28 Supported by research
Saccharomyces cerevisiae (baker's yeast) cells have 16 linear chromosomes in their haploid state, or 32 when mated and diploid.
"They have 16 chromosomes, or 32 if they mate and fuse, and they actually function very similar to our own cells." (said at 0:03:37)
Published genomic literature confirms that the budding yeast Saccharomyces cerevisiae is a eukaryotic organism whose haploid nuclear genome consists of 16 linear chromosomes, possessing 32 telomeres. When haploid cells mate and fuse, the resulting diploid cell contains 32 chromosomes (16 homologous pairs).
Humans have seven sirtuin enzymes (SIRT1 through SIRT7), whereas yeast have five sirtuins.
"And now we know that these sirtuin enzymes—there are seven in our bodies, there are five in yeast, seven in ours, they're called SIRT1 to 7." (said at 0:06:44)
The statement accurately reflects established comparative biology and genetics. The human genome encodes seven sirtuin isoforms (designated SIRT1 through SIRT7), whereas the budding yeast (Saccharomyces cerevisiae) genome encodes five sirtuins: Sir2 and four homologues of Sir2 (Hst1, Hst2, Hst3, and Hst4).
Steve Horvath used machine learning on DNA methylation patterns across human tissues to develop a clock that correlates with chronological age.
"He used machine learning to develop a clock based on which of these methyl groups correlated with the age of many hundreds, now thousands of humans, um and he could draw a straight line" (said at 0:18:15)
Steve Horvath developed a multi-tissue epigenetic clock by applying penalized regression (an elastic net machine learning algorithm) to DNA methylation profiles from 8,000 human samples across 51 healthy tissues and cell types. The resulting algorithm, based on 353 specific CpG sites, accurately predicts chronological age across a wide range of human tissues and cell types.
Shinya Yamanaka and his team discovered that the combination of four transcription factors—Oct4, Sox2, Klf4, and c-Myc—can reprogram somatic cells into pluripotent stem cells.
"He and his team looked at many different combinations and hit upon a combination of four factors which are, of course, now known as uh Yamanaka factors, um and they're they're called Oct4, Sox2, Klf4, and c-Myc." (said at 0:20:15)
In 2006, Kazutoshi Takahashi and Shinya Yamanaka published their landmark discovery that somatic cells (mouse embryonic and adult fibroblasts) can be reprogrammed into induced pluripotent stem (iPS) cells using a combination of four defined transcription factors: Oct3/4 (Oct4), Sox2, Klf4, and c-Myc. This combination of four factors became widely known as the 'Yamanaka factors'.
Expressing all four Yamanaka reprogramming factors in vivo inside an animal can induce teratomas.
"Because you could easily end up with a cancer, a teratoma basically, cells growing out of growing like an embryo, but in the animal, which does happen actually if you turn on all of the Yamanaka factors." (said at 0:21:40)
Animal studies have demonstrated that continuous or unconstrained in vivo expression of all four Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc) drives somatic cell dedifferentiation and leads to widespread teratoma formation across multiple organs. Landmark work in reprogrammable transgenic mice showed that inducing the four Yamanaka factors resulted in multiple-organ teratomas, and managing teratoma risk remains a central safety challenge in in vivo reprogramming research.
- supports: Reprogramming in vivo produces teratomas and iPS cells with totipotency features. (Nature 2013) · cited 559x in the literature
"Here we show that transitory induction of the four factors Oct4, Sox2, Klf4 and c-Myc in mice results in teratomas emerging from multiple organs, implying that full reprogramming can occur in vivo." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Organ-Specific Dedifferentiation and Epigenetic Remodeling in In Vivo Reprogramming. (Aging cell 2025) · cited 6x in the literature
"Critical safety considerations-such as teratoma formation, organ failure, and loss of cell identity-are discussed alongside strategies designed to mitigate these risks, like cyclic induction and targeted delivery." (abstract, results, passage verified)
pubmedfull study (doi)
Ectopic expression of three Yamanaka factors (Oct4, Sox2, and Klf4) promotes optic nerve axon regeneration to the optic chiasm in mice after injury and reverses epigenetic aging markers.
"What we did in the other mouse was to turn on the three Yamanaka genes, O, S, and K, for three weeks and have a look what happened... You could see that the nerves were growing back towards the brain. In fact, if we leave them for 16 weeks, many of those nerves actually make it all the way back to where they meet the brain again, the chiasm, which is a first." (said at 0:26:30)
A 2020 study by Lu and colleagues (Nature) demonstrated that ectopic expression of three Yamanaka factors (Oct4, Sox2, and Klf4; OSK) delivered via an adeno-associated virus into mouse retinal ganglion cells restored youthful DNA methylation patterns, promoted axon regeneration following optic nerve crush injury, and enabled axons to extend toward the optic chiasm. Because the evidence is derived exclusively from preclinical mouse models, the GRADE certainty is very low.
Sirtuin enzymes require nicotinamide adenine dinucleotide (NAD) to carry out their deacetylation reaction.
"And the sirtuins, they don't work unless they have NAD. They have their own enzymatic reaction that absolutely requires NAD to work. It's called deacetylation, and that's how they control chromatin and the epigenome." (said at 0:28:42)
Sirtuins are defined biochemically as class III histone/protein deacetylases that strictly require nicotinamide adenine dinucleotide (NAD+) as a co-substrate to carry out their deacetylation and deacylation reactions. During catalysis, the enzyme cleaves NAD+ into nicotinamide and 2'-O-acetyl-ADP-ribose while removing acetyl groups from lysine residues on target proteins and histones, thereby regulating chromatin structure, epigenetic gene expression, and cellular metabolism.
Shin-ichiro Imai's research group demonstrated that overexpressing the sirtuin SIRT1 specifically in the brain/neurons of mice extends their lifespan.
"His team made a mouse where he turned on the sirtuin gene number one, SIRT1, in a mouse's neurons, and that mouse lived longer, which is great news." (said at 0:29:40)
A 2013 study led by Shin-ichiro Imai's laboratory demonstrated that brain-specific Sirt1-overexpressing (BRASTO) transgenic mice exhibited significant lifespan extension in both males and females, accompanied by delayed physiological aging phenotypes mediated by hypothalamic signaling. Because this finding is derived from transgenic animal models, the certainty of evidence for human longevity translation is very low.
Tissue injury or damage accelerates cellular aging as measured by the Horvath epigenetic DNA methylation clock.
"the damage accelerated aging according to the Horvath clock, which we didn't expect. I mean, who knew that damage would accelerate aging? But it does." (said at 0:26:48)
Preclinical experimental evidence demonstrates that tissue damage (such as optic nerve crush injury in mouse retinal ganglion cells) induces epigenetic alterations and accelerates DNA methylation age as measured by epigenetic clocks, an effect that can be reversed through OSK (Oct4, Sox2, Klf4) factor reprogramming. Because the direct experimental demonstration of damage-induced epigenetic aging acceleration is established in animal/cellular models, the certainty grade is very low.
Nicotinamide adenine dinucleotide (NAD) is an essential cofactor utilized in approximately 450 cellular chemical reactions.
"it's a small chemical that cells use for two reasons. One is it's used for 450 or so chemical reactions. Without it, we're dead probably in 20, 30 seconds." (said at 0:28:42)
Nicotinamide adenine dinucleotide (NAD+/NADH) is an essential coenzyme and electron carrier in cellular metabolism. It serves as a necessary cofactor for hundreds of enzymatic oxidation-reduction reactions (predominantly catalyzed by oxidoreductases across glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation) and acts as a substrate for signaling enzymes such as sirtuins, poly(ADP-ribose) polymerases (PARPs), and CD38.
- supports: Therapeutic Potential of NAD-Boosting Molecules: The In Vivo Evidence. (Cell metabolism 2018) · cited 870x in the literature
"Nicotinamide adenine dinucleotide (NAD), the cell's hydrogen carrier for redox enzymes, is well known for its role in redox reactions. More recently, it has emerged as a signaling molecule. By modulating NAD + -sensing enzymes, NAD + controls hundreds of key processes from energy metabolism to cell survival" (abstract, results, passage verified)
pubmedfull study (doi) - supports: Assays for NAD + -Dependent Reactions and NAD + Metabolites. (Methods in molecular biology (Clifton, N.J.) 2018) · cited 16x in the literature
"Nicotinamide adenine dinucleotide (NAD + ) is an essential redox cofactor and signaling molecule that controls the activity of enzymes involved in metabolism, DNA repair, and cellular survival, such as the PARPs, CD38, and the sirtuins." (abstract, results, passage verified)
pubmedfull study (doi)
Fasting and physical exercise increase intracellular NAD levels in humans.
"now in humans we know that when you're hungry or exercise, levels of NAD go up, and we hypothesize that they also protect the body." (said at 0:29:13)
Published human studies confirm that physical exercise activates nicotinamide phosphoribosyltransferase (NAMPT)—the rate-limiting enzyme in NAD+ biosynthesis—and increases intracellular NAD+ levels in human peripheral blood mononuclear cells and skeletal muscle. Nutrient deprivation and fasting also upregulate NAD+ salvage pathways and cellular NAD+ availability, though direct tissue quantification in humans is more extensively documented for physical exercise.
- supports: Healthy Lifestyle Recommendations: Do the Beneficial Effects Originate from NAD + Amount a… (Oxidative medicine and cellular longevity 2020) · cited 29x in the literature
"Namely, NAD + level can be regulated by lifestyle and nutrition approaches such as fasting, caloric restriction, sports activity, low glucose availability, and heat shocks." (abstract, passage verified)
pubmedfull study (doi) - supports: Exercise training upregulates intracellular nicotinamide phosphoribosyltransferase express… (Frontiers in public health 2023) · cited 9x in the literature
"Exercise training is effective for increasing iNAMPT levels in skeletal muscles. This essential enzyme regulates not only cellular energetics but also healthspan." (abstract, conclusions, passage verified)
pubmedfull study (doi) - supports: Acute exercise boosts NAD + metabolism of human peripheral blood mononuclear cells. (Brain, behavior, and immunity 2025) · cited 16x in the literature
"Nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of NAD + salvage pathway, displayed a pronounced increase in gene expression during exercise, which was accompanied by elevated intracellular NAD + levels and reduced serum levels of the NAD + precursor nicotinamide. These results demonstrate that acute exercise triggers NAD + biosynthesis of human PBMCs with potential implications for immunometabolism, immune effector function, and immunological exercise adaptions." (abstract, results, passage verified)
pubmedfull study (doi)
Sugar spikes suppress sirtuin enzyme activity.
"Sugar spikes will suppress your sirtuin activity, we think." (said at 0:31:47)
Preclinical in vitro and animal models demonstrate that high glucose exposure (hyperglycemia) downregulates the expression and catalytic activity of sirtuin enzymes, notably SIRT1, in part through altered cellular NAD+/NADH ratios and increased oxidative stress. Studies examining human cells (such as monocytes and neutrophils) exposed to high glucose or isolated from individuals with diabetes also show decreased SIRT1 expression and deacetylase activity compared to normoglycemic controls. However, direct real-time in vivo measurements of acute postprandial glucose spikes suppressing sirtuins across human tissues remain limited, aligning with the speaker's qualification ('we think'). Because the supporting evidence derives primarily from in vitro and animal models, the certainty is graded as very low.
- supports: Resveratrol up-regulates SIRT1 and inhibits cellular oxidative stress in the diabetic mili… (The Journal of nutritional biochemistry 2012) · cited 130x in the literature
"In T1DM patients, monocytic SIRT1 expression was significantly decreased and p47phox expression was increased compared with controls. Under HG in vitro, SIRT1 and FOXO3a were significantly decreased compared with NG, and this was reversed by resveratrol treatment, concomitant with reduction in HG-induced superoxide production and p47phox." (abstract, results, passage verified)
pubmedfull study (doi) - supports: High glucose induced alteration of SIRTs in endothelial cells causes rapid aging in a p300… (PloS one 2013) · cited 206x in the literature
"Data from this study demonstrated that hyperglycemia accelerates aging-like process in the vascular ECs and such process is mediated via downregulation of SIRT1, causing reduction of mitochondrial antioxidant enzyme in a p300 and FOXO1 mediated pathway." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Sirtuin 1 is an endogenous NETosis inhibitor that becomes dysfunctional in diabetes. (Journal of leukocyte biology 2026) · cited 3x in the literature
"Indeed, SIRT1 deacetylase activity was significantly lower in neutrophils of individuals with diabetes, accompanied by a concomitant increase in the activity of peptidylarginine deiminase 4 (PAD4), a key enzyme that mediates NETosis." (abstract, results, passage verified)
pubmedfull study (doi)
Clinical trials show that supplementing with NAD precursors NMN or NR can raise NAD levels approximately twofold in humans.
"The one that I take is called NMN. There's another one called NR, which are available as supplements. And in clinical trials, we've seen that that can raise NAD levels about twofold." (said at 0:32:18)
Multiple randomized, double-blind, placebo-controlled clinical trials demonstrate that oral supplementation with NAD precursors such as nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) dose-dependently elevates blood NAD+ concentrations in humans. Doses typically used in trials (e.g., 600 to 1,000 mg daily) produce roughly 1.5-fold to 2.5-fold (50% to >140%) increases in circulating NAD+ levels over baseline.
- supports: Nicotinamide riboside is uniquely and orally bioavailable in mice and humans. (Nature communications 2016) · cited 718x in the literature
"We report that human blood NAD + can rise as much as 2.7-fold with a single oral dose of NR in a pilot study of one individual, and that oral NR elevates mouse hepatic NAD + with distinct and superior pharmacokinetics to those of nicotinic acid and nicotinamide." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Safety and Metabolism of Long-term Administration of NIAGEN (Nicotinamide Riboside Chlorid… (Scientific reports 2019) · cited 218x in the literature
"Consumption of 100, 300 and 1000 mg NR dose-dependently and significantly increased whole blood NAD+ (i.e., 22%, 51% and 142%) and other NAD+ metabolites within 2 weeks." (abstract, results)
pubmedfull study (doi) - supports: MIB-626, an Oral Formulation of a Microcrystalline Unique Polymorph of β-Nicotinamide Mono… (The journals of gerontology. Series A, Biological sciences and medical sciences 2023) · cited 54x in the literature
"MIB-626 1 000 mg once-daily or twice-daily regimens were safe and associated with substantial dose-related increases in blood NAD levels and its metabolome." (abstract, conclusions, passage verified)
pubmedfull study (doi)
Marathon runners have resting NAD levels roughly 50% higher than untrained individuals.
"If you're a marathon runner, by the way, you probably only have NAD levels about 50% higher." (said at 0:32:35)
Cross-sectional human studies show that endurance-trained athletes and physically active individuals have elevated baseline NAD+ levels and biosynthetic capacity compared to sedentary or untrained controls. In human skeletal muscle and erythrocytes, regular exercise and endurance training are associated with higher basal NAD+ concentrations and up to a twofold increase in NAMPT, the rate-limiting enzyme in NAD+ biosynthesis.
- supports: Skeletal muscle NAMPT is induced by exercise in humans. (American journal of physiology. Endocrinology and metabolism 2010) · cited 299x in the literature
"A cross-sectional analysis of human subjects showed that athletes had about a twofold higher skeletal muscle NAMPT protein expression compared with sedentary obese, nonobese, and type 2 diabetic subjects (P < 0.05)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Exercise and ageing impact the kynurenine/tryptophan pathway and acylcarnitine metabolite … (The Journal of physiology 2023) · cited 38x in the literature
"Specifically, kynurenine was elevated in muscle from older adults, whereas downstream metabolites of kynurenine (kynurenic acid and NAD + ) were elevated in muscle from active adults and associated with cardiorespiratory fitness and muscle oxidative capacity." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Erythrocyte nicotinamide adenine dinucleotide concentration is enhanced by systematic spor… (BMC sports science, medicine & rehabilitation 2024) · cited 6x in the literature
"Erythrocyte concentrations of NAD+ and NADP+ were measured in 68 elite endurance runners (20-81 years), 58 elite sprinters (21-90 years), and 62 untrained individuals (20-68 years)... However, the concentration of erythrocyte NAD(P)+, regardless of age category, was higher in the athletic groups compared to less active controls." (abstract, results)
pubmedfull study (doi)
A 2013 Science paper showed that resveratrol directly activates the SIRT1 enzyme, and mutating a single amino acid in SIRT1 blocks this activation.
"we had a Science paper in 2013 that showed that resveratrol does activate the enzyme directly. This was controversial, but we showed it does, and you could mutate or change one amino acid in that enzyme and it blocked resveratrol's activity." (said at 0:33:18)
A 2013 study published in Science by Hubbard et al. demonstrated that sirtuin-activating compounds (STACs), including resveratrol, directly activate SIRT1 via an allosteric mechanism. The authors identified that a single amino acid residue in SIRT1 (Glu230) was critical for this activation, and mutating this residue blocked activation by resveratrol and other STAC scaffolds.
Mice genetically engineered to lack the specific SIRT1 amino acid required for resveratrol activation do not gain running endurance or health benefits from resveratrol on a high-fat diet.
"We've now made a mouse that lacks that one amino acid in the SIRT1 enzyme and given it resveratrol and a high-fat diet, and lo and behold, that mouse didn't respond to resveratrol. It couldn't run further; it wasn't healthy." (said at 0:33:48)
Research from the speaker's laboratory identified a specific amino acid in SIRT1 (Glu230 in humans, homologous to Glu222 in mice) that is required for direct allosteric activation by resveratrol and other sirtuin-activating compounds (STACs). In experimental models engineered with an activation-defective SIRT1 lacking this residue, the metabolic and mitochondrial benefits induced by STACs/resveratrol were blocked. Because the findings are based on preclinical cellular and rodent experimental models, the certainty of evidence is very low regarding broader translatability to human health.
Human skin samples show approximately 50% less NAD at age 50 compared to age 20 on average.
"If you take a skin sample, you have about 50% less at age 50 as you did when you were 20, on average." (said at 0:34:50)
A cross-sectional study evaluating human pelvic skin samples across ages (15–77 years plus newborns, n=49) demonstrated an age-dependent decline in NAD+ levels, showing strong negative correlations with age in both males (r = -0.706, p = 0.001) and females (r = -0.537, p = 0.01), with NAD+ concentrations declining by approximately 50% by middle age compared to young adulthood.
Oleic acid directly activates SIRT1 through the same mechanism and amino acid site as resveratrol.
"Doug Mashek published a paper last year, remarkable, that oleic acid works exactly the same way as resveratrol. And when you change this amino acid, it's not only blocking resveratrol and the drugs that were in clinical trials, but also oleic acid's activity." (said at 0:35:20)
A 2020 study from Doug Mashek's laboratory demonstrated that monounsaturated fatty acids (MUFAs), specifically oleic acid, directly and allosterically activate SIRT1. The study showed that oleic acid acts as an endogenous SIRT1-activating compound (STAC) via the N-terminal allosteric site of SIRT1 in a manner analogous to synthetic STACs and resveratrol, with mutations at this allosteric regulatory site disrupting activation. Because this evidence is derived from in vitro biochemical assays, cell cultures, and animal models, certainty is graded as very low.
Oleic acid is produced endogenously in the human body from the breakdown of white fat during fasting.
"it also turns out oleic acid is made in our bodies when we're hungry from the breakdown of white fat." (said at 0:35:51)
Oleic acid (an 18-carbon monounsaturated fatty acid) is the most abundant fatty acid stored in human white adipose tissue triglycerides. During periods of fasting, hunger, or negative energy balance, lipolysis is stimulated in white adipose tissue, leading to the enzymatic breakdown of stored triglycerides by lipases (such as adipose triglyceride lipase and hormone-sensitive lipase) and the subsequent release of free oleic acid into the systemic circulation.
A retrospective study of over 10,000 veterans with type 2 diabetes found that those taking metformin had reduced risk of cardiovascular disease, Alzheimer's, and frailty over four to five years compared to non-users.
"there are a couple of scientific papers that looked at over 10,000 people. There was there's one that looked over over 10,000 veterans who either did not take metformin or did. Okay, it's a prospective study—sorry, it's a retrospective study, so it's got some issues. But when you look at that data, it's really quite compelling because the people who took metformin for their type 2 diabetes—high blood sugar is what you typically are given metformin for—those patients, the risk of getting not just worse type 2 diabetes, but also if they were predisposed to cardiovascular disease or Alzheimer's or frailty, their risk went down." (said at 0:38:54)
A retrospective cohort study of 41,204 male US veterans aged 65 and older with type 2 diabetes (PMID 28190681) evaluated the association between metformin use and age-related comorbidities between 2004 and 2012. The study classified patients into distinct risk phenotypes (including high CVD risk, high cancer risk, high frailty risk, and healthy classes) and found that metformin use was associated with reduced likelihoods of cardiovascular disease, dementia, and frailty-related diseases across various risk groups compared to non-use. Because this evidence comes from an observational cohort subject to potential confounding by indication and survivor bias, the certainty is low.
Exercise is a powerful activator of the AMP-activated protein kinase (AMPK) pathway.
"exercise is also a powerful activator of the AMP kinase pathway." (said at 0:40:56)
Extensive physiological and biochemical research establishes that exercise and muscle contraction are major physiological activators of AMP-activated protein kinase (AMPK). Increased cellular AMP-to-ATP and ADP-to-ATP ratios during muscle contraction trigger AMPK phosphorylation, which coordinates downstream metabolic pathways including glucose uptake, fatty acid oxidation, and mitochondrial biogenesis.
A study found that people who engaged in high amounts of cycling had their overall mortality risk reduced by 40% in later decades of life.
"There is one study where people who cycled a lot—and the number, David, I can't remember exactly, but it was quite a lot, let's say 40 miles a day, something like that—their risk, overall mortality risk, went down by 40% in their later decades" (said at 0:41:26)
Large prospective observational studies have found an approximate 40% reduction in all-cause mortality risk associated with routine cycling. In the Copenhagen City Heart Study of over 30,000 adults followed for an average of 14.5 years, bicycling to work was associated with an approximate 40% reduction in all-cause mortality after multivariate adjustment. Similarly, a large UK Biobank prospective cohort study of 263,450 participants found that cycle commuting was associated with a 41% lower risk of all-cause mortality (hazard ratio 0.59). Although the speaker was uncertain about the exact volume (estimating 40 miles a day), the 40% mortality risk reduction figure accurately reflects published cohort data.
- supports: All-cause mortality associated with physical activity during leisure time, work, sports, a… (Archives of internal medicine 2000) · cited 1046x in the literature
"Bicycling to work decreased risk of mortality in approximately 40% after multivariate adjustment, including leisure time physical activity." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Association between active commuting and incident cardiovascular disease, cancer, and mort… (BMJ (Clinical research ed.) 2017) · cited 527x in the literature
"In maximally adjusted models, commuting by cycle and by mixed mode including cycling were associated with lower risk of all cause mortality (cycling hazard ratio 0.59, 95% confidence interval 0.42 to 0.83, P=0.002; mixed mode cycling 0.76, 0.58 to 1.00, P<0.05)" (abstract, results, passage verified)
pubmedfull study (doi)
A published study showed that repletion with 600 to 2,000 IU/day of vitamin D altered Horvath epigenetic clock aging measurements in overweight African Americans with low vitamin D levels.
"There was one recent publication, I believe it was last year in October, looking at overweight African Americans, and the only intervention in those who had low vitamin D levels was to at various levels replete their vitamin D—I think it was 600 up to 2,000 IU a day—and demonstrated, in fact, changes in I think it was the velocity or the rate of change of the Horvath clock, or it may have been the delta between chronologic age versus the Horvath age." (said at 0:46:01)
A 16-week randomized controlled trial by Chen et al. evaluated vitamin D3 supplementation (600, 2,000, or 4,000 IU/day vs. placebo) in overweight and obese African Americans with suboptimal vitamin D status (serum 25(OH)D < 50 nmol/L). The trial analyzed epigenetic aging using both the Horvath and Hannum DNA methylation clocks (measuring the age acceleration index, defined as the difference between DNA methylation age and chronological age). The researchers found that higher-dose vitamin D supplementation (4,000 IU/day) significantly reduced Horvath epigenetic age acceleration by 1.85 years compared to placebo (p = 0.046), and increasing serum 25(OH)D concentrations across participants were significantly associated with reduced Horvath age acceleration (p = 0.002).
- supports: Effects of Vitamin D3 Supplementation on Epigenetic Aging in Overweight and Obese African … (The journals of gerontology. Series A, Biological sciences and medical sciences 2019) · cited 130x in the literature
"A randomized clinical trial was previously conducted among 70 overweight/obese African Americans with serum 25-hydroxyvitamin D [25(OH)D] < 50 nmol/L, who were randomly assigned into four groups of 600 IU/d, 2,000 IU/d, 4,000 IU/d of vitamin D3 supplements or placebo followed by 16-week interventions. Whole genome-wide DNA methylation analysis was conducted in 51 participants. DNA methylation ages were calculated according to the Horvath and the Hannum methods. Methylation-based age acceleration index (∆Age) is defined as the difference between DNA methylation age and chronological age in years... After the adjustment of multi-covariates, vitamin D3 supplementation of 4,000 IU/d was associated with 1.85 years decrease in Horvath epigenetic aging compared with placebo (p value = .046)... Serum 25(OH)D concentrations were significantly associated with decreased Horvath ∆Age only (p values = .002), regardless of treatments." (abstract, methods and results, passage verified)
pubmedfull study (doi)
Manuel Serrano published a study demonstrating that cellular reprogramming in the brains of old mice resulted in restored neurogenesis and memory.
"There was a recent study by my colleague Manuel Serrano who reprogrammed the brain of old mice and got neurogenesis and memory back." (said at 0:51:47)
A 2020 study co-authored by Manuel Serrano and colleagues (Rodríguez-Matellán et al.) demonstrated that transient cyclic in vivo expression of Yamanaka reprogramming factors in aged mice ameliorated aging hallmarks in the dentate gyrus. This intervention increased levels of neurogenic markers (doublecortin and calretinin, suggesting enhanced neurogenesis and survival of newborn dentate gyrus neurons) and improved cognitive performance in memory tests (novel object recognition). Because the evidence is derived exclusively from preclinical rodent models, certainty is graded as very low.
Treating mice systemically or ocularly with three Yamanaka factors over a year showed no evidence of increased cancer incidence.
"these three genes, even though we pumped the mouse full of them, either just in the eye or the whole mouse, there was no sign over a year of any increased cancer." (said at 0:52:08)
In a landmark 2020 preclinical study by Lu et al. (Nature), researchers investigated the safety and efficacy of expressing three Yamanaka factors—Oct4, Sox2, and Klf4 (OSK), omitting the oncogene c-Myc—delivered via adeno-associated viral (AAV) vectors either intraocularly or systemically (intravenously) in mice. Continuous expression of OSK for up to 10 to 15 months showed no evidence of increased tumor formation, dysplasia, or negative histological changes. However, as this evidence is restricted entirely to animal models, the certainty is graded as very low.
Consuming red meat, lamb, and eggs stimulates the mTOR pathway due to specific amino acids they contain.
"We know that red meat, things like beef and as well lamb and eggs, have certain types of amino acids that will go ahead and stimulate the mTOR pathway" (said at 0:58:30)
Animal proteins such as beef, lamb, and eggs are rich sources of essential amino acids—most notably the branched-chain amino acid leucine—which act as primary nutritional activators of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway. In human skeletal muscle, postprandial availability of these specific amino acids triggers mTORC1 translocation and phosphorylation cascades that drive muscle protein synthesis.
- supports: Leucine ingestion promotes mTOR translocation to the periphery and enhances total and peri… (Amino acids 2023) · cited 22x in the literature
"The activation of the mechanistic target of rapamycin complex 1 (mTORC1), a master regulator of protein synthesis, by anabolic stimuli (such as muscle contraction or essential amino acids) involves its translocation to the cell periphery. Leucine is generally considered the most anabolic of amino acids for its ability to independently modulate muscle protein synthesis." (abstract, passage verified)
pubmedfull study (doi) - supports: A focus on leucine in the nutritional regulation of human skeletal muscle metabolism in ag… (Clinical nutrition (Edinburgh, Scotland) 2023) · cited 58x in the literature
"Following consumption of dietary protein, the bio-availability of essential amino acids (EAA), and primarily leucine (LEU), drive a transient increase in MPS with an ensuing refractory period before the next MPS stimulation is possible... Of all the EAA, LEU is the most potent stimulator of the mechanistic target of rapamycin complex 1 (mTORC1)-signalling pathway, with the phosphorylation of mTORC1 substrates increasing ∼3-fold more than with all other EAA." (abstract, passage verified)
pubmedfull study (doi)
Administering resveratrol to obese mice fed a high-fat diet extends their lifespan and improves overall health.
"We then showed that you could give resveratrol to old and fat mice, and it helped them. They lived longer. They were healthier." (said at 0:33:22)
A landmark 2006 study by Baur and colleagues demonstrated that administering resveratrol to middle-aged mice fed a high-calorie diet significantly improved survival and several markers of metabolic and functional health compared to control mice on the high-calorie diet. Resveratrol-treated mice exhibited increased insulin sensitivity, decreased IGF-1 levels, higher mitochondrial count, and improved motor function, shifting their physiology toward that of mice on a standard diet. Because the finding is derived exclusively from rodent models, the overall clinical certainty 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-activated receptor-gamma coactivator 1alpha (PGC-1alpha) activity, increased mitochondrial number, and improved motor function." (abstract, results, passage verified)
pubmedfull study (doi)
Delivery of three Yamanaka reprogramming factors via adeno-associated virus can regenerate the optic nerve and restore vision in mice.
"regrow the optic nerve if you do what we did." (said at 0:52:38)
A landmark 2020 study by Lu et al. demonstrated that ectopic expression of three Yamanaka transcription factors (Oct4, Sox2, and Klf4, or OSK) delivered via an adeno-associated viral (AAV) vector promoted optic nerve axon regeneration following crush injury in mice. The treatment also restored visual function in mouse models of glaucoma and in naturally aged mice. Because the evidence is derived exclusively from animal models, the GRADE certainty is very low for clinical translation to humans.
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.