The reduced form of nicotinamide adenine dinucleotide phosphate (NADPH), also known as reduced coenzyme II, can be increased through various sources, such as supplementing precursors, while reducing its consumption in the body. Studies have demonstrated that intracellular NADPH production primarily occurs via four pathways: the oxidized pentose phosphate pathway (oxPPP), malic enzymes (MEs), isocitrate dehydrogenases (IDHs), and the folate metabolism pathway. By regulating the expression and activity of the enzymes involved in these pathways, NADPH levels can be effectively elevated. Understanding the precise methods for increasing NADPH not only offers new insights for drug development in disease treatment but also provides crucial theoretical and experimental support for studying its functional significance.