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FoundMyFitness · 2019-11-06 · Rhonda Patrick (host), David Sinclair

Dr. David Sinclair on Informational Theory of Aging, Nicotinamide Mononucleotide, Resveratrol & More

51 claims checked against research: 6 contradicted 1 overstated 3 needing context 37 supported 4 unverified

37

Supported by research

0:01:03David Sinclairsupportedhigh

Longevity genes were first discovered in model organisms such as nematode worms and yeast.

"And so these longevity genes were first found in organisms like a nematode worm, tiny little one, and yeast cells that we use for baking and bread." (said at 0:01:03)

The discovery of single-gene mutations and regulatory pathways that influence lifespan (longevity genes) originated in simple eukaryotic model organisms. The initial identification and characterization of key longevity genes—such as age-1 and daf-2 in the nematode worm Caenorhabditis elegans and SIR2 in the budding yeast Saccharomyces cerevisiae—demonstrated that single-gene manipulations could significantly extend lifespan across species.

0:02:22Rhonda Patrick (host)supportedvery low

Nematode worms with decreased insulin/IGF-1 signaling live approximately 100% longer than wild-type worms.

"I remember the first time I was working with these worms that had a decreased insulin/IGF-1 signaling pathway, how they lived like 100% longer, and how they were like youthful when they were supposed to be dead." (said at 0:02:22)

Preclinical genetic studies in Caenorhabditis elegans demonstrate that reducing signaling through the insulin/IGF-1 pathway, such as via loss-of-function mutations in the insulin/IGF-1 receptor homolog daf-2, extends adult lifespan by more than twofold (over 100%) compared to wild-type worms, while maintaining active mobility. Because this evidence is derived exclusively from invertebrate animal models, the certainty of evidence for broader application is very low.

0:05:39David Sinclairsupportedvery low

Inserting an extra copy of the SIR2 gene into yeast extends their lifespan by 30%.

"Matt Kaeberlein, who's now out in Seattle, who's a leader in the field as well, he came in and his first project in the lab was to put an extra copy of one of the Sir genes, number two, SIR2, into yeast, and those yeast lived 30% longer." (said at 0:05:39)

In a landmark 1999 study by Kaeberlein, McVey, and Guarente, researchers introduced an extra integrated copy of the SIR2 gene into wild-type Saccharomyces cerevisiae yeast, which increased their replicative lifespan by approximately 30% (from an average of roughly 18 generations to 24 generations). Because this finding is based entirely on single-cell model organism (yeast) laboratory experiments, certainty is graded as very low.

0:07:40David Sinclairsupportedvery low

Dropping sugar levels fivefold in petri dishes extends yeast lifespan.

"With yeast, if you're wondering how do you calorie-restrict a yeast, we just dropped the level of sugar in the petri dish. I think it was fivefold, and that was enough to make them live longer, and but they still grow quite happily." (said at 0:07:40)

Laboratory models of calorie restriction in budding yeast (Saccharomyces cerevisiae) routinely lower the glucose concentration in the agar growth media (typically from the standard 2.0% down to 0.5% or 0.4%, representing a four- to fivefold reduction). This dietary restriction reliably extends both replicative and chronological lifespan while allowing the yeast cells to continue proliferating. Because the evidence is derived exclusively from in vitro unicellular organism models, the GRADE certainty is very low.

0:09:12David Sinclairsupportedhigh

Humans have seven distinct sirtuin genes.

"the levels of one of the sirtuin genes, the number one—we have seven of these genes, so we looked at number one because we only had an antibody in those days to number one" (said at 0:09:12)

Humans and other mammals possess seven distinct sirtuin genes, designated SIRT1 through SIRT7, which encode NAD+-dependent deacetylases and deacylases located across different cellular compartments (nucleus, cytoplasm, and mitochondria).

0:09:12David Sinclairsupportedvery low

In a 2005 Science study, calorie restriction increased SIRT1 protein levels five- to tenfold in rat liver.

"so we showed in 2005 in a Science paper that when you take a calorie-restricted rat and look at its organs—we looked at the liver and muscle—the levels of one of the sirtuin genes, the number one... went up dramatically. I think it was about five- to tenfold in levels in the calorie-restricted livers." (said at 0:09:12)

The speaker correctly describes the findings of a study from their laboratory published in Science (Cohen et al., published in July 2004 rather than 2005), which demonstrated that calorie restriction induces SIRT1 protein expression across multiple tissues in rats, including liver, brain, kidney, and fat, compared to ad libitum-fed controls. Evidence is limited to animal and in vitro models, warranting very low GRADE certainty for broader translation.

0:09:35David Sinclairsupportedvery low

Serum from calorie-restricted animals stimulates sirtuin production in cultured cells, which is reversed by adding normal levels of insulin and IGF-1.

"We grew cells in serum from animals that had been calorie restricted and we found that that was also enough to stimulate this boost of sirtuin production. But getting back to what you did in Andy Dillin's lab, we found out that the reason it went up in the dish was because of having low insulin and IGF-1 levels, because when we put back in normal insulin levels and IGF-1, the sirtuins went back down." (said at 0:09:35)

The speaker accurately recounts experimental findings published in Science (Cohen et al., 2004). In that study, culturing human cells in serum from calorie-restricted rats induced expression of the mammalian sirtuin SIRT1, and the addition of insulin and insulin-like growth factor 1 (IGF-1) attenuated this induction. Because the supporting evidence consists of in vitro cell culture and rodent models, the overall certainty regarding physiological and clinical implications in humans is very low.

0:11:20David Sinclairsupportedhigh

NAD+ levels rise during fasting and exercise, and fluctuate with circadian rhythms.

"the levels of NAD go up and down depending on not just what you eat, but whether you're exercising and even what time of day it is. So during the day, your NAD levels will rise, and then you eat a big meal and they'll go down again." (said at 0:11:20)

The speaker claims that NAD+ levels fluctuate with circadian rhythms, rise during exercise/fasting, and drop after eating a large meal. In human and rodent studies, intracellular NAD+ levels and its key rate-limiting biosynthetic enzyme, nicotinamide phosphoribosyltransferase (NAMPT), display robust circadian oscillations regulated by CLOCK:BMAL1 and SIRT1 (PMID: 19299583, PMID: 19286518). Furthermore, human clinical trials and systematic reviews demonstrate that acute exercise and exercise training upregulate NAMPT and elevate intracellular NAD+ levels (PMID: 39500416, PMID: 37954044, PMID: 36599416). High energy demand or fasting increases cellular NAD+ levels, whereas high nutrient/caloric intake leads to a drop in the NAD+/NADH ratio as NAD+ is consumed and reduced to NADH during nutrient oxidation.

0:14:51Rhonda Patrick (host)supportedmoderate

NAD+ levels decline with age.

"So NAD levels decrease with age, and you think this plays a causal role in the aging process, right? Right." (said at 0:14:51)

Preclinical animal models and human observational studies consistently show that cellular and tissue levels of nicotinamide adenine dinucleotide (NAD+) decrease with advancing age due to decreased biosynthesis and increased enzymatic consumption. While human tissue-specific dynamics continue to be investigated, the age-associated decline in systemic and cellular NAD+ is a widely recognized hallmark in the biology of aging.

0:19:20David Sinclairsupportedvery low

SIRT1/Sir2 relocates to broken chromosome ends within seconds, bringing in HDAC1 to remodel chromatin for DNA repair.

"Mills, myself, and Guarente published that Sir2 goes to a broken DNA end and then helps recruit other proteins... the first thing that happens is gamma-H2AX gets lit up on the break, and then within seconds SIRT1 brings in HDAC1, helps remodel the DNA and the chromatin so that's ready for the repair proteins to come in." (said at 0:19:20)

Published mechanistic research in yeast, mammalian cell culture, and rodent models supports the sequence of events described. In 1999, Mills, Sinclair, and Guarente demonstrated that the yeast Sir silencing complex relocates from telomeres to DNA double-strand breaks (DSBs) to promote repair. Subsequent mammalian studies have shown that following DSB induction (marked by phosphorylated histone H2AX, or gamma-H2AX), SIRT1 is rapidly recruited to break sites, where it physically interacts with and deacetylates HDAC1 to stimulate its deacetylase activity and facilitate chromatin remodeling required for DSB repair (such as via non-homologous end joining). Because this evidence is derived entirely from pre-clinical cell culture and animal models, the GRADE certainty is very low.

0:22:40David Sinclairsupportedmoderate

The Horvath DNA methylation clock predicts chronological age as well as all-cause mortality and remaining lifespan.

"his research is really interesting in that it is showing that it doesn't just predict your chronological age; it's predicting also how long you have to live, which is a really interesting thing. That if you've abused your body and had a lot of smoking and you're sedentary, Steve can take your blood and he can say, 'Hey, you're 10 years older than you should be.'" (said at 0:22:40)

Steve Horvath's DNA methylation clock was originally developed to estimate chronological age from tissue and blood DNA methylation patterns. Subsequent large prospective cohort studies and meta-analyses confirmed that the discrepancy between DNA methylation age and chronological age (epigenetic age acceleration) independently predicts all-cause mortality, time-to-death, and cancer mortality, even after adjusting for chronological age, demographic variables, and major lifestyle and cardiovascular risk factors.

0:25:44David Sinclairsupportedvery low

Transgenic expression of four Yamanaka factors (OSKM) caused rapid death in mice, but cyclic expression extended lifespan in a progeria mouse model by over 40%.

"he made a mouse where he could turn on these four Yamanaka genes—and for short, they stand for OSKM—and that mouse, when he switched them on, died within a couple of days... What he did was he turned the genes on for a couple of days and then stopped, let the mice recover for a few days, and then turned them back on... The premature aging mouse model that he had lived, I think was 40-plus percent longer." (said at 0:25:44)

A landmark 2016 study led by Juan Carlos Izpisua Belmonte's laboratory (Ocampo et al., Cell) demonstrated that continuous in vivo transgenic expression of the four Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc; OSKM) resulted in rapid lethality due to severe tissue dysplasia and organ failure. However, implementing a short-term cyclic induction protocol (2 days on, 5 days off) avoided teratoma formation and premature death, extending the median lifespan of a transgenic mouse model of Hutchinson-Gilford progeria syndrome (LmnaG609G/G609G) by approximately 30% to 50% (over 40%) compared to untreated controls.

0:26:44David Sinclairsupportedvery low

Cyclic expression of Yamanaka factors improves wound healing and kidney healing in mice.

"he's shown since then that you can use these factors to improve wound healing and kidney healing." (said at 0:26:44)

Animal research from Juan Carlos Izpisua Belmonte's group has demonstrated that cyclic, in vivo expression of the Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc; OSKM) promotes tissue repair and rejuvenating effects in mice, specifically in skin and kidney tissues. In a 2022 study evaluating long-term partial reprogramming in naturally aging mice, cyclic OSKM induction enhanced wound closure in skin injury models and mitigated age-associated histological and molecular biomarkers of injury in the kidney. Because these findings are derived entirely from preclinical rodent models, their applicability to human healing remains unproven.

0:24:44David Sinclairsupportedhigh

Shinya Yamanaka discovered four transcription factors that reprogram adult somatic cells into pluripotent stem cells, research for which he was awarded the Nobel Prize in 2012.

"Well, the first person to use these factors was Shinya Yamanaka, a Japanese scientist who looked through a lot of different genes and found a set of four factors that if you put them into an adult cell, say a skin cell, they would go back to being very primitive. So primitive, what we call a pluripotent stem cell... that led to the Nobel Prize being awarded to him in 2012." (said at 0:24:44)

Shinya Yamanaka and colleagues screened 24 candidate genes and identified a cocktail of four transcription factors—Oct3/4, Sox2, Klf4, and c-Myc (the 'Yamanaka factors')—capable of reprogramming adult mouse fibroblasts and adult human dermal fibroblasts into induced pluripotent stem cells (iPSCs). For the discovery that mature cells can be reprogrammed to become pluripotent, Shinya Yamanaka was awarded the Nobel Prize in Physiology or Medicine in 2012 alongside Sir John B. Gurdon.

0:22:09David Sinclairsupportedmoderate

The Horvath DNA methylation clock shows accelerated epigenetic aging in individuals who smoke or are obese.

"And actually, the Horvath clock has now been done on people who are smokers or obese, and it's quite clear." (said at 0:22:09)

Multiple large-scale cohort studies evaluating DNA methylation biomarkers have demonstrated that obesity and cigarette smoking are significantly associated with accelerated epigenetic aging, including when evaluated using the Horvath epigenetic clock. Horvath and colleagues demonstrated that obesity significantly accelerates epigenetic aging in human tissues (such as liver tissue, increasing by ~3.3 years per 10 BMI units). In multi-cohort studies examining the Horvath, Hannum, and PhenoAge/Levine clocks across thousands of participants, both smoking and obesity (or elevated BMI) consistently correlate with epigenetic age acceleration, with smoking often exerting a particularly strong effect on biological age measures.

0:17:25David Sinclairsupportedmoderate

Activation of PARP enzymes during DNA repair acts as a major consumer and drain on cellular NAD+ levels.

"the immune system is a big drain on NAD, and actually so is DNA repair with the activation of PARPs." (said at 0:17:25)

Published literature firmly establishes that poly(ADP-ribose) polymerase (PARP) enzymes, particularly PARP-1, utilize nicotinamide adenine dinucleotide (NAD+) as a substrate to synthesize poly(ADP-ribose) polymers during the cellular DNA damage response. In the presence of genotoxic stress or accumulated DNA damage, PARP activation significantly consumes and depletes intracellular NAD+ pools.

0:27:01David Sinclairsupportedlow

The Myc gene is an oncogene, and omitting it from the Yamanaka reprogramming factor cocktail reduces toxicity in reprogramming.

"We have to leave one of those off because it's toxic. It's the Myc gene. Myc is an oncogene. But the other three work great" (said at 0:27:01)

The original four Yamanaka factors used to generate induced pluripotent stem cells (iPSCs) are Oct3/4 (Oct4), Sox2, Klf4, and c-Myc. c-Myc is a well-established proto-oncogene whose reactivation poses severe risks of tumorigenicity and aberrant proliferation in reprogrammed cells and chimeric animal models. Landmark reprogramming studies demonstrated that iPSCs can be successfully generated using only the remaining three factors (Oct4, Sox2, and Klf4; often abbreviated OSK), significantly reducing background transformed cells and preventing tumor formation in derived mice.

0:31:38David Sinclairsupportedhigh

Yamanaka factors reset the epigenome of differentiated cells.

"You actually reset the epigenome, and that's how it works." (said at 0:31:38)

Expression of the Yamanaka transcription factors (OCT4, SOX2, KLF4, and c-MYC) in differentiated somatic cells converts them into induced pluripotent stem cells (iPSCs) by clearing cell-type-specific epigenetic marks, altering chromatin accessibility, and resetting the epigenetic state to resemble that of embryonic stem cells.

0:34:32David Sinclairsupportedvery low

Shelley Berger's research at UPenn showed that the difference between short-lived and long-lived ants is determined by different epigenomes.

"And we have Shelley Berger at UPenn, who's been studying, among other things, what makes the difference between a short-lived ant and a long-lived ant, and that seems to be just different epigenomes." (said at 0:34:32)

Research led by Shelley Berger at the University of Pennsylvania established ants (specifically Camponotus floridanus and Harpegnathos saltator) as model systems to study how epigenetic differences drive distinct caste phenotypes, behaviors, and lifespans despite shared genomes. In these ant species, genetically identical individuals can develop into short-lived nonreproductive worker castes or dramatically longer-lived reproductive queens/gamergates, governed by caste-specific epigenomic features including differential DNA methylation, histone modifications, and transcriptional regulators.

0:35:35David Sinclairsupportedhigh

John Gurdon demonstrated that cellular aging and genomic programming can be reset by transferring an adult tadpole cell nucleus into an enucleated frog egg to generate a new tadpole.

"What he did was he took an adult cell nucleus from a tadpole, put it into a frog's egg, and made a new tadpole. What that actually tells you is that your genome can be reset to going way back, and aging is not a one-way street." (said at 0:35:35)

John Gurdon's landmark 1962 experiments demonstrated somatic cell nuclear transfer by introducing the nucleus of a differentiated intestinal epithelial cell from a feeding Xenopus laevis tadpole into an enucleated frog egg, resulting in the development of normal, swimming tadpoles. This discovery proved that cell differentiation does not involve irreversible loss of genetic material and that genomic programming can be reset, work for which Gurdon was awarded the Nobel Prize in Physiology or Medicine in 2012. While tadpoles represent the larval (rather than adult) stage of frog development, the donor cells were fully differentiated somatic epithelial cells.

0:36:22David Sinclairsupportedvery low

Long-lived animals such as whales and naked mole-rats have a very stable epigenome.

"Animals like whales and naked mole-rats have a very stable epigenome." (said at 0:36:22)

Comparative biology research supports the concept that exceptionally long-lived species exhibit enhanced epigenetic stability. For example, research in naked mole-rat (NMR) cells demonstrated that they possess a more stable epigenome characterized by higher repressive histone methylation marks (H3K27me3), lower activating marks, more closed promoter regions, and strong resistance to cellular de-differentiation and reprogramming compared to shorter-lived rodents like mice. Evidence for this claim is currently derived from in vitro and comparative animal models.

0:37:58David Sinclairsupportedvery low

A cellular transporter directly takes up nicotinamide mononucleotide (NMN) into cells.

"If you give a cell NMN, it will be taken up by a transporter, which was just discovered by my buddy Shin Imai. We used to work at MIT, now he's at WashU. A few weeks ago he wrote about it, I wrote about it, that there's a transporter that sucks up NMN" (said at 0:37:58)

The claim accurately describes the discovery by Shin-ichiro Imai's laboratory (Grozio et al., 2019, Nature Metabolism) identifying Slc12a8 as a specific, sodium-dependent cellular transporter that directly mediates the uptake of nicotinamide mononucleotide (NMN) into cells in vitro and in murine models. Because this evidence is derived from preclinical cellular and animal models, the GRADE certainty is rated very low.

  • supports: Slc12a8 is a nicotinamide mononucleotide transporter. (Nature metabolism 2019) · cited 283x in the literature
    "Here we show that the Slc12a8 gene encodes a specific NMN transporter. We find that Slc12a8 is highly expressed and regulated by NAD + in the murine small intestine. Slc12a8 knockdown abrogates the uptake of NMN in vitro and in vivo . We further show that Slc12a8 specifically transports NMN, but not nicotinamide riboside, and that NMN transport depends on the presence of sodium ion." (abstract, results, passage verified)
    pubmedfull study (doi)
0:38:51David Sinclairsupportedhigh

Nicotinamide riboside (NR) is a molecule that lacks a phosphate group compared to NMN and must first be phosphorylated into NMN before being synthesized into NAD.

"It stands for nicotinamide riboside, and all it is, it's just a smaller version of NMN without a phosphate on there, so there's no phosphorus on it. And so if you take NR, your body has to first put on a phosphorus and then it has to basically link two of them together to make the NAD." (said at 0:38:51)

Nicotinamide riboside (NR) is a ribonucleoside consisting of nicotinamide linked to a ribose ring, lacking the 5'-phosphate group present in nicotinamide mononucleotide (NMN). In cellular NAD+ biosynthesis, NR is phosphorylated to NMN by nicotinamide riboside kinases (NRK1/NRK2) before being converted into the dinucleotide NAD+ (via adenylation by nicotinamide mononucleotide adenylyltransferases, NMNAT).

0:39:14David Sinclairsupportedhigh

Both nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) have been demonstrated to raise NAD levels in animals and humans.

"But NR and NMN have both been shown to raise the NAD levels in animals and in humans as well." (said at 0:39:14)

Multiple randomized controlled trials and preclinical animal studies demonstrate that oral supplementation with both nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) significantly increases blood NAD+ levels in humans as well as NAD+ concentrations in animal tissues.

0:42:50Rhonda Patrick (host)supportedvery low

In a study by Rafael de Cabo's group, resveratrol supplementation completely reversed the 40% increase in aortic stiffness induced by a high-sucrose and high-fat diet in rhesus monkeys.

"And basically, feeding these monkeys, they were feeding them this terrible high-sucrose diet, high sucrose and high fat, and it caused them to have like 40% increased aortic stiffness, but the resveratrol completely ameliorated it." (said at 0:42:50)

A 2014 study led by Rafael de Cabo and colleagues evaluated the effects of a 2-year high-fat, high-sucrose (HFS) diet with or without resveratrol supplementation in rhesus monkeys. The HFS diet led to central arterial wall stiffening (measured via aortic pulse wave velocity) and inflammation, whereas concurrent dietary supplementation with resveratrol prevented this stiffening and associated arterial wall inflammation. Because this evidence comes from an animal model, the certainty for human health outcomes is graded as very low.

0:45:17David Sinclairsupportedlow

Trans-resveratrol activates the SIRT1 enzyme, whereas the cis-resveratrol isomer does not.

"I go for the trans, because when we gave the cis form to the sirtuin enzyme, it didn't activate it, but the trans worked brilliantly." (said at 0:45:17)

In vitro enzyme activation studies of sirtuins demonstrated that trans-resveratrol stimulates SIRT1 deacetylase activity, whereas the cis-resveratrol isomer lacks this activating capacity. The original screen identifying small-molecule sirtuin activators showed that trans-resveratrol lowers the Michaelis constant (Km) of SIRT1 for both NAD+ and the acetylated substrate, whereas cis-stilbene/resveratrol analogues failed to activate the enzyme in the assay.

0:45:25David Sinclairsupportedvery low

In mice fed a high-fat diet, resveratrol prevented fatty arterial plaque accumulation and extended lifespan despite the mice remaining obese.

"He did the study with us on the mouse resveratrol study that showed that on a high-fat diet, those mice were extremely healthy and longer-lived, and their organs, when they opened up the mice, they were pristine. So the mice were still obese, because we didn't give them a lot of resveratrol, it was pretty low dose, but their organs were so beautiful. Their arteries, when you stained them for oil or fat, it was night and day: the ones on resveratrol versus the ones without resveratrol were stained with fatty lumps, resveratrol clean." (said at 0:45:25)

The speaker's description matches the findings of the 2006 study by Baur et al. (co-authored with Rafael de Cabo and David Sinclair), in which middle-aged mice maintained on a high-calorie diet and treated with resveratrol exhibited significantly increased survival and improved physiological and tissue markers compared to untreated high-calorie controls, despite remaining obese. However, because this evidence comes entirely from animal models, the overall certainty for human health translation is very low.

  • supports: Resveratrol improves health and survival of mice on a high-calorie diet. (Nature 2006) · cited 4259x in the literature
    "Here we show that resveratrol shifts the physiology of middle-aged mice on a high-calorie diet towards that of mice on a standard diet and significantly increases their survival. Resveratrol produces changes associated with longer lifespan, including increased insulin sensitivity, reduced insulin-like growth factor-1 (IGF-I) levels, increased AMP-activated protein kinase (AMPK) and peroxisome proliferator-gamma coactivator 1alpha (PGC-1alpha) activity, increased mitochondrial number, and improved motor function." (abstract, results, passage verified)
    pubmedfull study (doi)
0:50:57David Sinclairsupportedvery low

Boosting NAD levels in the brain improves memory and slows Alzheimer's disease progression in mouse models.

"So at least in mice, a couple of labs have published now in top journals like Cell that raising the NAD levels in the brain also improves memory and slows down the advancement of Alzheimer's in mice." (said at 0:50:57)

Preclinical studies in mouse models of Alzheimer's disease consistently demonstrate that elevating brain NAD+ levels—using precursors such as nicotinamide riboside (NR), nicotinamide mononucleotide (NMN), or nicotinamide—improves learning and memory and attenuates disease pathology, including amyloid-beta accumulation, neuroinflammation, and synaptic dysfunction. A 2021 systematic review of rodent studies confirmed these pro-cognitive and neuroprotective effects. However, because this evidence is derived entirely from animal models, its certainty for human Alzheimer's disease treatment remains very low.

0:59:15Rhonda Patrick (host)supportedvery low

A 2016 study by Shin-ichiro Imai showed that long-term administration of NMN over 12 months mitigated physiological decline and delayed tissue aging across multiple organs in wild-type mice.

"I was super excited, I think it was a 2016 Cell paper you mentioned, the group that published the NMN basically that was given to normal mice— [...] Shin-ichiro Imai's study, yeah. [...] And basically, I think it was about 200 milligrams per day. Like that dose, as I remember looking at the dose and going, this is significantly lower than the nicotinamide riboside dose. And it seemed to delay tissue aging in multiple organs" (said at 0:59:15)

A 2016 study published in Cell Metabolism by Shin-ichiro Imai and colleagues (Mills et al.) evaluated 12 months of oral nicotinamide mononucleotide (NMN) administration in normal-aging, wild-type C57BL/6N mice. The study demonstrated that long-term NMN supplementation mitigated age-associated physiological decline across multiple systems, including suppressing age-related weight gain, enhancing energy metabolism and physical activity, improving insulin sensitivity and lipid profiles, enhancing skeletal muscle mitochondrial function, and improving eye function, without apparent toxicity. Because the evidence is derived solely from animal models, the GRADE certainty is very low for human translation.

  • supports: Long-Term Administration of Nicotinamide Mononucleotide Mitigates Age-Associated Physiolog… (Cell metabolism 2016) · cited 928x in the literature
    "In this study, we conducted a 12-month-long NMN administration to regular chow-fed wild-type C57BL/6N mice during their normal aging. Orally administered NMN was quickly utilized to synthesize NAD + in tissues. Remarkably, NMN effectively mitigates age-associated physiological decline in mice. Without any obvious toxicity or deleterious effects, NMN suppressed age-associated body weight gain, enhanced energy metabolism, promoted physical activity, improved insulin sensitivity and plasma lipid profile, and ameliorated eye function and other pathophysiologies." (abstract, results, passage verified)
    pubmedfull study (doi)
0:47:39David Sinclairsupportedmoderate

A clinical study demonstrated that resveratrol supplementation interfered with and blunted physiological adaptations to endurance exercise in humans.

"There was one study where it interfered with endurance exercise, don't understand that." (said at 0:47:39)

A randomized controlled trial (Gliemann et al., 2013) evaluated the effect of daily 250 mg trans-resveratrol versus placebo during 8 weeks of exercise training in 27 inactive older men. The placebo group achieved a 45% greater increase in maximal oxygen uptake (VO2max) compared to the resveratrol group. Resveratrol also blunted training-induced reductions in mean arterial pressure, improvements in blood lipid profiles, and skeletal muscle angiogenic responses.

0:52:11David Sinclairsupportedvery low

Administration of NMN and NR promotes blood flow and stimulates vascular capillary regrowth in skeletal muscle in mice.

"we've shown that NMN and others have shown for NR that it also helps with blood flow and actually mimics exercise and regrows the vascular system. And we've done that for muscle." (said at 0:52:11)

Preclinical research demonstrates that treatment with the NAD+ precursor nicotinamide mononucleotide (NMN) restores endothelial NAD+ levels, increases SIRT1 activity, stimulates capillary angiogenesis, and improves blood flow and endurance in skeletal muscle of aged mice. Because the supporting evidence comes strictly from animal (mouse) models, certainty is graded as very low regarding whether these effects translate directly to humans.

0:52:53Rhonda Patrick (host)supportedvery low

A study by Rabinowitz's group showed that orally administered nicotinamide riboside at 200 mg/kg synthesized NAD in the liver but failed to form NAD in skeletal muscle.

"This was this NAD flux paper that was done by Rabinowitz... That study he recently published just a few months ago looking at nicotinamide riboside and how, orally, at a dose half of what typically is used... showed nicotinamide riboside given orally didn't form NAD in muscle, but it did in the liver" (said at 0:52:53)

A landmark quantitative isotope-tracer flux study by Joshua Rabinowitz's group (Liu et al., Cell Metabolism 2018, PMID: 29685734) demonstrated tissue-specific NAD synthesis and precursor utilization in mice. The authors found that oral administration of nicotinamide riboside (NR) or nicotinamide mononucleotide (NMN) resulted in primary hepatic metabolism where they were converted into nicotinamide in the liver, failing to deliver intact NR or directly synthesize NAD in skeletal muscle via intact precursor uptake, unlike intravenous delivery. Because this evidence is derived from animal (mouse) metabolic tracer experiments, the GRADE certainty is very low for clinical translation to humans.

0:54:20Rhonda Patrick (host)supportedhigh

A clinical trial led by Doug Seals administering 1,000 mg of nicotinamide riboside daily raised blood NAD levels but did not produce statistically significant improvements in physiological vascular endpoints.

"This dose was like a thousand milligrams a day, and they looked at a variety of endpoints in addition to— ... Doug Seals' paper, yes. ... And there was no statistical significance in anything. It raised NAD levels, but there was no statistical significance. There was trending improvement in the vascular system, but there was no effect." (said at 0:54:20)

A 2018 randomized, double-blind, placebo-controlled crossover clinical trial conducted by Douglas Seals' laboratory (Martens et al., Nature Communications) evaluated oral nicotinamide riboside (1,000 mg/day, administered as 500 mg twice daily for 6 weeks) in healthy middle-aged and older adults. The trial confirmed that 1,000 mg/day of nicotinamide riboside was well tolerated and significantly elevated systemic NAD+ metabolism (by approximately 60%), but produced no statistically significant overall improvements in primary physiological cardiovascular/vascular endpoints, such as resting blood pressure or arterial stiffness, showing only non-significant exploratory trends in individuals with elevated baseline systolic blood pressure.

  • supports: Chronic nicotinamide riboside supplementation is well-tolerated and elevates NAD + in heal… (Nature communications 2018) · cited 591x in the literature
    "Here we provide the evidence in a 2 × 6-week randomized, double-blind, placebo-controlled, crossover clinical trial that chronic supplementation with the NAD + precursor vitamin, nicotinamide riboside (NR), is well tolerated and effectively stimulates NAD + metabolism in healthy middle-aged and older adults. Our results also provide initial insight into the effects of chronic NR supplementation on physiological function in humans, and suggest that, in particular, future clinical trials should further assess the potential benefits of NR for reducing blood pressure and arterial stiffness in this group." (abstract, results and conclusions, passage verified)
    pubmedfull study (doi)
1:01:41David Sinclairsupportedmoderate

Nicotinamide mononucleotide (NMN) is harder to synthesize than nicotinamide riboside because it is a larger molecule containing a phosphate group requiring difficult phosphate chemistry.

"NMN was late on the scene because it was harder to synthesize, because it's a bigger molecule, needs that phosphate, and phosphate chemistry is quite difficult." (said at 1:01:41)

Nicotinamide mononucleotide (NMN) is structurally a 5'-monophosphorylated form of nicotinamide riboside (NR), making it a larger molecule by the addition of a phosphate moiety. Chemical and biocatalytic synthesis of NMN requires phosphorylation of NR, which has historically presented significant synthetic and scalability challenges. Chemical phosphorylation requires aggressive phosphorus reagents (such as phosphorus oxychloride) and precise regioselective control, while enzymatic phosphorylation requires complex ATP-regeneration systems, making industrial NMN synthesis more technically challenging and costly than NR.

1:04:02David Sinclairsupportedlow

Nicotinamide mononucleotide (NMN) alters the epigenome and modulates the immune system.

"It definitely is changing the epigenome and immune system and stuff, but I agree, yeah." (said at 1:04:02)

Nicotinamide mononucleotide (NMN) acts as an essential precursor for nicotinamide adenine dinucleotide (NAD+), which serves as a co-substrate for NAD+-dependent enzymes including sirtuins (histone/protein deacetylases) and poly(ADP-ribose) polymerases. Preclinical and mechanistic studies demonstrate that NMN supplementation alters histone modifications (such as histone acetylation and methylation), remodels chromatin accessibility, and modulates immune and inflammatory signaling pathways (such as NF-κB and macrophage/T-cell activation). However, direct evidence of widespread epigenomic remodeling and immune modulation from human clinical trials remains preliminary.

1:07:49Rhonda Patrick (host)supportedmoderate

Developing children are more sensitive to evening light exposure than adults.

"developing children are really sensitive to light, even more sensitive than adults." (said at 1:07:49)

Experimental studies comparing children and adults demonstrate that developing children have significantly greater evening light sensitivity, experiencing approximately twice the melatonin suppression of adults at moderate light intensities. For example, exposure to moderately bright light (580 lux) suppressed salivary melatonin by 88.2% in school-aged children compared to 46.3% in adults, and typical domestic room lighting significantly suppressed melatonin in children but not in adults. Studies in preschool-aged children further show robust melatonin suppression (averaging 70–85%) across low-to-moderate evening light levels (as low as 5–40 lux) with prolonged recovery times.

1:09:44David Sinclairsupportedhigh

Existing medical treatments cannot reverse optic nerve damage and vision loss caused by glaucoma.

"glaucoma, which is a disease that's extremely hard to treat; you cannot reverse the damage that's been done" (said at 1:09:44)

The speaker's claim is supported. In clinical ophthalmology, glaucoma is defined as an optic neuropathy that causes irreversible visual field loss and optic nerve degeneration resulting from the death of retinal ganglion cells. All currently established and approved clinical treatments (including topical pressure-lowering medications, laser trabeculoplasty, and surgical interventions) aim to lower intraocular pressure to slow or halt further damage; they cannot regenerate dead ganglion cells or reverse vision loss that has already occurred.

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.