I tried the longevity infusion celebrities and athletes swear by. I'm still skeptical, but I get the appeal

Infusions to boost a molecule known as NAD are a hot wellness trend among longevity-obsessed execs and high-performing athletes. Momo Takahashi for BI These days, there is one wellness hack on the lips of celebrities, athletes, and high-flyers: NAD. It's the pep-up du jour. NAD is short for…