Oxidative modifications to cellular substrates can be detrimental but can also play a key role in normal regulatory processes such as protein function. Cells rely on specialized systems such as 8-oxoguanine DNA glycosylase (OGG1) and phospholipid hydroperoxide glutathione peroxidase (PHGPx) to repair DNA and Lipids.

Other systems such as thioredoxin (TRX), methionine sulfoxide reductase (MSRA and MSRB) and glutathione S-transferase (GST) are in place to deal with disulfide bond formation, methionine oxidation and xenobiotic regulation. These specific "repair mechanisms" can be measured to lend insight into oxidative stress levels and mechanisms of impact.