Most of the NAD supplement research has been done in rodents
Of 113 NAD studies from 2010 to October 2025, 80 were in rodents. In the 33 human ones the compounds raised blood metabolites while effects on function were inconsistent.
What the study found
The NAD supplement literature is 80 rodent studies to 33 human
Of 113 studies from 2010 to October 2025 testing ways to boost nicotinamide adenine dinucleotide (NAD), a review found 80 in rodents. In the 33 human ones, NAD-related metabolites in blood reliably rose; effects on function, metabolism and blood vessels were inconsistent or absent.
The caveat · Human trials too varied to pool
The search closed in October 2025, so anything published since is missing. The human trials measured such different things that they could not be pooled, which makes the null conclusion a reading of the literature rather than a calculated number. The review also found no outcomes trial at all of intravenous NAD, which is sold commercially.