Save to favorites
This feature is restricted to active members.
Join now to save favorites and get all member benefits, including over 1,400 reviews.
Join NowAlready a member? Sign in here.
Best L-Glutamine Supplements According to ConsumerLab Tests
White Plains, NY, March 13, 2025 — L-glutamine (glutamine) supplements are promoted to boost energy and the immune system and for other benefits, but do they really work, and if so, which glutamine products on the market are best?
To identify the best products, ConsumerLab recently purchased and tested seven popular L-glutamine powders and capsules, checking if they contained their expected amounts of glutamine. Products containing whole herbs or significant amounts of minerals were tested for contamination with the toxic heavy metals lead, arsenic, cadmium, and mercury.
The L-Glutamine Supplements Review includes test results and comparisons for seven L-glutamine supplements selected for testing by ConsumerLab: BulkSupplements.com L-Glutamine, NOW L-Glutamine 500 mg, NOW Sports L-Glutamine Powder, Nutricost L-Glutamine - Unflavored, Pure Encapsulations L-Glutamine 500 mg, Swanson L-Glutamine Powder, and Thorne L-Glutamine Powder.
As explained in the Review, L-glutamine is an amino acid produced in the body that is involved in cellular energy production, and in maintaining muscle cells, the immune system, and the digestive tract. Although it's not necessary to get glutamine from the diet, there is some evidence that taking large doses of glutamine as a supplement may reduce infections after over-training, reduce symptoms of irritable bowel syndrome after infections, and reduce mouth irritation due to chemotherapy. The evidence for this uses is discussed, as well as what to look for on product labels, whether it’s worth paying more for “free-form” glutamine, the best way to store glutamine powders and capsules, and safety and side effects with glutamine supplements.
Founded in 1999, ConsumerLab.com is a leading provider of consumer information and independent evaluations of products that affect health and nutrition. It has reviewed over 7,000 products and has published Product Reviews covering nearly every popular category of dietary supplements and health foods.
Membership to ConsumerLab.com is available online and provides immediate access to continually updated reviews of nearly every popular type of dietary supplement and health food, answers to reader questions, and product recalls and warnings. ConsumerLab also provides independent product testing through its voluntary Quality Certification Program. The company is privately held and based in New York. It has no ownership from, or interest in, companies that manufacture, distribute, or sell consumer products.
To identify the best products, ConsumerLab recently purchased and tested seven popular L-glutamine powders and capsules, checking if they contained their expected amounts of glutamine. Products containing whole herbs or significant amounts of minerals were tested for contamination with the toxic heavy metals lead, arsenic, cadmium, and mercury.
Key Findings:
- Most products were of high quality: All seven of the L-glutamine powders and capsules selected for testing by ConsumerLab.com were found to contain their listed amounts of glutamine within a reasonable margin of error (90% to 110% of claim).
- Price does not indicate quality: The cost to obtain a 1,000-mg dose of glutamine from the tested products ranged from 4 cents to more than 50 cents but testing showed that price was not an indicator of quality, and the least expensive way to get L-glutamine is from powders, which can be mixed in water or other beverage – although it should be consumed soon after it’s prepared.
Access the Full Report:
ConsumerLab’s full L-Glutamine Supplements Review can now be accessed online by ConsumerLab.com members – who now number over 100,000.The L-Glutamine Supplements Review includes test results and comparisons for seven L-glutamine supplements selected for testing by ConsumerLab: BulkSupplements.com L-Glutamine, NOW L-Glutamine 500 mg, NOW Sports L-Glutamine Powder, Nutricost L-Glutamine - Unflavored, Pure Encapsulations L-Glutamine 500 mg, Swanson L-Glutamine Powder, and Thorne L-Glutamine Powder.
As explained in the Review, L-glutamine is an amino acid produced in the body that is involved in cellular energy production, and in maintaining muscle cells, the immune system, and the digestive tract. Although it's not necessary to get glutamine from the diet, there is some evidence that taking large doses of glutamine as a supplement may reduce infections after over-training, reduce symptoms of irritable bowel syndrome after infections, and reduce mouth irritation due to chemotherapy. The evidence for this uses is discussed, as well as what to look for on product labels, whether it’s worth paying more for “free-form” glutamine, the best way to store glutamine powders and capsules, and safety and side effects with glutamine supplements.
Founded in 1999, ConsumerLab.com is a leading provider of consumer information and independent evaluations of products that affect health and nutrition. It has reviewed over 7,000 products and has published Product Reviews covering nearly every popular category of dietary supplements and health foods.
Membership to ConsumerLab.com is available online and provides immediate access to continually updated reviews of nearly every popular type of dietary supplement and health food, answers to reader questions, and product recalls and warnings. ConsumerLab also provides independent product testing through its voluntary Quality Certification Program. The company is privately held and based in New York. It has no ownership from, or interest in, companies that manufacture, distribute, or sell consumer products.
— END —
Members of the media contact may contact media@consumerlab.com or call the ConsumerLab.com main number (914-722-9149). Please include the name of your news organization when contacting us.
