Abstract
Background: Recent studies have observed low plasma glutamine concentrations in chronic fatigue syndrome (CFS) subjects. Glutamine has been shown to be essential for immune function and a key substrate in brain neurochemistry. A dysfunctional immune response to infection and/or neurotransmitter dysfunction may be associated with CFS.
Objective: To compare the glutamine status of CFS subjects to matched controls and to test the effect of L-glutamine supplementation on the symptoms associated with CFS.
Design: A 26-week, randomised, double-blind, placebo-controlled trial.
Patients: Sixteen subjects diagnosed with CFS and 16 age- and sex-matched, healthy controls.
Intervention: L-glutamine or placebo (2000 mg/day for 26 weeks).
Measurements: Plasma and muscle glutamine concentrations, complete haematology counts, lymphocyte surface marker analysis, serum cortisol and testosterone concentrations, and self-reported symptomatic status.
Results: Plasma and muscle glutamine concentrations were lower in CFS subjects than controls (P < 0.001 and P = 0.027, respectively). Significant increases in plasma (P = 0.020) and muscle (P = 0.037) glutamine concentration were observed following L-glutamine, but not placebo (P > 0.05), supplementation. However, improvements in symptomatic status were not observed in the L-glutamine group. Although six subjects showed clinical improvements during the trial, there was no change in their plasma or muscle glutamine concentrations.
Conclusions: These data suggest that while low plasma glutamine concentrations may occur coincident with CFS, they may not be directly causative of fatigue or other symptoms.