Why do RBC need to generate NADH and NADPH

Please give any references used, thanks.

NADPH and NADH generation - Iron in Hb must be maintained in the ferrous state in order to bind O2. Ferric form of Hb = Met Hb and is unable to bind O2. NADPH is a major reducing agent in the RBC and protects against oxidation. NADPH is generated for the hexose monophosphate shunt and is required by the RBC to maintain reduced glutathione. NADH is a cofactor in the metHb reductase reaction to reduce MetHb to Hb.
http://www.aic.cuhk.edu.hk/web8/red_bloo…

Hope this helps. Good luck! :P

if I had the choice