the #1 pick and Thorne on the testing axis only because those run per-batch third-party or third-party-certified programs; NOW's verification is primarily in-house. For a plain glycine powder, that is highly trustworthy and part of why the brand has the reputation it does.
NOW lists its serving at 1 g (a quarter teaspoon), whereas the top two powders portion 3 g per scoop. So for the studied sleep dose you measure roughly a rounded teaspoon yourself. It is easy, but it reintroduces a small by-eye measurement the scooped powders eliminate — which is exactly why this sits at #3 despite level quality. If effortless, exact dosing matters most to you, BulkSupplements (#1) or Nutricost (#2) are the better fit; if you want the recognizable brand, measure the teaspoon and you are fine.
Choosing the household name 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 about 3 g nightly for one to two weeks before judging, and stack it with a cool room and consistent sleep timing. NOW is a trustworthy way to take glycine for sleep — it is still a small, well-tolerated edge, not a cure.
NOW Foods Glycine Pure Powder is the pick for a buyer who wants a household name they already trust and can grab at a local store. The glycine is 100% pure, vegan and non-GMO, the in-house QC pedigree is excellent, and it mixes and tastes just like the bulk options — naturally sweet, dissolves clear. It sits at #3 for two practical reasons, neither a quality knock. NOW lists the serving at 1 g, so for the studied sleep dose you measure roughly a rounded teaspoon (about 3 g) yourself instead of taking a single pre-portioned scoop, and it costs a touch more per gram than the dedicated bulk bags. If effortless, exact scooping and the lowest price matter most, BulkSupplements (#1) or Nutricost (#2) win; if the recognizable brand and shelf availability matter more, this is the one. As with every glycine product, take about 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 NOW Foods · 100% pure glycine powder · 1 lb (454 g) on AmazonThe overall winner — plain glycine at the lowest cost per gram, per-batch tested, with a 3 g scoop. Buy it if you want the cheapest dose and one pre-portioned scoop over a household-brand name.
See it on the list →A near-tie value pick with the measuring scoop included in a tidy tub, so the 3 g dose is portioned for you. Choose it over NOW if you want a scoop-in-the-tub at value pricing.
See it on the list →If you would rather swallow capsules than measure powder, Thorne has the best testing pedigree in a 1 g cap, so the 3 g dose is three caps — 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.
