The blood-pressure claim traces to a trial that found no effect
Twenty-four healthy middle-aged and older adults took 1,000 mg a day for six weeks. On blood pressure and arterial stiffness the authors reported no effect.
What the study found
The vascular result people cite from this trial was a suggestion
Twenty-four healthy middle-aged and older adults took 1,000 mg of nicotinamide riboside a day for six weeks. It was tolerated and stimulated nicotinamide adenine dinucleotide metabolism. The authors found no effect on blood pressure or arterial stiffness and recommended testing for one.
The caveat · A tolerability study, not a test
Twenty-four people in a crossover design, six weeks per arm, all of them healthy, so this is an early tolerability and target-engagement study rather than a test of anything. NAD was measured in blood, which shows the pill is absorbed and metabolised, not that it reached the tissues where ageing is supposed to slow. The trial was investigator-initiated at a university with no declared competing interests, which sets it apart from most of this literature.
What we don't know
Twenty-four people in a crossover design, six weeks per arm, all of them healthy, so this is an early tolerability and target-engagement study rather than a test of anything. NAD was measured in blood, which shows the pill is absorbed and metabolised, not that it reached the tissues where ageing is supposed to slow. The trial was investigator-initiated at a university with no declared competing interests, which sets it apart from most of this literature.