Vyver MV, et al. - The proposition explored herein was that multiple sclerosis (MS) was linked with an increased release of citrulline from the brain. Findings unveiled elevated peripheral vein (PV) plasma levels of citrulline in patients with MS. However, this did not arise from an augmented release from the brain. It was deduced that an increased plasma citrulline could serve as a promising new biomarker in MS.