http://www.mskcc.org/cancer-care/herb/rooibos-tea
Rooibos was shown to enhance the activity of glutathione-S transferase and UDP-glucuronosyl transferase in rat liver (11) (16), allowing cells to protect against oxidative stress, and to reduce the effects of hepatocarcinogens. A study on the oxidative stress in rats found serum superoxide dismutase and urine 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations as markers for DNA damage to be significantly reduced following administration of rooibos (17). Some studies found that the non-oxidized teas have greater antimutagenic effects compared to the oxidized forms. This is probably due to reduction in total polyphenol content with oxidization (11) (18) (19). Rooibos also modulates immune function: It induces higher IL6, IL10 and IFN-gamma levels and increases cell-mediated immunity (3); it also increased IL2 levels while suppressing IL4 (4). The anti-inflammatory effects of rooibos are thought to be due to its inhibition of COX-2 enzyme