Evidence Level
L-Glutamine is an essential nutrient that plays a critical role in supporting gut epithelial and immune cell function, serving as their primary energy source. Clinical studies have highlighted its benefits in reducing infectious complications among critically ill patients. A systematic review of 14 randomized trials involving 550 surgical and critically ill participants demonstrated that glutamine supplementation significantly decreased the risk of infectious complications (RR 0.81) and shortened hospital stays by 2.6 days, without affecting mortality rates (Novak et al., 2002). Additionally, a meta-analysis of 10 studies with 2728 critically ill patients showed that glutamine supplementation notably reduced C-reactive protein levels, indicating anti-inflammatory benefits (Gholamalizadeh et al., 2022).
In the context of gut health, L-glutamine supports intestinal barrier function and mitigates permeability. A randomized controlled trial involving 69 head and neck cancer patients found that both L-arginine and L-glutamine oral suspensions effectively reduced radiation-induced oral mucositis severity, pain, and weight loss compared to maltodextrin alone (Hassanein et al., 2025). Furthermore, a study with combat-sport athletes demonstrated that L-glutamine supplementation enhanced mucosal immunity and improved hormonal status (Lu et al., 2024).
Regarding exercise recovery, evidence remains inconsistent. While some studies suggest potential benefits for muscle soreness and performance, controlled trials have not consistently demonstrated these effects. A randomized trial assessing the safety and tolerability of an allulose amino acid-based hydration beverage including L-glutamine found no significant adverse effects but did not report specific outcomes on exercise recovery (Bloomer et al., 2024).