CR Mimetic Stack.

Sirtuins are NAD-dependent deacylases: each deacetylation consumes a molecule of NAD and releases nicotinamide. Nicotinamide riboside enters the salvage pathway through nicotinamide riboside kinase to raise NAD availability. Anything in this category that works through sirtuins depends on that cosubstrate pool being there.

Nicotinamide mononucleotide sits one step from NAD, converted by nicotinamide mononucleotide adenylyltransferase. It feeds the same cosubstrate pool that sirtuin activity draws down. The biochemistry is settled; how much a given oral dose shifts tissue NAD in people is a separate and less settled question.

Resveratrol is the compound that defined this category, reported to act on SIRT1 and on AMPK signalling. Whether the sirtuin effect is direct or an assay artefact has been argued for years, and the AMPK route now carries more weight. It belongs in any honest description of the stack, with that uncertainty stated.

Pterostilbene is the dimethylated stilbene analogue of resveratrol, and the two methoxy groups make it more lipophilic and less exposed to the rapid glucuronidation that limits resveratrol. It is commonly paired with an NAD precursor in this category. Its own human data are thinner than resveratrol's, which the pairing should not obscure.

Spermidine induces autophagy in cell and animal work by inhibiting the acetyltransferase EP300, an effect that overlaps with what nutrient restriction does through mTOR. Wheat germ is the usual dietary source. The human evidence is largely observational and mechanistic rather than interventional.

Berberine mildly inhibits mitochondrial complex I, which raises the AMP to ATP ratio and activates AMPK, the same energy sensor that responds to reduced nutrient intake. That is the mechanism it shares with this category. It is also a potent inhibitor of several drug-metabolising enzymes, so it is not a neutral addition to a stack.

EGCG has been reported to activate AMPK and to modulate the same nutrient-sensing signalling that nutrient restriction engages. It also carries a dose-dependent hepatic burden at concentrated intakes, which is why the amount and the fed state matter. Treated together with the stilbenes, it adds polyphenol load rather than a distinct mechanism.

Quercetin appears in this category through AMPK and sirtuin-adjacent signalling and through its senolytic pairing in animal work. It also inhibits several conjugation enzymes, which is how it raises exposure to co-administered polyphenols. That interaction is a formulation consideration in a multi-polyphenol stack.

Urolithin A is produced by gut bacteria from dietary ellagitannins, and only a minority of people carry the microbiota to make it, which is why it is supplied directly. It has been studied for mitophagy, the selective clearance of damaged mitochondria, an overlap with what nutrient restriction promotes. Whether it belongs in the same stack as an NAD precursor has not been measured as a combination.

Sulforaphane modifies cysteine thiols on Keap1, releasing NRF2 to enter the nucleus and switch on the antioxidant response element gene set. Reviews of calorie restriction describe NRF2 signalling as one of the pathways engaged by nutrient restriction, so the two converge on the same stress-response programme.

Broccoli sprout extract supplies glucoraphanin, which becomes sulforaphane only when myrosinase from the plant or from gut bacteria acts on it. That conversion step is why two products with the same glucoraphanin content can deliver different amounts of the active. It is the practical way sulforaphane reaches this category.

Alpha-lipoic acid is a cofactor for the mitochondrial dehydrogenase complexes and, in its reduced form, recycles other antioxidants. It has been reported to activate AMPK in cell and animal work. Its inclusion in this category rests on that mechanistic overlap rather than on human trials of the combination.

CoQ10 carries electrons between complexes I and II and complex III, so it sits directly in the machinery this category tries to influence. It is a structural component of the electron transport chain rather than a signalling modulator. The pairing is common in mitochondrial formulas and is mechanistic rather than clinically tested as a combination.

Nicotinamide is both a precursor for NAD through the salvage pathway and a product inhibitor of sirtuins, so its effect depends on concentration and on which end of the pathway is limiting. It also consumes methyl groups when it is cleared by nicotinamide N-methyltransferase. Read the direction carefully before stacking it with an NAD precursor.

Clearing nicotinamide from a raised NAD precursor intake means methylating it, which draws on S-adenosylmethionine. Betaine remethylates homocysteine and helps keep that methyl pool supplied. This is why methyl-donor support is a standing formulation consideration alongside NAD precursors.