I've been on Tru-Niagen for a while, late 40s.
Started based on learning about David Sinclair, and this product seemed somewhat the most trustworthy in terms of the corp making it. Although lately been considering a switch to NMN if I can find a good source.
Can I tell a difference? I don't know, but I am taking it to prevent the natural decline in NAD in midlife. I did reach great fitness levels in terms of my vo2max in Q1 for my age, until RTO crushed my routine and then a bad bout of Covid reset everything back in May.
For a dollar a day, it's cheap insurance to me if it works.