There is evidence that melatonin can be synthesized in other sites of the body (skin, gastrointestinal tract, retina, bone marrow, placenta and others) acting in an autocrine or paracrine manner (10)
These studies are exploratory and intended to clarify mechanisms, with no human or veterinary purpose
Some evidence suggests that increasing NAD may lower the risk for obesity and metabolic syndrome and the conditions they can cause, including heart disease, type 2 diabetes, and stroke, but the science is mixed with some research showing no improvements related to insulin resistance
The key effects are well-established: accelerated cell turnover (the outer layers of the stratum corneum, the skin's surface barrier, shed more quickly), direct stimulation of procollagen genes, and suppression of matrix metalloproteinases - the enzymes responsible for breaking down existing collagen