Many cells can not use NAD+ straight from the blood as NAD+ could not readily go or pass through the cellular membrane layer. Muscle mass tissue, as an example, depends upon the cell's inner recycling of NAD+ via the salvage path which is controlled by Nampt. To restore your depleted NAD+ levels in such cells, the material that makes NAD must: 1- Be offered in the bloodstream. 2- When inside a cell, have the ability to bypass the Nampt traffic jam. NAM: NAM is plentiful in the blood and also conveniently carried into such cells throughout the body, yet depends on Nampt, which is the rate-limiting enzyme in the salvage path. So this isn't efficient. NA and also Tryptophan: NA and also Tryptophan act with the Afresh path, which provides a small portion of our NAD+, mostly in the liver. So If the liver is all you care about, this may be ok. NR: When taken by mouth as a supplement, most NR doesn't get through your gastrointestinal system undamaged since it is broken down to NAM. NR can bypass the Nampt traffic jam however is not normally offered in the bloodstream, and as a dietary supplement, it cannot be injected to bypass the gastrointestinal tract undamaged. After NMN supplementation, levels of NMN in the bloodstream are promptly raised and stay high longer compared to NAM, NA, or NR.