DavidPerlmutterMD · 2021-01-24 · David Sinclair, David Perlmutter (host)

What Causes Aging? - with Dr. David Sinclair | The Empowering Neurologist EP. 109

33 research-tied claims examined: 1 contradicted 1 overstated 2 context 28 supported 1 unverified

Needs context

0:29:05 David Sinclairneeds contextvery low

Nutrient restriction in yeast increases intracellular NAD levels, activating sirtuins and extending yeast replicative lifespan by approximately 30%.

"And so, as levels in the yeast cells rose in response to being hungry, the sirtuins in the cell came on more active, preserved the epigenome, improved DNA repair, and the cells lived longer by about 30%." (said at 0:29:05)

Early landmark studies in yeast (Saccharomyces cerevisiae) demonstrated that caloric restriction extends replicative lifespan (typically by ~30–40%) in a manner requiring the NAD+-dependent deacetylase Sir2 and intact NAD biosynthesis pathways (e.g., Lin et al., 2000). However, the specific mechanistic assertion that calorie restriction increases intracellular NAD levels is disputed: subsequent studies showed that calorie restriction does not necessarily increase NAD+ levels, but rather activates Sir2 by lowering levels of its endogenous inhibitor nicotinamide via PNC1 induction, or operates via mechanisms independent of NAD fluctuation (Anderson et al., 2003). Because the evidence is based entirely on yeast laboratory models, the GRADE certainty is very low.

supports: Requirement of NAD and SIR2 for life-span extension by calorie restriction in Saccharomyce… (Science (New York, N.Y.) 2000) · cited 1781x in the literature
"Here, we mimicked calorie restriction in yeast by physiological or genetic means and showed a substantial extension in life-span. This extension was not observed in strains mutant for SIR2 (which encodes the silencing protein Sir2p) or NPT1 (a gene in a pathway in the synthesis of NAD, the oxidized form of nicotinamide adenine dinucleotide). These findings suggest that the increased longevity induced by calorie restriction requires the activation of Sir2p by NAD." (abstract, results, passage verified)
pubmed full study (doi)
context: Nicotinamide and PNC1 govern lifespan extension by calorie restriction in Saccharomyces ce… (Nature 2003) · cited 743x in the literature
"In Saccharomyces cerevisiae, lifespan extension by calorie restriction requires the NAD+-dependent histone deacetylase, Sir2 (ref. 1)... We provide evidence that nicotinamide depletion is sufficient to activate Sir2 and that this is the mechanism by which PNC1 regulates longevity." (abstract, results)
pubmed full study (doi)
contradicts: Yeast life-span extension by calorie restriction is independent of NAD fluctuation. (Science (New York, N.Y.) 2003) · cited 161x in the literature
"We report that CR reduces nuclear NAD+ levels in vivo. Moreover, the activity of Sir2 and its human homologue SIRT1 are not affected by physiological alterations in the NAD+:NADH ratio. These data implicate alternate mechanisms of Sir2 regulation by CR." (abstract, results, passage verified)
pubmed full study (doi)

0:31:14 David Perlmutter (host)needs contextmoderate

NAD levels decline with age and are reduced in individuals with chronic degenerative conditions.

"NAD levels, which decline with age and are seen to be declining in people who have chronic degenerative conditions" (said at 0:31:14)

The statement that NAD+ levels decline with age and are reduced in chronic degenerative diseases reflects a widely accepted paradigm heavily supported by preclinical animal research and mechanistic models. Systematic reviews note that NAD+ decline is documented across aging and degenerative disease models driven by increased consumption (e.g., via CD38 and PARP activation) and altered synthesis. However, human clinical and tissue evidence is more nuanced: while reductions have been observed in specific human tissues and age-related pathologies, evidence of generalized systemic NAD+ decline in humans remains sparse and tissue-dependent, with some recent human analyses showing variable or stable blood NAD+ levels across age groups.

supports: Role of Nicotinamide Adenine Dinucleotide and Related Precursors as Therapeutic Targets fo… (Antioxidants & redox signaling 2019) · cited 274x in the literature
"In this review, we describe and discuss recent insights regarding the efficacy and benefits of the NAD + precursors, nicotinamide (NAM), nicotinic acid (NA), nicotinamide riboside (NR), and nicotinamide mononucleotide (NMN), in attenuating NAD + decline in degenerative disease states and physiological aging." (abstract, recent advances, passage verified)
pubmed full study (doi)
supports: NAD+ therapy in age-related degenerative disorders: A benefit/risk analysis. (Experimental gerontology 2020) · cited 91x in the literature
"NAD+ levels have been reported to decline during ageing and age-related diseases. Recent studies have shown that raising intracellular NAD+ levels represents a promising therapeutic strategy for age-associated degenerative diseases in general and to extend lifespan in small animal models." (abstract, background, passage verified)
pubmed full study (doi)
context: NAD + precursor supplementation in human ageing: clinical evidence and challenges. (Nature metabolism 2025) · cited 25x in the literature
"However, evidence for an age-related decline in NAD + levels in humans has been consistently observed only in a limited number of studies. Similarly, although preclinical studies support the idea that supplementation with NAD + precursors is a promising therapeutic strategy to promote healthy ageing, human clinical trials have shown limited efficacy." (abstract, background, passage verified)
pubmed full study (doi)

Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.