Best Glycine Supplement: Powder vs Capsules, by Price

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Glycine is the simplest amino acid, and as a supplement it is mostly taken at bedtime in the hope of better sleep. A small trial of healthy people whose sleep was cut short found 3 g before bed was linked to less daytime fatigue, and a small trial in older adults tested glycine with NAC (GlyNAC). Both are small, so we rate the evidence D. Read the glycine guide first. This page compares the four glycine products we have price and label data for.

Short answer: Best overall (US$): Thorne Glycine capsules (NSF Contents Certified; the only named listing); Best budget (US$): NOW Glycine Pure Powder (sale price); UK: Bulk Glycine powder is the only product with a UK price (sale price to Nov 10, 2026). Prices, testing and every shop are in the picks below.

How we rank

We only rank products that are in our product data file, and we use only what that file records:

1. Form and amount. Three products are plain glycine powder and one is capsules. Serving sizes differ: 1 g (Thorne, per 2 capsules), 2 g (Bulk) and 3 g (NOW and Nutricost). We compare the grams of glycine per serving and scale every price to 3 g.
2. Third-party testing, as listed. We note a named testing program (for example NSF Certified for Sport) when our data lists one. Where the data says “brand statement”, we say so and do not count it as verified by us.
3. Price per daily dose. We divide the pack price by the servings per pack, then scale to our basis: 3 g of glycine a day, the amount used in the sleep trial we cite. Serving sizes on the labels are 1 g, 2 g and 3 g, so each price is scaled to 3 g. It is a price basis, not a recommended dose. Prices in different currencies are not converted, so $ and £ are only compared within their own currency.

Winner labels. “Best overall” goes to the cheapest product with a named testing program in that currency. “Best budget” goes to the lowest price per daily dose in that currency, whatever the testing. “Best tested” is only used when one product lists clearly more named programs than the rest. If no product qualifies for a label, we leave that label out.

Sale prices. NOW’s $22.49 is a sale price (regular $29.99, which gives $29.99 ÷ 151 = $0.199 per 3 g). Bulk’s £4.99 is a sale price that runs to Nov 10, 2026 (regular £19.99, which gives £19.99 ÷ 250 × 3 ÷ 2 = £0.120 per 3 g). Recheck before you buy.

Unverified prices. Where a price was read through a search tool instead of on the shop’s own page (Nutricost and Bulk at Amazon), the table says so and no pick relies on it. Nutricost’s Amazon.com price looks slightly lower than NOW’s in that snapshot.

What counts as testing. Only Thorne has a named listing. NOW’s Intertek GMP certification covers the facility, and Nutricost’s lab claim names no certificate, so neither counts.

What we did not do. We have not tested these products ourselves, in a lab or by taking them. We did not rank by commission. Prices change, so each price shows the date it was checked. More in How we rank.

Price per daily dose

Basis: 3 g of glycine a day, the amount used in the sleep trial we cite. Serving sizes on the labels are 1 g, 2 g and 3 g, so each price is scaled to 3 g. It is a price basis, not a recommended dose. Every number below is worked out from the pack price, servings per pack and amount per serving in our product data.

US dollar prices ($)

Product (retailer)	Amount per serving	Pack price (checked)	Price per serving	Price per daily dose	Testing named in our data
Nutricost Glycine powder, 454 g (Amazon.com)	3 g glycine per serving	$21.95 (Nov 3, 2026; price read through a search tool, not on the shop page)	$21.95 ÷ 151 = $0.145	$0.145	None named
NOW Foods Glycine Pure Powder, 1 lb (454 g) (NOW Foods)	3 g glycine per serving (about 1 tsp)	$22.49 (Nov 3, 2026)	$22.49 ÷ 151 = $0.149	$0.149	None named
Nutricost Glycine powder, 454 g (Nutricost)	3 g glycine per serving	$24.97 (Nov 3, 2026)	$24.97 ÷ 151 = $0.165	$0.165	None named
Thorne Glycine capsules, 250 capsules (Thorne)	2 capsules: 1 g glycine	$31.00 (Nov 3, 2026)	$31.00 ÷ 125 = $0.248	$0.248 × 3 ÷ 1 = $0.744	NSF Contents Certified (Thorne Glycine is listed in NSF’s certified dietary supplement directory; the NSF listing shows a 6-capsule serving, so check the pack)
Thorne Glycine capsules, 250 capsules (PureFormulas)	2 capsules: 1 g glycine	$31.00 (Nov 3, 2026)	$31.00 ÷ 125 = $0.248	$0.248 × 3 ÷ 1 = $0.744	NSF Contents Certified (Thorne Glycine is listed in NSF’s certified dietary supplement directory; the NSF listing shows a 6-capsule serving, so check the pack)

UK prices (£)

Product (retailer)	Amount per serving	Pack price (checked)	Price per serving	Price per daily dose	Testing named in our data
Bulk Glycine powder 500 g (Bulk)	2 g glycine (about 2.5 scoops; Bulk suggests 1 to 2 g twice a day)	£4.99 (Nov 3, 2026)	£4.99 ÷ 250 = £0.020	£0.020 × 3 ÷ 2 = £0.030	None named
Bulk Glycine powder 500 g (Amazon.co.uk)	2 g glycine (about 2.5 scoops; Bulk suggests 1 to 2 g twice a day)	£4.99 (Nov 3, 2026; price read through a search tool, not on the shop page)	£4.99 ÷ 250 = £0.020	£0.020 × 3 ÷ 2 = £0.030	None named

Capsules cost about five times as much per 3 g as the powders in dollars ($0.744 for Thorne against $0.149 for NOW).

How to start

In the sleep trial, 3 g was taken before bedtime. That is a study amount, not a recommendation, and the studies we found were short, so long-term effects are unknown. The labels here give 1 g (Thorne, per 2 capsules), 2 g (Bulk) or 3 g (NOW and Nutricost) per serving. See the glycine guide.

Talk to your doctor or pharmacist

Talk to your doctor or pharmacist before you start any supplement, especially if you are pregnant or breastfeeding, take prescription medicine, or have a health condition. This matters especially if you are pregnant, breastfeeding, under 18, or have kidney or liver disease, because we found no reliable safety data in these groups. The full guide has the evidence, safety notes and citations.