Best Glutamine Supplement

Discover if a supplement of the body’s most abundant amino acid can improve exercise, immunity, gut health, or weight loss.

Last updated: Dec 23rd, 2022
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In this Review

Summary of recommendations
Glutamine supplements: top considerations
How our top recommendations compare
What is glutamine?
How glutamine supplements work
Are glutamine supplements a good choice for you?
Are glutamine supplements safe?
Onnit L-Glutamine Amino Acid Powder
Nutricost L-Glutamine Powder
Transparent Labs BCAA Glutamine Powder
Thorne L-Glutamine Capsules
Bulk Supplements N-Acetyl L-Glutamine Powder
Glutamine supplement FAQ
Why you should trust us
Best Glutamine Supplement

Dietary supplements are incredibly popular, and many people are searching for a supplement that can contribute to their overall health. Some supplements can seemingly do it all; they support many body processes and help you meet your long-term health goals.

Supplements that contain glutamine (sometimes shown as L-glutamine) may seem too good to be true. This potent amino acid helps your body synthesize protein and may help you build muscle, recover faster from exercise, boost your immune system, improve your gut health, and speed up weight loss. Scientific research shows that many of these claims are accurate, while some still require more research.

Our guide breaks down the features of glutamine supplements and provides our top picks based on cost, quality, and effectiveness. Keep reading to discover if a glutamine supplement is right for your health journey.

If you’re in a hurry, check out our top 5 recommendations below.

Summary of recommendations

Our Top Picks
Onnit L-Glutamine Amino Acid Powder logo

Onnit L-Glutamine Powder is an effective, quality product available at an affordable price.

Onnit’s powder contains pure L-glutamine for elevated performance, endurance, and muscle building. It’s vegan-friendly, safety certified, and backed by a 90-day money-back guarantee.

Glutamine supplements: top considerations

We use five essential criteria to evaluate our top picks: cost, ingredients, effectiveness, safety, and convenience. Below, see how our top five recommendations perform to help you get a comprehensive view of each product.


Winner: Bulk Supplements

When we evaluate the cost of a glutamine supplement, we look at more than just the price. We also consider the product’s value based on any money-saving opportunities, subscription options, and bulk purchase discounts. Money-back guarantees and shipping costs play a role in our decisions too.

Our winner in this category is Bulk Supplements because they offer the cheapest product in this guide, hands down. You can purchase a 100g bag of glutamine powder, which contains 200 servings, for only $13.96. This equates to a little more than $0.07 per serving, by far the lowest per serving price in this guide. In addition, Bulk Supplements also provides a 30-day money-back guarantee and free shipping on orders over $59. If you choose a subscription option, you’ll save 5% on your entire order. All of these cost-cutting features combined make Bulk Supplements our budget-friendly pick.


Winners: Transparent Labs and Onnit

An effective glutamine supplement should contain a healthy amount of glutamine and perhaps a few other standout ingredients that support this main element. Or you may prefer a supplement that is just pure glutamine. Either way, the ingredients in a glutamine supplement should serve the supplement’s intended purpose, and the company should provide detailed info about what’s contained in the product.

The products in this guide with standout ingredients are Transparent Labs and Onnit, but for very different reasons. Transparent Labs’ product includes a mix of ingredients that increase the effectiveness of glutamine and enhance the supplement’s health outcomes. It contains leucine, isoleucine, and valine, which are branched-chain amino acids (BCAAs) that help with exercise endurance and muscle growth. The supplement also contains vitamin C to enhance immune function and coconut water powder for increased electrolyte intake so you stay hydrated while you’re building more muscle.

Onnit L-Glutamine Amino Acid Powder is also a winner in this category for the opposite reason — it contains pure glutamine and nothing else. It’s an unflavored powder that mixes well with any beverage and provides a glutamine boost to help with gut health, immunity, and muscle recovery. It’s also dairy- and soy-free.


Winner: Onnit

We judge a product’s effectiveness based on its health claims and what it actually delivers. It’s important to know that the product is backed up by scientific research and that you can reap the benefits of its formula. This can be hard to determine when dealing with a substance like glutamine because clinical trials about muscle building and weight loss have been inconclusive. However, your best bet is to choose a product that delivers glutamine without other distracting elements, ensuring you’re getting what you pay for.

Onnit wins in this category because of the simplicity of its formula. Unlike many other glutamine supplements, Onnit’s powder contains no other ingredients and provides you with a pure dose of glutamine in every scoop. If you want a product that doesn’t include fillers, additives, or other unnecessary elements, Onnit is the right choice for you.


Winner: Nutricost

When taking any dietary supplement, it’s essential to pay attention to the steps the company takes to ensure their product is safe. Since the FDA does not regulate supplements the same way as food and prescription drugs, it’s important to consider a company’s manufacturing, storage, testing, and shipping practices to ensure you’re buying a pure product. Most supplement companies are transparent about these processes and include details on their websites.

Our winner in this category is Nutricost. Their glutamine supplement is third-party tested. This means that it is thoroughly checked without bias to ensure it meets high quality and purity standards. The company also manufactures their products in a GMP-compliant facility registered with the FDA. When a company takes this many steps to ensure a product’s safety, you can rest assured that you’re getting a quality product.


Winner: Thorne

Remembering to consistently take a dietary supplement can be difficult, especially if the supplement has complicated dosing instructions. It’s vital to look for a supplement that can easily fit into your daily routine so that you can be consistent and achieve the best results.

Our winner for convenience is Thorne because of their capsule’s flexible dosing instructions. Each capsule includes just 500mg of glutamine (much less than the powder formulas in this guide that suggest serving sizes between 5g and 19g daily). Because the per capsule dose is so low, you can determine how many capsules you take per day, with the company suggesting up to three. This flexibility makes it easier to introduce this product into your routine. (If you don’t like swallowing pills, you can opt for Thorne’s powder version of the same supplement.)

How our top recommendations compare

What is glutamine?

Glutamine is an amino acid found in the body that aids in synthesizing proteins. Proteins are the building blocks of the body. They help keep organs functioning and help the body fight off infection, among other things that keep us alive. Glutamine is naturally found in the body, but it’s also found in foods and dietary supplements. Sometimes, glutamine supplementation is prescribed for those undergoing chemotherapy or recovering from surgery.

You may notice that there are two forms of glutamine: L-glutamine and D-glutamine. D-glutamine is not essential to body processes, so you’ll often see supplements that include L-glutamine, the form humans need for overall health. L-glutamine is the bioavailable form, meaning that it’s the kind that we can digest and use most easily. Often it is just referred to as glutamine.

In addition to helping with recovery from illness or injury, glutamine may also help with other body processes, including:

  • Building muscle
  • Reducing exercise recovery time
  • Supporting immunity
  • Enhancing intestinal health
  • Promoting weight loss

While glutamine’s importance to immunity and intestinal health has been shown by scientific research, more research must be done to affirm its role in muscle building and weight management. Nonetheless, it’s a popular pre- and post-workout supplement ingredient.

You can also obtain glutamine from a balanced diet, particularly foods high in protein. Here are some foods that contain glutamine:

  • Eggs
  • Beef
  • Skim milk
  • Tofu
  • White rice
  • Corn

There is no specific amount of glutamine that you should ingest per day, mainly because it’s an amino acid that your body already naturally produces. However, some clinical studies have noted doses between 5-45g per day without severe side effects. Essentially, the amount of glutamine you take daily depends on your desired outcome, the product’s serving suggestions, and your doctor’s recommendations.

Glutamine has nothing to do with gluten, so those who live with celiac disease or maintain a gluten-free diet are in the clear. Just be sure to make sure the supplement you choose is completely gluten-free, as there may be ingredients in addition to glutamine that do contain gluten.

How glutamine supplements work

Glutamine supplements work by boosting your body’s glutamine levels and helping it synthesize proteins more effectively. This can accelerate muscle and tissue repair and fight illness and infections. Other fitness-related uses for glutamine include muscle building, exercise recovery, and weight loss. While these claims require more clinical research, preliminary studies reveal promising results.

Read on to discover how glutamine supplements can improve your overall health.


Glutamine can help boost the immune system. There is a wealth of research that’s been conducted to show this link, but we’ve highlighted some important ones below:

  • One review found that glutamine is a crucial immunonutrient that can help people recovering from illness or injury recover faster.
  • This review shows that patients recovering from bone marrow transplants who were given glutamine-supplemented diets experienced lower levels of infection than patients who ate a standard diet.
  • This clinical trial found that administering a glutamine-enriched diet to patients after abdominal surgery lowered incidences of infection and shortened hospital stays.
  • Several animal studies show that glutamine boosts the immunity of virus-infected animals.

Intestinal health

Glutamine can help boost your intestinal health, particularly addressing issues stemming from a leaky gut. Since intestinal health is linked to immunity, quieting a leaky gut is another way that glutamine can support your immune health.

This review found that glutamine helps protect and repair the gut when it's under stress, while another found that glutamine can help with IBS and intestinal permeability (the clinical term for leaky gut). Another review found that low glutamine levels are linked to intestinal barrier deterioration.

Muscles and exercise

Glutamine is a popular ingredient in pre- and post-workout supplements. It’s easy to assume that glutamine facilitates muscle building because it helps synthesize protein. However, clinical testing of this hypothesis has not supported it. For example, in one trial, participants took glutamine supplements for six weeks while weight training and showed no significant muscle gain or performance. Other similar studies have shown comparable results.

On the other hand, some clinical trials have shown that glutamine supplementation can help reduce muscle soreness after exercise, potentially leading to improved exercise recovery. For example, one trial showed that male participants experienced improved muscle recovery and soreness after supplementing with glutamine and performing knee extensions.

Weight loss

As with muscle building, glutamine’s effect on weight loss is still inconclusive and requires more testing. However, some studies have shown encouraging results. One trial involving obese female patients found that supplementing with glutamine for four weeks led to lower waist circumference and body weight. However, another study found that supplementing with glutamine did not affect body composition.

Are glutamine supplements a good choice for you?

Glutamine supplements may be a good choice if you’re interested in boosting your immunity or intestinal health. It could also be a good option if you’re recovering from an injury, illness, infection, or other condition that depletes your body’s natural ability to produce glutamine.

For example, glutamine supplementation is often used to help those living with cancer. Glutamine supplementation can lessen one of the severe side effects of chemotherapy called mucositis, which affects the intestines and causes throat and mouth sores. If you’re experiencing these symptoms, talk to your doctor about glutamine supplementation.

Glutamine supplements may also be a good choice if you are interested in building muscle, speeding up exercise recovery, or losing weight. Even though clinical research about glutamine’s impacts is inconclusive, user testimonials of many glutamine-based products indicate that they are effective as pre- and post-workout supplements.

Who should avoid them

Some health conditions may be exacerbated by glutamine supplementation. It’s important to talk to your doctor before beginning any new supplement, as they have the best knowledge of any potential contraindications. Still, if you are living with any of the following conditions, it’s best to avoid added glutamine:

  • Kidney disease
  • Liver disease
  • Reye’s syndrome
  • Seizure disorder
  • Psychiatric disorders

This supplement can also interact with some medications, like lactulose. Even though some trials have shown that glutamine supplementation can help with chemotherapy side effects, other clinical research shows that it may increase tumor production. If you’re living with cancer, talk to your doctor about whether glutamine is safe for you.

If you are elderly, you should reduce your intake of daily glutamine. You should also avoid glutamine supplements if you are pregnant or breastfeeding. Although glutamine supplementation has been used to care for infants and children, consult with a pediatrician before giving them to anyone under age 18.

Are glutamine supplements safe?

Glutamine supplements are generally safe to take for most healthy adults. Be aware that some people are allergic to glutamine and may experience side effects like:

  • Nausea
  • Vomiting
  • Joint pain
  • Hives

If you experience these symptoms after taking a glutamine supplement, seek immediate medical attention and discontinue use.

Daily intake of a glutamine supplement can also result in some mild side effects like bloating, dizziness, upset stomach, or heartburn. If you experience these, lower your dosage or consider stopping supplement use.

The jury is still out concerning the safety of taking glutamine supplements long-term. Most clinical studies administer the supplement for only a few weeks, so we do know that short-term use is safe up to about 45g per day, with 5g per day being a more sustainable amount. Since more research needs to be done about the long-term effects, it’s important to stay informed about scientific developments as they happen if you plan to take glutamine for longer than a few weeks.

Onnit L-Glutamine Amino Acid Powder

Best for most people and best powder


  • Pure L-glutamine formula with no added ingredients

  • Affordable price

  • Informed Sport-certified

  • May help improve digestion, reaction time, and exercise endurance

  • Vegan-friendly

  • 90-day money-back guarantee

  • Subscribe and save 15%


  • Unflavored option only

  • You must spend $150 to earn free shipping

Onnit’s L-Glutamine Amino Acid Powder is our overall top choice and pick for best powder because of the product’s straightforward delivery system, affordable price, and safety certifications. This unflavored powder contains L-glutamine and no other active ingredients, ensuring you get a pure dose of this potent amino acid. You can also purchase a 60-day supply for only $21.99, with added discounts for a subscription order. Onnit’s supplement is Informed Sport-certified, meaning that it’s free from banned substances and safe to use by competitive athletes.

In addition to these impressive features, Onnit’s glutamine powder also boasts an outstanding list of potential health benefits. Taking this powder can lead to:

  • Improved aerobic performance
  • Better digestion for a healthy gut
  • Shortened reaction time
  • Increased muscle building
  • Enhanced exercise endurance
  • Improved nutrient absorption

Because it’s unflavored, the powder mixes well with any beverage without altering the flavor. Take one scoop (5g) with eight ounces of liquid daily for best results. The supplement is free from dairy and soy and is vegan-friendly.


A 60-serving tub of Onnit’s glutamine supplement costs $21.99 to purchase once. You can opt for a subscription to save 15% ($18.69/tub). Your order will auto-ship every 7-90 days, depending on your preference. Onnit offers free shipping on orders over $150.

Onnit’s Keep-It guarantee covers all first-time orders. This guarantee allows 90 days to initiate a potential refund if you’re unsatisfied with the product. Instead of returning the product to Onnit, you get to keep whatever’s left and still receive a refund. However, you’ll need to try out the product for at least two weeks before initiating a refund.

Nutricost L-Glutamine Powder

Best for weight loss


  • Offers unflavored, blue raspberry, and fruit punch flavors

  • Gluten- and GMO-free

  • Vegetarian-friendly

  • Includes a serving-sized scoop

  • Third-party tested and GMP-compliant

  • 60-day money-back guarantee


  • No option to subscribe and save

  • Website does not include many product details

While there are no glutamine supplements designed specifically for weight loss, we chose Nutricost’s L-Glutamine Powder as our top weight loss pick because of its formulation and flavor options. This powder provides 5g of glutamine per serving, and the unflavored option includes no other ingredients. This makes it a low-calorie option that you could add to any healthy beverage. The flavored options (blue raspberry and fruit punch) offer a tasty accent to water or any other liquid without a lot of added sugar. The supplement is also gluten-free, non-GMO, and vegetarian-friendly.

You can choose from three size options: 250g, 500g, or 1kg. Your order of powder includes a scoop that measures out one serving (5g). Mix one scoop with 6-10oz of liquid daily.

The supplement is third-party tested for quality and purity. It’s also manufactured in a GMP-compliant facility registered with the FDA.


Nutricost offers free shipping on orders over $59 placed in the contiguous U.S. and covers each order with a 60-day money-back guarantee (minus shipping costs).

The company does not offer a subscription option, but the price breakdown of each bottle size is outlined below.

Transparent Labs BCAA Glutamine Powder

Best muscle builder


  • Contains BCAAs for increased muscle building

  • Includes vitamin C for enhanced immunity

  • Coconut water powder provides a hydration boost

  • Choose from five delicious flavors

  • Vegan-friendly with no artificial ingredients

  • 30-day return policy

  • Subscribe and save 15%


  • Contains stevia for added sweetness

  • Serving size may be too much for some

Transparent Labs BCAA Glutamine Powder is our top muscle builder because it boosts your muscle-building potential by combining the power of glutamine with BCAAs. In addition to glutamine, this supplement also contains leucine, isoleucine, and valine — the BCAAs known for growing muscle and enhancing exercise performance. In addition to glutamine and BCAAs, the supplement also includes coconut water powder that helps with hydration and electrolyte balance, as well as vitamin C, which can help boost immunity.

Transparent Labs is committed to putting out products that include pure and clean ingredients and providing comprehensive ingredient lists to consumers (hence the company’s name). Because of this, their glutamine supplement is vegan-friendly and does not contain:

  • Dyes
  • Fillers
  • Additives
  • Artificial sweeteners
  • Preservatives

This tasty powder is ideal for drinking before and during workouts, and each serving includes 19.18g of powder, much larger than the 5g per serving of most glutamine powders. However, you’re still only getting 5g of glutamine per serving. The rest of the 19.18g serving is added ingredients.

Transparent Lab’s supplement provides more flavor options than any other product on this list:

  • Sour green apple
  • Tropical punch
  • Strawberry lemonade
  • Blue raspberry
  • Orange


One tub of powder costs $39.99, which includes a 30-day supply. You can earn free shipping by placing an order over $99. Joining Transparent Labs’ subscription program saves you 15% ($33.99/tub) and unlocks free shipping. Choose to have your order auto-shipped every 30 or 45 days.

Transparent Labs offer a 30-day return policy on unopened products for a full refund. If your product is opened, you can still return it within 30 days for a store credit or product exchange.

Thorne L-Glutamine Capsules

Best capsules


  • Low dose per capsule (500mg) makes for flexible dosing

  • May help with muscle cell repair

  • Receive 90 capsules per bottle

  • Gluten-, dairy-, and soy-free

  • 60-day money-back guarantee

  • Subscribe and save 10%


  • Not ideal if you can’t swallow pills

  • 500mg/capsule not ideal for those who need a high dose

We chose Thorne L-Glutamine Capsules as our top capsule pick because their product provides a low-level dose of glutamine that you can control by adjusting the number of capsules you take per day. Each capsule includes only 500mg of glutamine (and not much else), and you can take between one and three per day, depending on your preference or doctor’s recommendations. This is a much more mild dose than many other products that offer 5g of glutamine per serving.

In addition to flexible dosing, these capsules may help with a variety of body processes, including:

  • Muscle cell repair
  • Gastrointestinal health
  • Immunity
  • Healing after exercise, injury, or surgery

Thorne’s formula only contains natural colors and flavors and is free from gluten, dairy, and soy.


Each bottle of Thorne costs $21 for 90 capsules. You can choose to subscribe and save 10% on each subsequent auto-refill order and take advantage of free shipping. If you subscribe to three or more Thorne products, you’ll save 20%. Choose a delivery interval of one, two, three, or four months.

A 60-day money-back guarantee covers all orders. If you’re unsatisfied with a product, return it for a refund, credit, or replacement.

Bulk Supplements N-Acetyl L-Glutamine Powder

Best budget pick


  • Pay as little as $0.07 per serving

  • Choose from six product sizes — up to 25kg of powder

  • Free shipping on orders over $59 in the contiguous U.S.

  • May help with exercise endurance and recovery

  • Works as a pre-workout supplement

  • 30-day return policy

  • Subscribe and save 5%


  • Each serving is 500mg, which may be low for some customers

  • Subscription does not provide free shipping

Bulk Supplements N-Acetyl L-Glutamine Powder is our best budget pick because the company offers the cheapest per serving price of the products mentioned in this guide (at $0.07/serving). Bulk Supplements also provides the most sizing and pricing options, a 30-day money-back guarantee, a subscription option to save 5%, and free shipping on orders over $59. When you combine these money-saving features with Bulk Supplements’ bulk purchase options, they simply can’t be beat when it comes to value.

In addition to being budget-friendly, this powder also offers many health benefits. It includes the N-acetyl form of glutamine, which has a bigger role in protein synthesis than L-glutamine. This product may:

  • Increase athletic endurance
  • Enhance pre-workout
  • Speed exercise recovery
  • Boost immune and metabolic functions
  • Support digestive health

The powder does not contain added sugar, soy, dairy, yeast, gluten, or other additives. Each serving provides 500mg of glutamine powder. For best results, take up to three servings per day on an empty stomach.


A one-time purchase of a 100g-bag of powder costs $13.96. You can also opt for a subscription purchase and save 5%. Bulk Supplements live up to their name and offer product sizes up to 25kg of powder. The chart below breaks down the prices.

If you choose to join their subscription program, your order will auto-ship every 30, 60, or 90 days. Bulk Supplements provides free shipping on orders over $59 placed in the contiguous U.S. and covers orders with a 30-day return policy. Return unopened products for a full refund and opened products for a partial refund.

Glutamine supplement FAQ

Why you should trust us

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Additionally, like all health-related content on this website, this review was thoroughly vetted by one or more members of our Medical Review Board for accuracy.