A new study published in Nature Metabolism has brought to light a new cellular membrane transporter specific to NMN. Encoded by the Slc12a8 gene, it allows NMN to become available inside the cells for direct NAD+ production. 

Because the NAD+ molecule cannot readily cross cell membranes to enter cells,  precursor molecules to NAD+ - such as NMN - must be used to increase bioavailable levels of NAD+.

NMN is a derivative of the B-vitamin niacin and it dramatically improves health and longevity by serving as a precursor to NAD+.

By age 50, people have about half as much NAD+ in their bodies as they did at age 20. Scientists have linked low levels of NAD+ with several chronic diseases.