I am all about transparency when it comes to dietary supplements: the ingredients should be easy to find, how much of each ingredient, whether it has been third-party tested, as well as what research has been done
"Stability of protein pharmaceuticals: an update." Pharmaceutical Research
In mice, short-term NAC treatment (0.11 mM for 2 months) enhanced oocyte and embryo quality, while long-term low-dose administration (0.1 mM for up to 12 months) delayed age-related fertility decline by preserving telomere length and telomerase activity (Liu et al., 2012)
These modifications result from direct ROS attack on amino acids (proline, arginine, lysine, threonine) or indirectly via reactive aldehydes from lipid peroxidation (MDA, 4-hydroxynonenal), or through reactions with reducing sugars and advanced glycation end-products (Starosta et al., 2006)