Twelve weeks of NMN did not loosen stiff arteries
36 healthy middle-aged adults took 250 mg of NMN a day for 12 weeks. Pulse wave velocity drifted down but not far enough to separate the group from placebo.
What the study found
Twelve weeks of NMN left arterial stiffness where it was
Thirty-six healthy middle-aged adults took 250 mg of NMN a day for twelve weeks. Pulse wave velocity, the standard measure of how stiff arteries are, drifted down in the NMN group but not far enough to separate it from placebo. Serum nicotinamide rose; NAD itself was not what went up.
The caveat · Too small to rule out a modest gain
Thirty-six people is small for a vascular endpoint, so this cannot rule out a modest real effect. The paper's own closing line says NMN showed potential in alleviating arterial stiffness, which is a firmer reading than its numbers support. The work was done in the laboratories of a Japanese supplement company, though the authors declare no competing interests.