L-glutamine for sickle cell disease: Knight or pawn?

Oxidative stress is an important contributor to the pathophysiology of sickle cell disease. The pathways involved are complex and interlinked. L-glutamine is an amino acid with myriad roles in the body, including the synthesis of antioxidants, such as reduced glutathione and the cofactors NAD(H) and NADP(H), as well as nitric oxide—so it has therapeutic potential as an antioxidant. However, the relative impact of L-glutamine on the redox environment in red blood cells in sickle cell disease is not fully understood, and there are few therapeutic trials in sickle cell disease. Following the FDA approval of L-glutamine for sickle cell disease, more research is still needed to understand its clinical effects and role in therapy. L-glutamine has been recently approved by the FDA for the prevention of acute complications in sickle cell disease (SCD). However, there are many gaps in our understanding of the biologic role of glutamine and its therapeutic implications in SCD. This review summarizes the pre-clinical and clinical evidence that can inform clinical decision-making and future research on glutamine therapy in SCD patients.