Not likely. Although NAD+ and NADH differ by only the respective absence or presence of an electron and NADH is a commercially available supplement, no effects of oral NADH supplements on plasma and/or cellular NAD+ levels have been reported in humans.
NADH can be converted to NAD+ via the enzyme NADH reductase, an enzyme present in mitochondria. However, NADH bioavailability is likely low when taken orally, as suggested by a rodent study, which failed to detect absorption of orally administered NADH. The investigators also found that the NADH molecule was unstable under the acidic conditions of the stomach.[1]
Although NADH supplements do seem to be safe, and have shown some potential efficacy in helping to improve energy levels and quality of life levels in people with chronic fatigue syndrome,[2][3][4] the mechanism(s) at work are not clear, and may occur independently of NAD+.