In our 50s and beyond, the NAD level is only about 30% to 50% of the useful level.

NAD deficiency does not necessarily result in any visible signs, because it takes a long time for the NAD deficiency to result in major health issues.

NAD intravenous therapy is quite an expensive procedure and it takes a few hours to complete.

Not seen any published data (i.e. clinical trials) that has evaluated the efficacy or safety of NAD IV therapy, only anecdotal reports.

May have benefits to some patients with very specific conditions such as neurological diseases (e.g. Parkinson's,  Alzheimer) and also addictions .

Did a trial with 10 patients having five sessions, spread over 10 days) of IV infusion with 750 milligrams of NAD in each session.

Intracellular NAD levels didn't increase.

Saw significant (temporary) increase in inflammation biomarker hs-CRP.

NAD too large to get into cells, but could affect immune cells in blood to have some effect.

Also, NAD breaks down in the blood into NAD+ metabolites that posses their own biological functions.