is glutathione the master endogenous antioxidant Glutathione: Antioxidant, Reducing Oxidative Stress, and Detoxification Antioxidants and Reactive Oxygen Species:
Description
More specialised tests such as active B12 (holotranscobalamin) or methylmalonic acid may be available through specialist referral, though availability varies across the UK

Feb 2017;107(2):301-304

(2021) used cholesterol coupled to histidine and arginine grafted polyamidoamine (PamHR) to form micelles (PamHRchol), followed by a reaction with glycyrrhizic acid (GA) to produce mixed dendritic micelles (PamHRchol/GA), and the HO-1 gene was introduced into the lungs of ALI mice as a therapeutic gene

Look for endotoxin screening
