Best L-Glutamine Supplements 2026: Cost per Effective Dose
Top pick for L-Glutamine: Naked Nutrition Pure L-Glutamine Powder (1 kg, 200 servings) — 5000mg L-glutamine per 1 scoop (5 g), None (3rd-party heavy-metal tested), $0.17/day. Our best-value pick.
Registry check · L-Glutamine
Does anyone independently verify L-Glutamine supplements?
Not one of these 14 products is listed by NSF, USP or Informed Sport as a verified product. Yet 4 of them advertise “third-party testing” without naming the certifier that did it — wording no public registry can confirm or deny. 2 display a named mark we could not find in the matching registry. A factory-level claim such as “cGMP” audits the plant, not the L-Glutamine bottle you would actually receive.
14 checked against all 5,317 US NSF, USP and Informed Sport listings, 2026-08-25. Full method and limitations.
What 13 L-Glutamine labels show
Priced per day, these L-glutamine products run $0.06 to $0.74 — a 12× gap between the cheapest and dearest L-glutamine here, across 10 brands.
Which row that favours is not obvious: Horbaach Horbaach L-Glutamine 1000 mg (180 Capsules) is cheapest per serving at $0.06, but its serving sits below the median here, so part of that price gap is simply a smaller capsule.
All L-Glutamine Supplements Compared
| Product | Brand | Dose / Serving | Cost / Day | Certification (as labelled) | Pick | Buy |
|---|---|---|---|---|---|---|
| Horbaach L-Glutamine 1000 mg (180 Capsules) | Horbaach | 1000mg L-glutamine / 1 capsule (1 g) | $0.06 | None | Buy | |
| Optimum Nutrition L-Glutamine 1000 mg (240 Capsules) | Optimum Nutrition | 1000mg L-glutamine / 1 capsule (1 g) | $0.08 | None | Buy | |
| NOW Sports L-Glutamine 1000 mg (120 Veg Capsules) | NOW Foods | 1000mg L-glutamine / 1 capsule (1 g) | $0.13 | None (cGMP) | Buy | |
| Naked Nutrition Pure L-Glutamine Powder (1 kg, 200 servings) | Naked Nutrition | 5000mg L-glutamine / 1 scoop (5 g) | $0.17 | None (3rd-party heavy-metal tested) | Best Value | Buy |
| BulkSupplements L-Glutamine Powder (1 kg) | BulkSupplements | 5000mg L-glutamine / 1 scoop (5 g) | $0.18 | None (3rd-party tested) | Buy | |
| Nutricost L-Glutamine Powder (500 g) | Nutricost | 5000mg L-glutamine / 1 scoop (5 g) | $0.23 | None (3rd-party tested) | Buy | |
| Sports Research L-Glutamine Powder (500 g) | Sports Research | 5000mg L-glutamine / 1 scoop (5 g) | $0.25 | None (NOT NSF Certified for Sport despite sport branding) | Buy | |
| BulkSupplements L-Glutamine Powder (500 g) | BulkSupplements | 5000mg L-glutamine / 1 scoop (5 g) | $0.25 | None (3rd-party tested) | Buy | |
| NOW Sports L-Glutamine Pure Powder (1 lb) | NOW Foods | 5000mg L-glutamine / 1 rounded tsp (5 g) | $0.27 | None (cGMP) | Buy | |
| MRM L-Glutamine 5000 mg Powder (500 g) | MRM Nutrition | 5000mg L-glutamine / 1 scoop (5 g) | $0.27 | None | Buy | |
| Optimum Nutrition L-Glutamine Powder (1000 g) | Optimum Nutrition | 5000mg L-glutamine / 1 scoop (5 g) | $0.29 | None (NOT NSF Certified for Sport) | Buy | |
| Life Extension L-Glutamine Powder (100 g) | Life Extension | 2000mg L-glutamine / 1/2 tsp (2 g) | $0.33 | None | Buy | |
| Thorne L-Glutamine Powder (513 g, 90 servings) | Thorne | 5000mg L-glutamine / 1 scoop (5 g) | $0.74 | NSF Certified for Sport | Buy |
Our Picks
Best Value: Naked Nutrition Pure L-Glutamine Powder (1 kg, 200 servings)
5000mg L-glutamine per 1 scoop (5 g). None (3rd-party heavy-metal tested). $0.17/day. 200 servings per container at $34.99.
Naked Nutrition Pure L-Glutamine Powder (1 kg, 200 servings) →
The shelf · L-Glutamine
These L-Glutamine servings are not comparable to each other
Horbaach L-Glutamine 1000 mg (180 Capsules) states 1,000 mg a serving and Thorne L-Glutamine Powder (513 g, 90 servings) states 5,000 mg — both occupy one row of the same price column. So Horbaach L-Glutamine 1000 mg (180 Capsules) showing 6¢ a day, the lowest here, may be reporting a smaller serving rather than a better price. Before comparing Horbaach L-Glutamine 1000 mg (180 Capsules) with Thorne L-Glutamine Powder (513 g, 90 servings), check what each calls a serving.
Method: the 14 L-Glutamine products above, compared on label facts — serving size, servings per container, form, price. Not a dosing recommendation.
The evidence · L-Glutamine
What the published reviews of L-Glutamine concluded
- A Phase 3 Trial of l-Glutamine in Sickle Cell Disease. · The New England journal of medicine, 2018
“Among children and adults with sickle cell anemia, the median number of pain crises over 48 weeks was lower among those who received oral therapy with l-glutamine, administered alone or with hydroxyurea, than among those who received placebo, with or without hydroxyurea.”
- L-arginine vs. L-glutamine oral suspensions for radiation-induced oral mucositis: a triple-blind randomized trial. · Journal of cancer research and clinical oncology, 2025
“Both L-arginine and glutamine significantly reduced RIOM severity, pain, and weight loss compared to maltodextrin, while improving quality of life in patients with head and neck cancer.”
- Effects of L-glutamine and hyaluronic acid associated with photobiomodulation on oral mucositis: a randomized clinical trial. · Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer, 2025
“The combination of PBM + POCP + L-G + HA resulted in a significantly lower severity of OM than PBM + POCP alone, according to the WHO scale at the 30th RT.”
- Supplementation of L-glutamine enhanced mucosal immunity and improved hormonal status of combat-sport athletes. · Journal of the International Society of Sports Nutrition, 2024
“Three-week supplementation of L-glutamine after intensive training enhanced the mucosal immunity, improved hormonal status and reduced the rate of URTI of combat-sport athletes while feelings of well-being were also enhanced.”
Method: PubMed searched in humans for randomised trials with L-Glutamine in the title; these 4 of the 4 that qualified are shown with the authors’ own conclusion quoted rather than summarised. What it cannot tell you: whether L-Glutamine will work for you — each of these reports an average across trials published 2018–2025, and null findings are shown here as readily as positive ones.
How these 13 L-Glutamine products were ranked
Not one of these 13 L-glutamine products could be confirmed in the NSF, USP or Informed Sport registries, so verification separates none of them and the ranking falls to cost per day at the labelled serving. Commission does not enter it: the rate is the same whichever L-glutamine you buy. Full methodology.