Eric Verdin, in a review published in Science (2015), documented NAD+ depletion across aging tissues and its downstream effects on sirtuin enzyme activity, PARP-mediated DNA repair, and mitochondrial function
However, the bioavailability of oral glutathione is relatively low, as a significant portion may be broken down in the digestive tract before it can be absorbed into the bloodstream
However, topical TXA in cosmetic formulations is permitted
"Regulation of JNK signaling by GSTp"
Increased glucocorticoids can also result from inflammation in the brain (53)
Both peptides are appropriate for adults experiencing age-related skin changes, but your primary concern can guide which formulation to emphasize in your protocol