It is a co enzyme and is made in the body from precursors, all forms of vitamin B3: nicotinic acid, nicotinamide (aka niacinamide), and nicotinamide riboside (NR).
The book 'Lifespan" by David Sinclair goes into it in some detail.
I contracted Chronic Fatigue in my 20s and really didnt have much energy/resilience. Much better these days after changing diet, fasting and using targeted supplementation. The added benefit is a better immune system. My bloods are proof of that
