The Best L-Glutamine Supplements, According to Registered Dietitians

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WITH ALL THE supplements on the market promising to make you stronger, faster, and healthier, you may have come across L-glutamine and wondered if it’s worth the hype. Often sold as a sports supplement, this amino acid has many potential benefits, but only if you actually need it.

“L-glutamine is considered a 'conditionally essential' amino acid, which means your body normally makes enough of it to support its needs,” says registered dietician Kristin Draayer, RDN, CPT. Glutamine is essential for immune cell function and affects muscle recovery and gut health. For most healthy adults, eating a balanced diet with adequate protein is enough to supply and produce all the glutamine your body needs.

Best L-glutamine Supplement

“Glutamine helps your immune system function, though supplementation only truly seems to be helpful when people have very low protein intakes or when the immune system is highly stressed, such as from major infection, major surgery, burns, or certain forms of radiation,” says registered dietician Brian St. Pierre, MS, RD, CSCS, the Director of Performance Nutrition at Precision Nutrition.

While glutamine supplementation is frequently prescribed by healthcare professionals for people with high-level medical needs, it’s also frequently marketed as a supplement to aid in athletic performance or to improve and support a healthy gut.

While there’s currently no evidence that glutamine supplementation can improve athletic performance, few studies have shown that it may enhance strength recovery and decrease muscle soreness in men, says Draayer. More research is needed, as the results are not consistent.

This amino acid also plays an important role in gut health and supplementing could benefit some athletes. “Glutamine could support gastrointestinal integrity during long periods of endurance exercise, potentially reducing the risk of illness after extended endurance activity,” says Draayer, although once again, more quality research is needed.

While experts agree that most healthy people won’t see a benefit from taking L-glutamine supplements, there is the potential for some benefits for those who regularly put their bodies under maximum stress with activities such as marathons or Iron Man training. “Glutamine is likely safe for most healthy adults at doses under 40 grams per day. So, there likely is no harm in supplementing if you have the financial means to do so,” says Draayer.

What to Consider

Dose

There is not a universally accepted dose for glutamine supplementation, and excessive doses could lead to a buildup of ammonia in the body. “The appropriate dosage depends on your individual needs and why you're taking it. It's always best to consult with a doctor or dietitian before starting any new supplement to determine the right dosage for you,” says Draayer. Most L-glutamine supplements are sold in 1 to 5-gram doses.

Form

Glutamine supplements are available in capsules and liquids, but the most common form you’ll find is powder, which can then be mixed with water before taking. “The best form comes down to preference and affordability,” advises Draayer.

Certifications and Quality

One of the most important factors to consider when choosing an L-glutamine supplement is the quality. Supplements are not regulated by the FDA, so trusting that what the package says is exactly what it contains is crucial for safety and effectiveness. Look for third-party verification certifications on the label, such as USP, NSF, or Informed Choice Certified.

How We Selected

To find the best L-glutamine supplements available, we spoke to the experts and reviewed a dozen popular supplements. We checked for third-party verification, ingredients, dose, certifications, price, and reviews. All of the products on our list have third-party verification and certifications by either USP, NSF, or Informed Choice to assure purity and potency. Keep reading to find the best L-glutamine supplement for your needs.

L-Glutamine

“One of my favorite L glutamine powder products is from Thorne. I love this as it's NSF Certified, and it’s easy to dissolve in a liquid,” says Nicole Ibarra, RD, LD, a registered dietitian and author specializing in Sports Nutrition and Fitness.

Thorne has a reputation for quality, and their L-glutamine powder follows suit. With third-party verifications ensure it’s free from substances banned for athletes, there’s an extra layer of assurance when adding this to your routine.

The powder is unflavored and tasteless, and while you can mix it with water, many people combine it with other supplements like protein or creatine to make the most of their beverage. Each container has ninety 5-gram servings, and you can save an extra 20% on your order by choosing the subscribe and save option.

Read more: Best Multivitamins for Men

L-Glutamine

For a budget-friendly option that’s still top quality, try Momentous L-glutamine powder. Each serving has 5 grams of glutamine in an unflavored powder that mixes with water or your morning smoothie.

The pure L-glutamine powder has no sweeteners, colors, or other additives and is vegan and free from soy and gluten.

Unlike many other glutamine supplements, Momentous comes in a resealable bag. While this will take up less space in your pantry, it can be difficult to scoop the last few servings out, and if powder gets on the seal, hard to fully close.

You’ll get 60 servings in each bag, costing just $0.64 per serving. You can save even more by choosing a subscribe and save option, bringing the cost down to as low as $0.51 per serving.

BCAA Sport Hydration Powder

If you’re using L-glutamine to assist with muscle recovery, Cellucor BCAA Sport Hydration Powder adds the power of branched-chain amino acids and electrolytes to glutamine to help you recover from tough workouts.

Each serving of this recovery powder has 8.25 grams of amino acids plus 2 grams to glutamine. Some research has found that supplementing with branched-chain amino acids can help reduce muscle soreness after exercise. You’ll also get 110 miligrams of sodium and 172 milligrams of chloride to replace a small amount of electrolytes as you hydrate. It’s also NSF-Certified for Sport, so you know it’s free from any banned substances.

The powder mixes well with water or juice, although some people report an artificial taste, most likely because of the artificial sweeteners. You can find this supplement at any major grocery store or online.

Glutamine

“L-glutamine helps to keep the gut lining's tight junctions intact, which can help reduce risk of leaky gut, and helps to reduce pro-inflammtory pathways,” says Ibarra. Whether you’re using it to ease sore muscles, strengthen your immune system, or support a healthy gut, MusclePharm Glutamine has 5 grams of L-glutamine in each serving at a budget-friendly price.

This powder mixes well with water by itself or when combined with protein powder and is Informed Choice Certified, so you know you’re getting what the package says and nothing else. It’s by far one of the lowest-costing glutamine supplements and still high quality with testing and certifications behind it.

Glutamine

Each container of Klean Glutamine contains ninety 5-gram servings of L-glutamine. This unflavored, fine powder is free from artificial flavors, sweeteners, or additives, so you know you’re only adding glutamine to your diet. As an NSF-Certified for Sport supplement, you can also rest assured that it’s free from any banned substances.

While this supplement mixes well with any liquid, you can use it as a companion to other supplements like protein powder or creatine, both of which can also help with muscle repair and recovery, independent of glutamine status.

Meet the Experts

• Brian St. Pierre, MS, RD, CSCS, CISSN, Pn1, is the Director of Performance Nutrition at Precision Nutrition.

• Kristin Draayer, MS, RDN, CPT, is a registered dietitian and certified personal trainer at Kristen Draayer Nutrition and Fitness.

• Nicole Ibarra, RD, LD, is a registered dietitian and author specializing in Sports Nutrition and Fitness.

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