Glycine looks simple on a supplement label.

Then you begin comparing products.

One bottle gives you 1,000 mg in a single capsule. Another requires three capsules for 1,500 mg. Some contain only glycine, while others pair it with NAC to support glutathione production.

Even the best glycine supplements are not designed for the same purpose.

So, before buying, ask one question:

What do you want your glycine supplement to support?

A pure glycine capsule may make sense when simplicity, price, or adjustable intake matters most. Glycine combined with NAC may fit someone looking for broader glutathione and cellular health support.

That distinction makes the comparison far easier.

What Is Glycine?

Glycine is a small amino acid that your body can produce and also gets from food.

It helps form proteins and takes part in several normal processes. Glycine is found in collagen and is also one of the three amino acids used to make glutathione, along with cysteine and glutamate. (1)

This explains why people look into glycine supplements for more than one reason.

Common areas of interest include:

• Sleep quality

• Relaxation

• Collagen production

• Glutathione production

• Exercise recovery

• Cellular health

• Healthy aging

Research support is not equally strong across every area. A good product comparison should separate established biological roles from early human findings.

What Does Research Say About Glycine and Sleep?

Glycine has gained attention as a sleep supplement, but the human research is still small.

Several studies used 3 grams of glycine before bedtime.

One study looked at healthy adults during three nights of restricted sleep. Participants took either 3 grams of glycine or a comparison powder before bed. Glycine was linked with lower self-reported fatigue and better performance on one attention test the following day. (2)

Earlier small studies in people dissatisfied with their sleep also reported changes in subjective sleep quality after taking 3 grams before bed. A 2024 systematic review noted that the evidence is promising, but the number and size of human studies remain limited. (1)

This matters when reading labels.

Most capsule products in this comparison provide between 1 and 1.5 grams per labeled serving. That does not mean smaller amounts have no value, but they should not be presented as identical to the 3-gram research setup.

How We Compared the Products

We looked at six points:

• Glycine amount per labeled serving

• Number of capsules required

• Bottle size and number of servings

• Single-ingredient versus combined formula

• Public testing and manufacturing information

• Price at the time of review

We did not rank products based on customer star ratings. Reviews can help show user experience, but they cannot prove that a supplement will work the same way for everyone.

Quick Comparison: 5 Best Glycine Supplements

1. Omre Glycine + NAC - Best for Glycine Plus NAC and Glutathione Support

At Omre, we did not create a glycine-only product.

We paired glycine with NAC because both provide materials the body uses during glutathione production. Glycine supplies one amino acid directly, while NAC provides a source of cysteine.

Each two-capsule serving contains:

• 1,000 mg glycine

• 500 mg N-Acetyl L-Cysteine, NAC

• 1,500 mg total active ingredients

• 30 servings per bottle

GlyNAC research has explored this combination in older adults.

In one randomized study, 24 adults between ages 61 and 80 received either GlyNAC or a comparison formula for 16 weeks. Researchers reported changes in glutathione status, oxidative stress measures, mitochondrial function, and several physical measures in the GlyNAC group. (3)

The study was small and used much higher body-weight-based amounts than our formula. Our product should not be expected to copy those research conditions.

We designed Omre Glycine + NAC for daily baseline support, with two capsules rather than a large number of capsules or scoops.

Quick Specifications

• Price: $35 one-time purchase

• Subscription price: $33.25

• Cost per serving: About $1.17, or $1.11 with subscription

• Glycine: 1,000 mg

• NAC: 500 mg

• Serving size: 2 capsules

• Bottle size: 30 servings

• Suggested use: 2 capsules in the morning with food

• Testing: Third-party tested for amount, purity, bacteria, fungus, contaminants, and heavy metals

• Manufacturing: Made in the USA in GMP-certified facilities

• Free from: Gluten, dairy, soy, artificial colors, preservatives, and artificial flavoring

• Guarantee: 30-day money-back guarantee

Who It Fits

Omre may suit someone who wants:

• Glycine and NAC in one formula

• Support for natural glutathione production

• A simple two-capsule routine

• Published quality information

• A formula designed around healthy aging and cellular support

2. Life Extension Glycine - Best for 1,000 mg in One Capsule

Life Extension offers one of the simplest options in this comparison.

Each vegetarian capsule provides 1,000 mg of glycine, so users can reach a full 1-gram serving without taking multiple capsules.

Quick Specifications

• Price: $12 one-time or $11 with AutoShip through Life Extension

• Glycine: 1,000 mg per capsule

• Serving size: 1 capsule

• Bottle size: 100 capsules

• Servings: 100

• Other ingredients: Vegetable cellulose and ascorbyl palmitate

• Diet details: Vegetarian, gluten-free, and non-GMO

• Suggested use: 1 capsule, one to three times daily

Who It Fits

This may suit people who want:

• Pure glycine without NAC

• 1,000 mg in one capsule

• A low cost per 1-gram serving

• Flexible daily use

3. Nutricost L-Glycine - Best Value Among the Single-Capsule Options

Nutricost also provides 1,000 mg of glycine in one vegetarian capsule.

The bottle contains 120 capsules, giving it the largest number of 1-gram single-capsule servings among the products compared here.

Quick Specifications

• Price: $15.95 one-time or $14.35 with Subscribe & Save at review time

• Glycine: 1,000 mg per capsule

• Serving size: 1 capsule

• Bottle size: 120 capsules

• Servings: 120

• Diet details: Vegetarian, non-GMO, and gluten-free

• Testing: Independently tested by ISO-accredited laboratories

• Manufacturing: Made in a GMP-compliant, FDA-registered facility

• Other ingredients: Capsule material, rice extract blend, stearic acid, magnesium stearate, and silica

Who It Fits

Nutricost may appeal to shoppers who want:

• A low price per 1-gram serving

• One capsule per serving

• Independent laboratory testing

• A larger bottle

4. Thorne Glycine - Best for a Large Bottle and Adjustable Intake

Thorne Glycine contains 250 vegetarian capsules.

Each two-capsule serving provides 1,000 mg, which means each capsule contains 500 mg. This makes it easy to adjust intake in 500 mg steps.

Quick Specifications

• Price: $31 one-time or $26.35 with Subscribe & Save at review time

• Glycine: 1,000 mg per two-capsule serving

• Glycine per capsule: 500 mg

• Serving size: 2 capsules

• Bottle size: 250 capsules

• Servings: 125

• Free from: Gluten, dairy, and soy

• Testing: Third-party certified

• Suggested use: 2 capsules, one to three times daily

Who It Fits

Thorne may suit shoppers who want:

• A large bottle

• A well-known supplement company

• Third-party certification

• The option to adjust intake by 500 mg at a time

5. Pure Encapsulations Glycine - Best for a 1,500 mg Labeled Serving

Pure Encapsulations provides 1,500 mg of free-form glycine per three-capsule serving.

That is the highest labeled glycine serving among the five products compared here.

Quick Specifications

• Price: $35 one-time or $33.25 with Subscribe & Save at review time

• Glycine: 1,500 mg per serving

• Glycine per capsule: 500 mg

• Serving size: 3 capsules

• Bottle size: 180 capsules

• Servings: About 60

• Other ingredients: Cellulose capsule, plant fiber, and ascorbyl palmitate

• Diet details: Vegan, gluten-free, and non-GMO

• Suggested use: 3 capsules, one to two times daily between meals

Who It Fits

Pure Encapsulations may suit people who want:

• A 1,500 mg labeled serving

• A short supporting-ingredient list

• A vegan glycine formula

• Flexibility to use 500 mg capsule increments

Why We Paired Glycine With NAC

Glutathione is made from glycine, cysteine, and glutamate.

Most cells have access to glutamate. Glycine and cysteine can become limiting materials in some situations, which is why researchers have studied them together.

NAC provides a source of cysteine. Glycine supplies another direct part of the glutathione structure.

This does not mean everyone needs both ingredients. It means the combination has a clear nutritional reason behind it.

At Omre, we prefer focused formulas that are easy to explain.

Our formula contains:

• Glycine

• NAC

• No proprietary blend

• No long list of unrelated ingredients

You know what each ingredient contributes and how much you receive.

A Simple Formula for a Clear Goal

Some shoppers need pure glycine.

Others want glycine as part of a broader glutathione-support routine.

Neither choice is wrong.

At Omre, we created Glycine + NAC for adults who want the second route. Each serving gives you 1,000 mg of glycine and 500 mg of NAC in two vegan capsules.

You also receive:

• Third-party quality testing

• Clear ingredient amounts

• US manufacturing in GMP-certified facilities

• 30 servings per bottle

• A 30-day money-back guarantee

See Omre Glycine + NAC and Review the Full Label

Choose a formula built around a clear purpose, not the loudest promise.

FAQs

What is glycine?

Glycine is an amino acid used to form proteins, collagen, and glutathione. Your body can make it, and you also get it from protein-containing foods.

What is the best glycine supplement?

The best option depends on your goal. Pure glycine may suit sleep-focused or single-ingredient routines, while glycine plus NAC may suit people interested in glutathione and cellular support.

Does glycine support sleep?

Small human studies using 3 grams before bed reported improvements in selected sleep and next-day fatigue measures. The evidence remains limited, and many capsule products provide less than 3 grams per labeled serving.

Is glycine powder better than capsules?

Powder makes larger serving amounts easier without several capsules. Capsules are simpler to measure, carry, and add to a daily routine.

What is the difference between glycine and GlyNAC?

Glycine is one amino acid. GlyNAC combines glycine with NAC, which supplies a source of cysteine for the body’s glutathione production pathway.

References

1. Soh J, et al. The Effect of Glycine Administration on the Characteristics of Physiological Systems in Human Adults: A Systematic Review. GeroScience. 2024.

2. Bannai M, et al. The Effects of Glycine on Subjective Daytime Performance in Partially Sleep-Restricted Healthy Volunteers. Frontiers in Neurology. 2012.

3. Kumar P, et al. Supplementing Glycine and N-Acetylcysteine in Older Adults. The Journals of Gerontology: Series A. 2023.