What is the deal with NAD?
Oh, goodie. Another excellent question. The tl;dr is that research is mainly around oral supplementation with NAD precursors (NMN, NR) and not on injections, though a handful of studies do look at the intramuscular route. It seems like injectables of NAD are perhaps less effective given that they still need a mechanism by which to be absorbed into cells; precursors have established pathways that make actually affecting tissue levels of NAD more feasible. In any case, the studies on oral precursors are a mixed bag with some exciting research happening in the cognition space and even in chemotherapy support with regards to fertility in hormone sensitive cancers, while other areas remain a (very interesting) question mark.
Let’s start with what we’re even talking about here/why it is important. The very simplistic explanation is that NAD is critical for the maintenance of cellular energy (ATP) production, though it also (similarly critically) has a hand in gene expression and DNA repair. References to “NAD” can mean either the electron donating version of the molecule (NADH) or the electron accepting version of the molecule (NAD+), which you’ll see me mention a few other times (though I’ll try to keep it brief). Without NAD+ and NADH in a proper ratio, our cells risk slowly losing function and our DNA loses its ability for self-repair. From an aging perspective, it is this ratio that appears to change as we age—as more and more of our DNA requires repair and TLC (which is an inevitability), the enzymes involved in that repair process “eat up” the NAD, leaving the rest of the cells wanting (for lack of a phrase that doesn’t harken to 16th century England). The aging of it all makes sense thus far for what we know, but it is also worth mentioning we really don’t know that much about why our cells age the way they do.
From an energy perspective, the electron transport chain (the last stop before the biggest surge in ATP creation happens) requires both NADH and NAD+ to keep the assembly line in good order, but both are also required for glycolysis (the first part of the Krebs Cycle).
And—surprise!—NAD also has a heavy nutrition influence. It is made of nicotinamide which is the circulating version of niacin (vitamin B3) found in our bloodstream. Niacin in its various forms is richest in animal proteins like salmon, tuna, liver, chicken, turkey and beef but can also be found in enriched grains (pasta and whole wheat bread), legumes (peanuts, lentils), and various vegetables (mushrooms, green peas, potatoes, avocado and soy products).
Why are researchers curious about NAD/NAD-precursor supplementation? It all started with the idea that NAD or supplementation with NAD precursors like NMN (nicotinamide mononucleotide) or NR (nicotinamide riboside) may have an impact on overall lifespan and longevity. This, however, has so far not been a conclusion definitively reached amongst the scientific community. Then, it became more about specific disease states related to cognition, metabolism, and cardiovascular function.
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