Best 10 Glycine Supplements of 2025

Glycine supplements may support better sleep, a calmer mind, and improved brain function. They could also help with muscle recovery and joint health, allowing you to stay energetic throughout the day.

Although your body produces glycine on its own, taking it as a supplement might help enhance GABA activity and improve mental clarity.

The market has many glycine supplements in different forms, such as capsules, tablets, and powders. Some products might have higher purity, better absorption, or added ingredients for extra support. Choosing the right one could make a big difference in how well it works for your needs.

This guide highlights the 10 best glycine supplements, reviewed for their quality, effectiveness, value, and ease of use. We will also evaluate and compare the supplements and analyze their potential drawbacks to help you make an informed decision.

10 Best Glycine Supplements

1. Pure Encapsulations Glycine

   

   Pure Encapsulations Glycine provides synthetically produced glycine, a non-essential amino acid that may help in supporting nervous system function, detoxification, and organ health. This supplement may help promote a calm, balanced nervous system and support healthy kidney and liver function through its involvement in phase II detox pathways.

   Pure Encapsulations Glycine includes vitamin C in the form of ascorbyl palmitate, a fat-soluble antioxidant derived from the fermentation of corn dextrose. This form of vitamin C might improve the stability of formulations, especially those containing oils or fat-based ingredients, as it resists degradation more effectively than water-soluble ascorbic acid.

   The makers recommended taking three Pure Encapsulations Glycine capsules once or twice daily between meals, offering a convenient way to integrate glycine into your daily wellness routine.
   

   Pros

   • May support deeper, more restful sleep.
   • Might help reduce symptoms of anxiety by calming the nervous system.
   • Could enhance memory and cognitive performance.

   Cons

   • Some people may experience stomach discomfort or bloating after taking glycine.
   • You could find swallowing large glycine capsules difficult, especially at higher doses.

2. Thorne Glycine

   

   As per the official website, Thorne Glycine provides 1 gram of highly purified glycine per 2-capsule serving and is designed to support relaxation, metabolic balance, and detoxification.

   Glycine, in this formula, functions as an inhibitory neurotransmitter in the brainstem and the spinal cord, which may help reduce stress, improve sleep quality, and regulate nervous system activity, especially useful during jet lag or irregular sleep cycles.

   The supplement also plays a critical role in supporting toxin elimination and enhancing glutathione production. It may help modulate inflammation by influencing cytokine activity and support metabolic health by regulating glucose usage and promoting bile acid synthesis.

   The makers state that  Thorne Glycine can contribute to creatine production alongside arginine and methionine, which are essential for muscle energy and structural health.
   

   Pros

   • May contribute to collagen production for healthy skin and joints.
   • Might help regulate blood sugar levels.
   • Could aid in muscle growth and repair.

   Cons

   • Glycine supplements may cause loose stools.
   • Taking these capsules on an empty stomach might lead to nausea for some people.

3. Life Extension Glycine

   

   According to the manufacturer, Life Extension Glycine offers a high-potency dose of 1000 mg per vegetarian capsule, providing an efficient way to meet daily glycine needs. This supplement claims to support neurological health, emotional stability, and restful sleep by functioning as a calming neurotransmitter.

   Life Extension Glycine might also support antioxidant production, especially glutathione, along with internal cleansing, immune response, and collagen synthesis, which may help joints, skin, and muscles.

   As per the makers, Life Extension Glycine aids in regulating blood sugar, supporting cardiovascular health, and protecting against the formation of advanced glycation end-products, which are linked to aging and diseases. This formula might also support gastrointestinal function, enhancing nutrient absorption and metabolic function.
   

   Pros

   • May support liver detoxification processes.
   • Might promote wound healing by enhancing tissue regeneration.
   • Could reduce fatigue by improving mitochondrial function.

   Cons

   • Potential for allergic reaction.
   • You might feel dizzy after taking the supplement.

4. Micro Ingredients L-Glycine Powder

   

   Micro Ingredients L-Glycine Powder claims to provide 1000mg of glycine per 1 scoop and is available in a bulk, unflavored powder form, allowing for flexible dosing. This free-form amino acid serves as a key inhibitory neurotransmitter and may help support calmness, healthy sleep cycles, and nervous system balance.

   The makers highlight that Micro Ingredients L-Glycine Powder is free from GMOs, gluten, soy, fillers, and other common allergens. It also dissolves easily in liquids and includes a scoop for accurate dosing.
   

   Pros

   • May act as a neurotransmitter that supports mental clarity.
   • Might help protect against oxidative stress.
   • May improve symptoms of schizophrenia when used adjunctively.

   Cons

   • The natural, mild, sweet taste of glycine powder could be unpleasant if you’re not used to it.
   • You may find it difficult to measure consistent doses with loose powder forms.

5. Pristines Glycine

   

   Pristines Glycine provides 1000 mg of pure glycine per capsule, which could support sleep, metabolic reset, and muscle repair. This formula may help reduce sleep disturbances and promote deep, restorative rest, without the need for melatonin.

   The makers state that Pristines Glycine could be beneficial for you if you have an active lifestyle, as glycine plays a role in tissue repair and post-exercise recovery. It may also help detox pathways, which could support kidney function and general metabolic balance.
   

   Pros

   • Could support digestive health through bile acid production.
   • May help reduce inflammation in the body.
   • Might lower risk factors for metabolic syndrome.

   Cons

   • High doses could lead to drowsiness or excessive sedation.
   • You may notice vivid dreams or sleep disturbances.

6. Horbäach Glycine Powder

   

   Horbäach Glycine Powder may provide 1,000 mg of free-form glycine per gram, giving you a flexible way to supplement this non-essential amino acid. While your body can produce glycine, additional intake may help support deeper sleep, neurological stability, and natural detox processes, especially when daily demands increase. The makers claim that this unflavored, vegetarian-friendly powder blends easily into water or juice and contains no unnecessary fillers.
   

   Pros

   • Could play a role in hemoglobin synthesis.
   • May assist in maintaining healthy skin elasticity.
   • Might improve flexibility and joint mobility.

   Cons

   • It might interact with certain medications like clozapine or antipsychotics.
   • May require multiple servings per day, which may feel inconvenient.

7. Vital Nutrients Glycine Powder

   

   As per the official website, Vital Nutrients Glycine Powder provides 4 grams of pure glycine per rounded teaspoon, which could support cognitive function, stress resilience, and healthy sleep cycles. It might also help regulate nerve impulses and promote mental calm, which may be particularly helpful for occasional anxiousness or sleep disturbances.

   Vital Nutrients Glycine Powder could also support detoxification by helping produce glutathione, a critical intracellular antioxidant. Glutathione plays an essential role in neutralizing free radicals, removing toxins, and supporting liver function. This formula could indirectly assist in protecting your cells from oxidative damage and promoting efficient metabolic waste clearance by helping maintain optimal levels.
   

   Pros

   • Could support better body composition in some people.
   • May enhance creatine synthesis for better physical performance.
   • Might reduce daytime sleepiness.

   Cons

   • You could encounter a temporary drop in energy levels when first starting the product.
   • Some people might find the pricing higher compared to food-based glycine sources.

8. Bulk Supplements Glycine Capsules

   

   BulkSupplements Glycine Capsules may support neurological health, restful sleep, cardiovascular function, and liver wellness. They could help promote better sleep by calming the nervous system and helping regulate circadian rhythms. Taking BulkSupplements Glycine Capsules during nighttime might help you fall and stay asleep without next-day grogginess. It could also support cardiovascular health by contributing to nitric oxide production, which may aid in maintaining normal blood flow and vascular tone.
   

   Pros

   • May support mood regulation by influencing serotonin receptors.
   • Could act as an inhibitory neurotransmitter to calm brain activity.

   Cons

   • You might experience mild headaches when starting glycine supplementation.
   • You may notice a metallic or unpleasant aftertaste.

9. Now Foods Glycine

   

   Now Foods Glycine provides a substantial 3,000 mg of pure glycine per serving, delivered in a convenient three-capsule format. It may provide neurological support, as glycine plays a direct role in neurotransmission by interacting with NMDA receptors in the brain.

   Now Foods Glycine could have a calming effect on your central nervous system, making it a suitable choice if you are dealing with occasional stress, overstimulation, or difficulty concentrating.

   Due to glycine’s inhibitory effect on neuronal signaling, consistent use of Now Foods Glycine may also help promote faster sleep onset and deeper, more restorative sleep. It might help maintain optimal glutathione levels, especially if you are exposed to oxidative stress or environmental toxins.

   As per the manufacturer, Now Foods Glycine may support glycogen storage and glucose regulation, which could help maintain steady energy levels during periods of extended physical or mental effort.
   

   Pros

   • May enhance resilience to stress.
   • Could support glutathione production for cellular defense.
   • Might help in managing symptoms of ADHD in some people.

   Cons

   • Glycine may not show noticeable effects immediately, leading to disappointment.
   • You could experience water retention or puffiness with high doses.

10. Double Wood Supplements Glycine

    

    According to the official website, Double Wood Supplements Glycine provides 1,000 mg of pure glycine per two capsules, which could support your nervous system and sleep quality. It may also help promote more restful sleep by supporting the body’s ability to lower core temperature and enhance GABAergic activity, two key mechanisms associated with deeper, more restorative rest. The formulation’s high potency can also be useful for supporting daytime mental clarity, as glycine plays a role in balancing excitatory and inhibitory neurotransmitters.

    Double Wood Supplements Glycine includes pure glycine content, which could also support mental clarity and cognitive steadiness during the day. It may help regulate the balance between excitatory and inhibitory neurotransmitters, which could prevent overstimulation and mental fatigue. This can be helpful in high-stress situations or during prolonged mental focus.
    

    Pros

    • Could help stabilize mood swings in some mental health conditions.
    • May support cardiovascular health by reducing homocysteine levels.
    • Might have protective effects against certain neurodegenerative diseases.

    Cons

    • It is not always necessary if your diet is already protein-rich.
    • The effectiveness may vary depending on your health condition.

Side Effects of Best Glycine Supplements

1. Stomach Upset

   Glycine supplements may trigger stomach upset in some people, particularly when taken in large doses or without food. Glycine stimulates gastric acid secretion, which may increase stomach acidity and irritate the mucosal lining. This can lead to symptoms like bloating, mild cramping, or a burning sensation in the upper abdomen. Glycine also supports the production of bile salts, and when introduced in supplemental form, they may disrupt the normal digestive rhythm, especially if you have a sensitive gastrointestinal tract. You may experience discomfort shortly after taking glycine powders or capsules, particularly if your digestive system is not used to isolated amino acids.

2. Vomiting

   Vomiting is a less common but notable side effect of glycine supplementation, typically occurring at higher doses (often above 10 grams per day). Glycine may function as an inhibitory neurotransmitter in the central nervous system and might influence brain regions responsible for nausea regulation, such as the area postrema. If glycine levels rise too quickly in the bloodstream, it may overstimulate these centers, triggering symptoms like nausea, dizziness, and ultimately vomiting. You may also experience this side effect if you are taking glycine products alongside other CNS-acting substances or medications that heighten sensitivity to neurotransmitter fluctuations.

3. Loose Stools

   Loose stools can occur when glycine supplements are not fully absorbed in the small intestine, especially at higher doses. The unabsorbed glycine can act osmotically, drawing water into the colon and speeding up transit time. This results in looser stool consistency and more frequent bowel movements. In some cases, glycine products may also ferment in the gut microbiota, producing gas, bloating, and urgency. These symptoms are more likely when starting glycine supplementation suddenly or using formulations that contain added sweeteners or fillers that may also have a laxative effect. If you have irritable bowel syndrome or any digestive sensitivities, you may be more prone to this side effect.

How Did We Evaluate The Best Glycine Supplements?

1. Brand Reputation

   To identify the best glycine supplements, we considered the reputation of the brands behind them. When it comes to brand reputation for glycine supplements, Now Foods, Life Extension, and Pure Encapsulations stand out at the top. Now Foods holds an A+ rating from the BBB and is widely recognized for quality, affordability, and third-party testing, even without a Trustpilot presence. Life Extension follows closely with a 4.4 Trustpilot score and a strong reputation for research-backed formulations. Pure Encapsulations, though lacking public-facing consumer reviews, maintains an A- BBB rating, making it a solid choice for those prioritizing purity and practitioner-grade quality.

   Thorne, Double Wood, and Vital Nutrients occupy the middle tier. Thorne has a strong clinical reputation but is held back by a B- BBB rating and no Trustpilot data. Double Wood shows moderate consumer satisfaction with a 3.5 Trustpilot rating and an A+ BBB score, indicating satisfactory issue resolution despite occasional concerns.

   Vital Nutrients earns credibility in professional settings and has a 3.8 Trustpilot rating. However, this rating is based on only two reviews, making it insufficient to assess the brand’s overall reputation accurately. The brand’s absence from the Better Business Bureau (BBB) further limits transparency and public accountability.

   Brands like Horbäach and Micro Ingredients are more neutral. Horbäach has an A- BBB rating but no consumer reviews to validate product experience. Micro Ingredients also lacks Trustpilot and BBB presence, leaving a gap in consumer trust signals despite its popularity on marketplaces like Amazon.

   Bulk Supplements and Pristines raise more concerns. Bulk Supplements has a low 1.9 Trustpilot score and a B rating on BBB, suggesting frequent issues with quality control or service. Pristines lacks any third-party credibility or verified feedback, making its reliability unclear. These brands may offer budget-friendly options, but the trade-off in trust and transparency is worth noting.

2. Refund Policy

   When evaluating glycine supplements, we looked closely at each brand’s refund policy, which often reflects how much confidence a company has in its product and how it treats its customers post-purchase.

   Life Extension ranked highest due to its 365-day return policy, allowing refunds, exchanges, or replacements even for opened products. This extended window may give you the freedom to try the product without pressure. Double Wood Supplements followed closely with a money-back guarantee on the first bottle of any product, even in multipacks. You can return unused bottles within 30 days for a full refund, although you must cover return shipping. BulkSupplements also stood out by allowing partial refunds for opened products, a rare option, though shipping and discounts aren’t refunded, and wholesale orders are excluded. Horbäach offered a straightforward 30-day full refund policy, with no restocking fee, but without covering return shipping.

   Brands like Now Foods, Micro Ingredients, and Vital Nutrients fell into the midrange. Now Foods accepts unopened returns within 30 days for orders placed on its official site, but doesn’t cover third-party purchases. Micro Ingredients adds a $10 handling fee and requires customers to pay return shipping, even on timely returns. Vital Nutrients only allows returns of unopened products within 30 days and involves preauthorization with a valid RMA number, placing more responsibility on the customer to follow procedures.

   We ranked Pure Encapsulations and Thorne lower due to more restrictive policies. Pure Encapsulations requires preapproval within 30 days, a return within 14 days of authorization, a 15% processing fee, and no refund on shipping unless it’s an error. Thorne offers a longer 60-day window but applies a steep 25% restocking fee, significantly cutting into the refund amount, especially on higher-priced items.

   Pristines offered the least favorable return terms. The policy lacks clarity, doesn’t mention a return window, provides no return label, and requires you to pay for all return-related costs, including unspecified shipping and handling fees. The lack of transparency and customer support made it the least consumer-friendly among all the glycine brands we assessed.

3. Value for Money

   To evaluate the best glycine supplements for value, we considered total cost, capsule or powder quantity, and brand quality.

   Double Wood Supplements Glycine costs $19.95 for 300 capsules, offering the best deal overall, including high volume, third-party testing, and reliable potency.  Bulk Supplements provides 270 capsules for $22.97, also delivering strong value for those wanting a no-frills, high-quantity option.

   In powder form, Micro Ingredients gives you 1 kg for $34.95, and Horbäach offers 48 oz (approx. 1.36 kg) for $25.99, both suitable for long-term users due to their extremely low cost per gram.

   Thorne provides 250 capsules for $29, and Life Extension offers 100 capsules for $12, both from reputable brands and well-suited for regular supplementation.

   Pristines Glycine costs $16.99 for 120 capsules, offering fair pricing, though it lacks strong brand visibility. Now Foods is priced at $16.99 for just 100 capsules, making it one of the more expensive options for its size despite solid brand trust.

   Premium options like Pure Encapsulations cost $32.60 for 180 capsules, targeting people who need hypoallergenic, pharmaceutical-grade ingredients.

   Vital Nutrients Glycine Powder is available at $34.90 for 250 grams of powder, making it the least cost-effective powder, leaning more toward practitioner use than budget-conscious consumers.

Frequently Asked Questions

1. Are there any natural sources of glycine in food?
   Yes, glycine is found in high-protein foods like meat, fish, dairy, legumes, and bone broth.
2. Is there a difference between glycine and L-glycine in supplements?
   No, L-glycine is a naturally occurring form found in the human body and supplements. The “L” simply refers to its molecular orientation.
3. Can glycine supplements help with sleep issues?
   Taking glycine products may help improve your sleep quality by lowering body temperature and calming your nervous system. However, results may vary by person.

Conclusion

Glycine supplements could help support sleep, regulate metabolism, and produce collagen. They could also help manage stress and improve sleep quality. The supplements featured in this blog offer a variety of options that may suit different needs, whether you prefer capsules for convenience, powders for flexible dosing, or allergen-free formulas for sensitivity.

Some focus on sleep and cognitive support, while others target blood sugar balance or liver function. However, glycine supplements aren’t always necessary. These supplements could also trigger side effects like nausea, bloating, or loose stools, especially when taken without food.

Taking foods like bone broth, gelatin, turkey, chicken skin, eggs, and legumes can also boost your glycine levels naturally. These glycine supplements might help increase overall intake if dietary sources are limited, but they’re not always necessary. You could consider combining both approaches depending on your needs. It’s best to talk with a doctor to determine what’s appropriate for your diet and goals.