Cell biology and proposed mechanisms
Superoxide dismutase (SOD)
Superoxide dismutase is an enzyme that converts superoxide, a reactive by-product of normal breathing at the cellular level, into hydrogen peroxide and ordinary oxygen. It is the first line of the body's built-in antioxidant defence, and works alongside catalase, which clears the peroxide it makes.
Also called SOD, SOD1, SOD2, SOD3
What it does
Superoxide (O₂⁻) leaks continuously from the mitochondrial electron transport chain and is also made deliberately by immune cells. Superoxide dismutase converts two superoxide molecules into one hydrogen peroxide and one oxygen molecule. It is one of the fastest enzymes known.
Humans have three forms in different places: SOD1 (copper-zinc, in the cytoplasm), SOD2 (manganese, inside mitochondria) and SOD3 (extracellular). SOD does not finish the job — hydrogen peroxide is itself reactive, and catalase and glutathione peroxidase clear it.
Why it appears in ozone material
SOD is commonly listed among the enzymes proposed to rise downstream of Nrf2, though the best-characterised Nrf2 target genes are others — NQO1, HO-1, GCLC/GCLM and glutathione reductase. Sagai and Bocci list it first among the enzymes they propose ozone induces (Medical Gas Research, 2011). SOD activity was one of the biochemical parameters measured in the 1998 rat preconditioning study in Mediators of Inflammation.
Research so far
Induction of SOD by ozone has been shown in cell culture, and in animals given ozone by routes other than a sauna. There is a wider point worth knowing too: Antioxidants prevent health-promoting effects of physical exercise in humans, PNAS (2009), found that vitamin supplements blocked the exercise-induced rise in SOD — a reminder of how easily an intervention can work against the adaptation it is meant to encourage.
Why it matters here
SOD is the enzyme people mean when they talk about the body's own antioxidant defences. It works hand in hand with catalase, and your cells make it themselves rather than taking it in.