Redox Status in Patients Suffering from Multiple Chemical Sensitivity (MCS): A Pilot Study

Background/Objectives: Multiple chemical sensitivity (MCS) is a complex environmental illness characterized by intolerance to various environmental chemicals, affecting multiple organ systems. Despite its prevalence, MCS remains poorly understood, with limited recognition by the World Health Organisation amid challenges in diagnosis due to symptom heterogeneity. This study aimed to investigate the oxidative stress status in patients diagnosed with MCS compared to healthy controls, focusing on plasma and erythrocyte markers. Methods: Blood samples from 40 MCS patients and 40 controls were analyzed for lipid peroxidation (LPO), total antioxidant activity (TAA), adenosine triphosphate (ATP), and antioxidant enzyme activities, alongside glutathione cycle components. Results: Results revealed no significant differences in plasma LPO or TAA between groups, with a reduction in 61% ATP levels in MCS subjects. However, erythrocyte analysis showed reduced levels of glutathione (GSH) and total glutathione in MCS patients. Glutathione peroxidase (GPx) activity also decreased by 15% in erythrocytes of MCS patients, suggesting increased hydrogen peroxide detoxification at the expense of oxidation of GSH to glutathione disulfide (GSSG). Because glutathione reductase activity (GRd) did not change, this GSSG could not be reduced, the GSSG/GSH ratio increased by 46%, indicating heightened intracellular oxidative stress. Catalase (CAT) activity also remained unchanged (reduced by 9%, non-significant). Conclusions: These findings highlight the role of oxidative stress in MCS pathophysiology, particularly the disruption of the glutathione cycle within erythrocytes. The study underscores the need for further research into the molecular mechanisms underlying MCS to improve diagnostic criteria and therapeutic strategies. Understanding intracellular oxidative imbalances may provide insights into the systemic dysfunction observed in MCS patients.