Assume it refers to NAD+ unless the product specifically states "NADH" or "reduced NAD." In metabolism and longevity contexts, "NAD" is shorthand for the oxidized form because NAD+ is the bioactive species that drives ATP production and sirtuin activation
(PubMed) Clarke JD, Riedl K, Bella D, Schwartz SJ, Stevens JF, Ho E
This compound is attracting attention for its ability to influence fat cell biology, energy metabolism, and even markers of healthy aging without relying on appetite suppression or stimulant-based mechanisms
Independent phase-variable expression has also been observed in genes involved in haemoglobin-haptoglobin acquisition (Phillips et al., 2022) which is hypothesised to provide an adaptive response to fluctuations in haem-iron availability/source influenced by the stage or site of infection (Rao et al., 1999