By providing the body with the building blocks it needs to produce glutathione, these precursors can help enhance the absorption and efficacy of glutathione supplements
However, direct chemical analysis has shown that for every two electrons transferred from NADH to oxygen, 2.5 equivalents of ATP are synthesized and 1.5 for FADH 2
Wierda WG, OBrien S, Faderl S, Ferrajoli A, Ravandi-Kashani F, Cortes J, Giles F, Andreeff M , Koller CA, Lerner S, Kantarjian HM, Keating MJ
Difference between IV drip & IM injections

The amino acids L-citrulline and L-arginine both serve as food for NOS to produce NO from (see Figure), with L-citrulline being a precursor to L-arginine.[30],[31] In fact, a 2017 study found that lower serum levels of L-arginine and L-citrulline were more common in men having ED that was vasculogenic in nature.[32] Higher levels of arginine intake have been shown to be associated with higher serum levels of nitrite and nitrate.[33] Supplementation of L-arginine in combination with L-citrulline has been shown to have a greater impact on plasma L-arginine levels than either alone,[34] likely due in part to L-arginines extensive metabolism in the gut.[35] A 2019 systemic review and meta-analysis of randomized controlled trials concludes that supplementation with L-citrulline has a significant effect of lowering both diastolic and systolic blood pressure, with a greater effect in those with a baseline blood pressure of greater than 130/85 mmHg.[36] Studies of L-citrulline supplementation in athletes have shown a positive effect on performance with ongoing supplementation

Clinical studies have shown over and over that the vitamins make the skin brighter