Repair of damage DNA requires large amounts of NAD+ for use by an enzyme called PARP, which is integral to DNA repair. Sirtuins which also play a key role in delaying aging also rely on NAD+ as a substrate.
On of the major intracellular signs of aging is damage of DNA by reactive oxygen species (ROS). Since DNA repair depends on NAD+, in the current study researchers sought to answer the question as to whether NAD+ levels decline in aged tissue.
The used skin samples taken from the pelvic region (no sun exposure) in subjects ranging from newborn to 77 years old. The tissues were then analyzed for NAD+ and other enzyme levels.
It was found that DNA damage was strongly correlated with age, as was the levels of the repair enzyme PARP. Furthermore, “a strong negative correlation was observed between NAD+ levels and age in both males and females.”
“This study provides quantitative evidence in support of the hypothesis that hyperactivation of PARP due to an accumulation of oxidative damage to DNA during aging may be responsible for increased NAD+ catabolism in human tissue,” conclude the authors. “The resulting NAD+ depletion may play a major role in the aging process, by limiting energy production, DNA repair and genomic signalling.”
The authors postulate that increasing the body’s stores of DNA+ could potentially protect against aging but caution “the therapeutic benefit of this approach in humans is yet to be established.” It is possible to consume NADH supplements.