How does sublingual delivery work?

Sublingual delivers more NMN directly to the bloodstream. But the remainder isn’t “wasted”. A lot is digested by bacteria in the gut to NaMN, which then follows an entirely different pathway to NAD+.

Some continue’s to the liver where it is metabolized to NAM and excreted to the bloodstream. Those are likely not as beneficial as NMN, but not worthless. So it’s really impossible to say how much more effective sublingual NMN is in the overall process. It delivers more of the intended product.