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The Horvath pan-tissue epigenetic clock measures age across all tissues and cells containing DNA, from prenatal samples to supercentenarians over 110 years old.
"The Horvath aging clock is what I sometimes call the so-called pan-tissue epigenetic clock. And so it is the most accurate molecular measure of age. It applies to all cells in the bodies, certainly all cells that have DNA, all tissues, all organs. It measures age in prenatal samples, in children, all the way to supercentenarians, people who are over 110 years old." (said at 0:00:46)
The statement accurately reflects the design, capabilities, and published validation of the Horvath pan-tissue epigenetic clock (Horvath 2013). Steve Horvath developed a multi-tissue predictor based on 353 CpG sites across 51 healthy tissues and cell types using 8,000 samples. The clock successfully estimates DNA methylation age across human development and the lifespan—demonstrating near-zero age in prenatal/embryonic and induced pluripotent stem cells, accurate prediction in children and adults, and applicability extending to semi-supercentenarians and supercentenarians aged 110 and older across diverse human tissues containing DNA.
- supports: DNA methylation age of human tissues and cell types. (Genome biology 2013) · cited 7501x in the literature
"I developed a multi-tissue predictor of age that allows one to estimate the DNA methylation age of most tissues and cell types. The predictor, which is freely available, was developed using 8,000 samples from 82 Illumina DNA methylation array datasets, encompassing 51 healthy tissues and cell types. I found that DNA methylation age has the following properties: first, it is close to zero for embryonic and induced pluripotent stem cells; second, it correlates with cell passage number; third, it gives rise to a highly heritable measure of age acceleration; and, fourth, it is applicable to chimpanzee tissues." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Centenarian clocks: epigenetic clocks for validating claims of exceptional longevity. (GeroScience 2023) · cited 48x in the literature
"The three centenarian clocks were developed based on n = 7039 blood and saliva samples from individuals older than 40, including n = 184 samples from centenarians, 122 samples from semi-supercentenarians (aged 105 +), and 25 samples from supercentenarians (aged 110 +). The oldest individual was 115 years old." (abstract, results, passage verified)
pubmedfull study (doi)
People of Hispanic ancestry age more slowly according to the epigenetic clock despite having higher clinical risk profiles for diabetes and metabolic syndrome.
"And the number one example I want to mention in this context are actually people of Hispanic ancestry. Unfortunately, Hispanics often have higher risk for diabetes, higher metabolic syndrome, and however, according to the epigenetic clock, they actually age more slowly, you know. And so this is really this disconnect. And this is actually an interesting disconnect because there's something known as a Hispanic mortality paradox, you know." (said at 0:05:00)
The claim accurately reflects findings from epigenetic clock research examining racial and ethnic differences in biological aging. In a landmark 2016 study led by Steve Horvath (PMID: 27511193), blood and tissue samples across diverse ethnic cohorts demonstrated that individuals of Hispanic ancestry exhibit significantly lower intrinsic epigenetic aging rates (epigenetic age acceleration independent of immune cell composition) compared to non-Hispanic Caucasians. This slower intrinsic biological aging was identified as a potential molecular explanation for the 'Hispanic mortality paradox,' in which Hispanic populations often experience lower all-cause mortality and longer life expectancy despite elevated clinical risk profiles for type 2 diabetes and metabolic syndrome.
Offspring of centenarians exhibit slower epigenetic aging in blood compared to age-matched controls whose parents did not live to age 100.
"So if you have a parent who lived until age 100 or 105, then chances are that your blood is actually younger than the blood of a person of the same age, same gender, same everything, but whose parents didn't live until age 100, you know. So the offspring of centenarians obviously have a genetic advantage hopefully, but also that is manifested in the epigenetic clock." (said at 0:08:40)
Observational studies measuring DNA methylation age in blood have demonstrated that offspring of exceptionally long-lived individuals (semi-supercentenarians and centenarians) exhibit a lower epigenetic age compared to age-matched controls without familial longevity. For instance, an analysis of peripheral blood mononuclear cells (PBMCs) found that offspring of semi-supercentenarians had an epigenetic age approximately 5.1 years younger than age-matched controls (p = 0.00043).
Longitudinal epidemiological data show that individual rates of epigenetic aging remain consistent over multiple decades.
"And so you can then ask the question whether a person who was aging quickly at the first blood draw, did they still age quickly at the second blood draw, you know. And the answer is yes. And conversely, you observe the same for people who age more slowly, you know." (said at 0:09:14)
Longitudinal cohort data confirm that individual differences in epigenetic aging (the discrepancy between DNA methylation age and chronological age, or age acceleration) remain consistent and heritable over time across repeated measures. In longitudinal studies tracking individuals across cohorts over multiple years, individuals with positive epigenetic age acceleration (biological age exceeding chronological age) or negative age acceleration maintain their relative pace of aging across successive timepoints.
The Horvath pan-tissue epigenetic clock is based on 353 specific DNA methylation sites in the genome.
"For example, the pan-tissue clock is based on 353 locations in the genome." (said at 0:13:50)
Steve Horvath's landmark 2013 publication establishing the multi-tissue (pan-tissue) epigenetic clock demonstrated that the age predictor was constructed using 353 specific CpG DNA methylation sites across human tissues and cell types.
The DNA methylation GrimAge biomarker predicts time to coronary heart disease.
"And you mentioned heart disease; GrimAge is a pretty good predictor of time to coronary heart disease." (said at 0:16:20)
DNA methylation GrimAge was developed as a composite epigenetic biomarker of mortality and morbidity risk based on DNA methylation surrogates of plasma proteins and smoking pack-years. In large-scale validation cohorts comprising thousands of participants, GrimAge was demonstrated to significantly predict time-to-coronary heart disease (Cox regression P = 6.2 × 10⁻²⁴) as well as time-to-death and time-to-cancer.
Blood DNA methylation biomarkers, such as GrimAge, statistically predict future onset of cancer.
"biomarkers such as GrimAge and other biomarkers actually do predict onset to cancer in a statistical fashion, you know. The p-value would be quite significant." (said at 0:17:20)
Prospective cohort studies demonstrate that DNA methylation (DNAm) age acceleration biomarkers, including DNAm GrimAge and PhenoAge, statistically predict future cancer incidence. Initial validation of DNAm GrimAge showed a strong prospective association with time-to-cancer diagnosis (P = 1.3 × 10⁻¹²). Subsequent prospective cohort analyses confirmed that higher GrimAge acceleration is associated with an increased overall risk of cancer (e.g., rate ratio per standard deviation = 1.12, 95% CI: 1.05–1.20) as well as specific cancer types, particularly lung cancer.
Blood samples from Parkinson's disease patients show a slight epigenetic age acceleration of 1 to 2 years.
"Yes, so we looked at blood samples from Parkinson's cases and controls, and there's no question there's an age acceleration effect in blood. It's minor, it's one or two years, you know, but it is there." (said at 0:18:56)
Published case-control studies analyzing DNA methylation in peripheral blood samples from Parkinson's disease (PD) patients and healthy controls have demonstrated a modest, statistically significant increase in epigenetic age acceleration (around 1 to 2 years) in PD cases compared to controls. This includes increases in both intrinsic (independent of cell counts) and extrinsic (associated with immune cell composition changes) epigenetic age acceleration. Certainty is rated as low due to the observational case-control design and cross-sectional nature of the primary measurement.
Alzheimer's disease cases show epigenetic age acceleration in the prefrontal cortex.
"Alzheimer's disease, we looked at prefrontal cortex samples from the Religious Orders Study, you know, and again, we found age acceleration in the prefrontal cortex." (said at 0:19:16)
Analysis of dorsolateral prefrontal cortex samples from 700 participants in the Religious Orders Study and the Rush Memory and Aging Project demonstrated that epigenetic age acceleration in the prefrontal cortex was positively correlated with neuropathological hallmarks of Alzheimer's disease (including diffuse plaques, neuritic plaques, and amyloid load) and associated with accelerated cognitive decline.
- supports: Epigenetic age of the pre-frontal cortex is associated with neuritic plaques, amyloid load… (Aging 2015) · cited 484x in the literature
"Here we use n=700 dorsolateral prefrontal cortex (DLPFC) samples from Caucasian subjects of the Religious Order Study and the Rush Memory and Aging Project to examine the association between epigenetic age and Alzheimer's disease (AD) related cognitive decline, and AD related neuropathological markers. Epigenetic age acceleration of DLPFC is correlated with several neuropathological measurements including diffuse plaques (r=0.12, p=0.0015), neuritic plaques (r=0.11, p=0.0036), and amyloid load (r=0.091, p=0.016)." (abstract, results, passage verified)
pubmedfull study (doi)
Malignant breast tissue in luminal breast cancer exhibits 10 to 15 years of epigenetic age acceleration.
"So if I, for example, when I analyzed malignant breast tissue samples from women with so-called luminal breast cancer, the epigenetic age acceleration is off the chart. So their breast tissue is much older than expected, but it's complicated." (said at 0:20:25)
The speaker claims that when analyzing malignant breast tissue samples from women with luminal breast cancer, significant epigenetic age acceleration is observed (making the breast tissue look much older than expected). Published molecular studies using DNA methylation epigenetic clocks (such as Horvath's clock) confirm that malignant breast tissues, and specifically luminal breast cancer subtypes (which are estrogen receptor positive), exhibit significant epigenetic age acceleration compared to adjacent non-tumor breast tissue or normal tissues (PMID: 36991516). Studies also show that normal adjacent breast tissue in luminal breast cancer patients and healthy female breast tissue show epigenetic age acceleration relative to chronological age or matched peripheral blood (PMID: 30157950, PMID: 28364215).
Parkinson's disease patients have highly elevated neutrophil counts in blood.
"However, my software also produces estimates of blood cell counts, and so it turned out that the blood cell counts, in particular neutrophils, were really highly elevated in Parkinson's disease—huge effect, you know. And so in certain ways, this was completely surprising to me, but this finding has now been validated over and over. So yes, PD cases have highly elevated neutrophil counts." (said at 0:21:49)
Published literature supports the claim that Parkinson's disease (PD) patients exhibit significantly elevated peripheral blood granulocyte/neutrophil counts and elevated neutrophil-to-lymphocyte ratios (NLR) compared to healthy controls. DNA methylation-based blood cell deconvolution studies initially identified significant elevations in granulocytes among PD cases across distinct cohorts, and subsequent systematic reviews and meta-analyses have consistently confirmed significantly higher neutrophil counts and NLR in patients with PD.
- supports: Increased epigenetic age and granulocyte counts in the blood of Parkinson's disease patien… (Aging 2015) · cited 487x in the literature
"We find striking differences in imputed blood cell counts between PD cases and controls. Compared to control subjects, PD subjects contains more granulocytes (p=1.0 x 10(-9) in Caucasians, p=0.00066 in Hispanics) but fewer T helper cells" (abstract, results, passage verified)
pubmedfull study (doi) - supports: Peripheral Immune Profile and Neutrophil-to-Lymphocyte Ratio in Parkinson's Disease. (Movement disorders : official journal of the Movement Disorder Society 2021) · cited 102x in the literature
"PD patients had an altered peripheral immune profile and a higher NLR compared with HCs." (abstract, conclusions, passage verified)
pubmedfull study (doi) - supports: Neutrophil to lymphocyte ratio in parkinson's disease: a systematic review and meta-analys… (BMC neurology 2023) · cited 43x in the literature
"A random-effect model revealed that PD patients had elevated NLR values compared to healthy individuals (SMD = 0.81, 95% CI = 0.47 to 1.14, P < 0.001)." (abstract, results, passage verified)
pubmedfull study (doi)
Epigenetic clocks such as GrimAge and PhenoAge correlate weakly with telomere length at approximately r = 0.1.
"They um so they would have a weak correlation with telomere length—to give you a number, correlation 0.1. So it's actually a weak correlation, but yes, if you have a thousand people, you pick it up, you know." (said at 0:25:04)
Published cohort studies comparing cellular and biological markers of aging confirm that DNA methylation-based epigenetic clocks (including GrimAge and PhenoAge) correlate weakly or modestly with leukocyte telomere length. While both reflect aspects of biological aging, their association is typically low (with unadjusted and age-adjusted correlation coefficients generally in the range of r = -0.1 to -0.3), demonstrating that epigenetic clocks and telomere shortening capture distinct, largely independent biological aging pathways.
- supports: Longitudinal trajectories, correlations and mortality associations of nine biological ages… (eLife 2020) · cited 427x in the literature
"All BAs were correlated to varying degrees; correlations were mostly explained by CA. Individually, all BAs except for telomere length were associated with mortality risk independently of CA. The largest effects were seen for methylation age estimators (GrimAge) and the frailty index (FI)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Telomere length and epigenetic clocks as markers of cellular aging: a comparative study. (GeroScience 2022) · cited 61x in the literature
"LTL showed statistically significant negative correlations with all clocks (qPCR: r = - 0.26 to - 0.32; flow FISH: r = - 0.34 to - 0.49; p < 0.001 for all). Yet, models adjusted for age, sex, and race revealed significant associations between three of five clocks (PhenoAge, GrimAge, and Hannum clocks) and LTL by flow FISH (p < 0.01 for all) or qPCR (p < 0.001 for all)... The observed modest correlations between LTL and epigenetic clocks highlight a possible benefit from incorporating both measures in understanding disease etiology and prognosis." (abstract, results, passage verified)
pubmedfull study (doi)
Physical activity has a very weak correlation with epigenetic aging in blood, around r = 0.08.
"And physical activity, yeah, is exactly unfortunately weak. So I want to say correlation 0.08, for people who know what that means. That's a very weak correlation." (said at 0:28:44)
Published analyses of blood-based DNA methylation (epigenetic) clocks consistently show very weak correlations between self-reported physical activity and epigenetic age acceleration measures (typically |r| < 0.10). Because early standard blood epigenetic clocks (such as the Horvath and Hannum clocks) captured lifestyle factors like smoking and BMI much more strongly than physical fitness, specialized indicators (such as DNAmFitAge) were later constructed to better capture exercise and physical function phenotypes.
- supports: Epigenetic clock analysis of diet, exercise, education, and lifestyle factors. (Aging 2017) · cited 901x in the literature
"Extrinsic epigenetic age acceleration (EEAA) exhibits significant associations with fish intake (p=0.02), moderate alcohol consumption (p=0.01), education (p=3x10 -5 ), BMI (p=0.01), and blood carotenoid levels (p=1x10 -5 )-an indicator of fruit and vegetable consumption, whereas intrinsic epigenetic age acceleration (IEAA) is associated with poultry intake (p=0.03) and BMI (p=0.05)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: DNAmFitAge: biological age indicator incorporating physical fitness. (Aging 2023) · cited 101x in the literature
"However, current epigenetic clocks did not yet use measures of mobility, strength, lung, or endurance fitness in their construction. We develop blood-based DNAm biomarkers for fitness parameters gait speed (walking speed), maximum handgrip strength, forced expiratory volume in one second (FEV1), and maximal oxygen uptake (VO2max) which have modest correlation with fitness parameters in five large-scale validation datasets (average r between 0.16-0.48)." (abstract, results, passage verified)
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Obesity significantly accelerates epigenetic aging in liver tissue.
"Turns out obese people age faster in blood; however, the strongest effect can be found in liver tissue. So obesity greatly accelerates the epigenetic age of liver tissue, you know." (said at 0:29:13)
Published epigenetic clock analyses demonstrate a significant relationship between obesity/BMI and accelerated DNA methylation age in human liver tissue. In a landmark multi-tissue study evaluating blood, liver, muscle, and adipose tissue, elevated body mass index (BMI) showed a strong and statistically significant correlation with epigenetic age acceleration in the liver (increasing biological age by approximately 3.3 years per 10 BMI units).
Postmenopausal hormone therapy does not slow epigenetic aging in blood, but significantly slows epigenetic aging in buccal epithelial cells.
"So for example, when we evaluated the effect of postmenopausal hormone therapy in women, we found no beneficial effect in blood. However, interestingly, the buccal epithelial cells, so the cells inside of your mouth, they actually revealed that women who took hormone therapy were aging more slowly in these cells, you know." (said at 0:29:38)
A large multi-cohort study analyzing epigenetic clocks across blood, saliva, and buccal epithelium (including cohorts such as the Women's Health Initiative and the MRC National Survey of Health and Development) evaluated the association between menopausal hormone therapy and DNA methylation age. The researchers found that menopausal hormone therapy was not associated with reduced epigenetic age acceleration in blood, but was significantly associated with a lower epigenetic age in buccal epithelial cells (P = 0.00078).
Semi-supercentenarians aged around 105 years have an epigenetic age that is approximately 8.6 years younger than their chronological age.
"Because I recall from looking at the epigenetic clock of these semi-supercentenarians, people that are like 105 years old, they had epigenetic aging clocks that were like 8.6 years younger than— GUEST1: Yeah, that's true. That's the manifestation of that." (said at 0:08:40)
A landmark 2015 study by Horvath et al. evaluated DNA methylation in peripheral blood mononuclear cells from 82 Italian semi-supercentenarians (mean age 105.6 ± 1.6 years), their offspring, and controls. Using the Horvath epigenetic clock, the researchers found that these semi-supercentenarians had an epigenetic age that was on average 8.6 years younger than expected based on their chronological age.
- supports: Decreased epigenetic age of PBMCs from Italian semi-supercentenarians and their offspring. (Aging 2015) · cited 338x in the literature
"We analyze the DNA methylation levels of peripheral blood mononuclear cells (PBMCs) from Italian families constituted of 82 semi-supercentenarians (mean age: 105.6 ± 1.6 years), 63 semi-supercentenarians' offspring (mean age: 71.8 ± 7.8 years), and 47 age-matched controls (mean age: 69.8 ± 7.2 years). We demonstrate that the offspring of semi-supercentenarians have a lower epigenetic age than age-matched controls (age difference=5.1 years, p=0.00043) and that centenarians are younger (8.6 years) than expected based on their chronological age." (abstract, results, passage verified)
pubmedfull study (doi)
Telomere length exhibits a U-shaped relationship with health risks, where having telomeres that are either excessively short or excessively long is disadvantageous.
"And so, as you said, by now we know that there is a U-shape behavior: you don't want telomeres that are too short, and you don't want to have telomeres that are too long, you know." (said at 0:23:06)
Epidemiological and Mendelian randomization studies support a non-linear or U-shaped relationship between telomere length and health risks. Having very short telomeres is associated with increased risks of degenerative conditions (such as cardiovascular disease, pulmonary fibrosis, and cellular senescence), whereas excessively long telomeres are linked to an increased risk of multiple malignancies (such as melanoma, glioma, and other cancers) due to extended cellular proliferative capacity. Prospective cohort data also demonstrate a U-shaped relationship between leukocyte telomere length and all-cause as well as cancer-related mortality, with individuals in the middle range having the lowest mortality risk.
- supports: U-Shaped Relationship of Leukocyte Telomere Length With All-Cause and Cancer-Related Morta… (The journals of gerontology. Series A, Biological sciences and medical sciences 2021) · cited 16x in the literature
"There was a U-shaped association of LTL with all-cause mortality. Men with T/S ratio in the middle quartiles had lower mortality (quartiles, Q2 vs Q1, hazard ratio [HR] = 0.86, 95% confidence interval [CI] 0.77-0.97, p = .012; Q3 vs Q1 HR = 0.88, CI 0.79-0.99, p = .032). ... In older men, both shorter and longer LTL are associated with all-cause mortality. A similar U-shaped association was seen with cancer deaths" (abstract, results and conclusions, passage verified)
pubmedfull study (doi) - supports: Are long telomeres better than short? Relative contributions of genetically predicted telo… (PloS one 2020) · cited 31x in the literature
"Mendelian Randomization (MR) studies exploiting single nucleotide polymorphisms (SNPs) predictive of leukocyte telomere length (LTL) have suggested that shorter genetically determined telomere length (gTL) is associated with increased risks of degenerative diseases, including cardiovascular and Alzheimer's diseases, while longer gTL is associated with increased cancer risks." (abstract, background, passage verified)
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Certain inherited genetic variants accelerate epigenetic aging in blood without causing accelerated aging in brain tissue.
"some people um inherit a genetic variant that accelerates the epigenetic age in blood, but not really in in brain tissue, you know." (said at 0:31:23)
Large-scale genome-wide association studies (GWAS) of epigenetic aging rates have identified specific inherited genetic variants (most notably in the telomerase reverse transcriptase gene, TERT) that significantly accelerate epigenetic aging in blood (intrinsic and extrinsic epigenetic age acceleration) while having distinct, tissue-specific effects that do not similarly accelerate epigenetic aging across post-mitotic tissues such as the brain.
Following hematopoietic stem cell transplantation, reconstituted blood retains the epigenetic age of the donor rather than the recipient for decades.
"there are now several scientific papers that really give an unequivocal answer, and which is the reconstituted blood in the recipient has the age of the donor, you know. And that effect persists for decades, you know." (said at 0:33:16)
Multiple studies evaluating DNA methylation age following allogeneic hematopoietic stem cell transplantation (HSCT) have demonstrated that the epigenetic clock of the reconstituted recipient blood reflects the age of the donor rather than the recipient. Long-term follow-up has shown that this cell-intrinsic donor DNA methylation age persists for up to 17 to 20 years post-transplant in non-relapsed recipients, though more recent data indicate subtle environmental modulation by the host body over time.
In heterochronic parabiosis, young mice surgically joined to old mice exhibit accelerated epigenetic aging in brain tissues according to mouse epigenetic clocks.
"we looked at cortex and also subventricular zone, deep white matter in the brain, and we found that mice that were A young mouse that was connected to an old mouse actually aged faster according to an epigenetic clock in mice." (said at 0:35:33)
Preclinical mouse studies confirm that pairing a young mouse with an aged partner via heterochronic parabiosis increases the young mouse's biological and epigenetic age across tissues, as assessed by mouse DNA methylation clocks. This acceleration in biological age has also been shown to be transient and reversible after surgical detachment. Because the evidence comes exclusively from animal models, the certainty grade is very low.
Epigenetic clocks function accurately to measure age in post-mitotic neurons.
"the epigenetic clocks work beautifully in neurons, you know, which really don't rejuvenate over the lifespan, you know." (said at 0:38:40)
Epigenetic clocks reliably track chronological and biological age in post-mitotic human brain cells, including sorted neuronal populations. Studies profiling DNA methylation across human lifespans demonstrate that age remains a primary predictor of methylation changes in neurons and that both pan-tissue and cell-type-specific epigenetic clocks accurately quantify age and biological aging processes in these non-dividing cells.
- supports: Human brain aging is associated with dysregulation of cell type epigenetic identity. (GeroScience 2025) · cited 8x in the literature
"Addressing the limitations of previous research due to the limited number of investigated CpGs and the heterogeneous nature of tissue samples, here, we have examined DNA methylation of over 20 million CpGs across a broad age span in neurons and non-neuronal cells, primarily oligodendrocytes. We show that aging is a primary predictor of DNA methylation variation, surpassing the influence of factors such as sex and schizophrenia diagnosis, among others." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Cell-type specific epigenetic clocks to quantify biological age at cell-type resolution. (Aging 2024) · cited 30x in the literature
"Using brain and liver tissue as prototypes, we build and validate neuron and hepatocyte specific DNA methylation clocks, and demonstrate that these cell-type specific clocks yield improved estimates of chronological age in the corresponding cell and tissue-types." (abstract, results, passage verified)
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HIV infection is associated with accelerated epigenetic aging in humans.
"our finding that HIV is very much associated with accelerated epigenetic aging also points again to this idea of a viral component, you know." (said at 0:44:57)
Multiple longitudinal studies and a systematic review confirm that HIV infection is significantly associated with accelerated epigenetic aging in human blood and other tissues, as measured by various DNA methylation clocks (e.g., Horvath, Hannum, Levine/PhenoAge, and GrimAge). This epigenetic age acceleration is detectable from the time of initial infection.
Direct transdifferentiation of somatic skin cells into neurons preserves the original epigenetic age of the donor skin cells.
"So you take, for example, a skin cell and you add certain factors, maybe microRNAs or what have you, and then turn the skin cell into a neuron. And this transdifferentiation protocol actually preserves the epigenetic age, you know. And so we have shown, in collaboration with several groups, that yes, the resulting neuron has the epigenetic age of the skin cell." (said at 0:46:26)
Direct reprogramming (transdifferentiation) of human skin fibroblasts directly into neurons—using factors such as microRNAs—bypasses the pluripotency stage and preserves the donor cell's epigenetic age and aging-associated transcriptomic and cellular hallmarks. When evaluated using DNA methylation-based epigenetic clocks, the epigenetic age of the induced neurons strongly correlates with and matches the epigenetic age of the starting donor fibroblasts.
Cellular reprogramming using Yamanaka factors completely resets the epigenetic clock back to a prenatal stage.
"the number one proof-of-principle study is really the administration of these Yamanaka factors, because it completely resets the age, actually, to a prenatal stage, you know." (said at 0:47:42)
Cellular reprogramming of somatic cells into induced pluripotent stem cells (iPSCs) via Yamanaka factors completely resets epigenetic aging biomarkers. In the landmark study establishing the multi-tissue epigenetic clock (Horvath clock), DNA methylation age in embryonic stem cells and iPSCs derived from somatic cells was demonstrated to be reset to near zero (prenatal/embryonic stage).
Transient or interrupted cellular reprogramming with Yamanaka factors resets epigenetic age by several years while allowing cells to maintain their somatic identity.
"if you do it briefly for, let's say, five days, you get the benefit of rejuvenation. You may have rejuvenated the cell by 5 years or 10 years, you know, but it still remembers its identity, you know. And so... Does the epigenome reset a little bit? Like it only... Yes, yes. So a couple of groups that are working on it and have already shown that effect, you know, yes. So I analyzed fibroblasts and endothelial cells from from such an intervention. It's called sometimes interrupted reprogramming or transient reprogramming, you know. And um and and sure enough, you know, that that idea worked. It reset the age" (said at 0:48:53)
Published experimental studies confirm that transient or interrupted exposure of human somatic cells (such as fibroblasts, endothelial cells, and muscle stem cells) to reprogramming factors resets DNA methylation epigenetic clocks by several years to decades without permanently abolishing somatic cell identity. Because the evidence is derived from in vitro cell culture and preclinical laboratory models, the GRADE certainty is low.
- supports: Transient non-integrative expression of nuclear reprogramming factors promotes multifacete… (Nature communications 2020) · cited 317x in the literature
"Here we show that transient expression of nuclear reprogramming factors, mediated by expression of mRNAs, promotes a rapid and broad amelioration of cellular aging, including resetting of epigenetic clock, reduction of the inflammatory profile in chondrocytes, and restoration of youthful regenerative response to aged, human muscle stem cells, in each case without abolishing cellular identity." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Multi-omic rejuvenation of human cells by maturation phase transient reprogramming. (eLife 2022) · cited 182x in the literature
"The epigenome was rejuvenated to a similar extent, including H3K9me3 levels and the DNA methylation ageing clock. The magnitude of rejuvenation instigated by MPTR appears substantially greater than that achieved in previous transient reprogramming protocols." (abstract, results, passage verified)
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Caloric restriction slows epigenetic aging in mice, while a high-fat diet accelerates epigenetic aging in mice.
"Definitely caloric restriction slows the epigenetic clock in mice, and we know that because several groups have looked at it, including my group. All of us arrive at the same answer. Conversely, by the way, high-fat diet, you know, accelerates the epigenetic age of mice, you know." (said at 0:52:16)
Published mouse studies evaluating DNA methylation-based epigenetic clocks consistently show that caloric restriction slows epigenetic aging, whereas a high-fat diet accelerates epigenetic aging. Animal studies by multiple groups developing and validating mouse epigenetic clocks have confirmed that caloric restriction significantly decreases epigenetic age acceleration, while high-fat feeding augments age-related DNA methylation changes and epigenetic age.
In a randomized clinical trial of 51 vitamin D-deficient African Americans, supplementation with 4,000 IU/day of vitamin D reduced Horvath epigenetic age by approximately 1.8 years.
"a pretty recent randomized controlled clinical trial with vitamin D supplementation in a population that started off unhealthy. So these were obese African Americans, which were very low in vitamin D. Um African Americans tend to be the lowest in vitamin D because they have a natural sunscreen. And so they were given 4,000 IU of vitamin D a day, and after—I can't remember how long the trial was—a certain period of time, their epigenetic clocks were measured at baseline and after, and the epigenetic clock, Horvath—the Horvath clock was was used. Um it's it basically was reduced by 1.8 years or something like that. And you mentioned the significance is a little—the sample size is small, and so it's kind of like— I mean, it's an exciting finding. I think it was based on 51 people, and it's it's a nice finding." (said at 0:57:18)
The statement accurately summarizes the findings of a 16-week randomized controlled trial in 51 overweight or obese African Americans with vitamin D deficiency/insufficiency (serum 25(OH)D < 50 nmol/L). In the study, participants receiving 4,000 IU/day of vitamin D3 demonstrated an average 1.85-year reduction in Horvath epigenetic aging compared with placebo (p = 0.046). The evidence certainty is rated moderate due to the small sample size across intervention arms and the need for replication in larger trials.
In an observational analysis from the Women's Health Initiative cohort, fish oil/omega-3 supplementation was associated with slower epigenetic aging according to the GrimAge clock.
"Interestingly, according to GrimAge, we did find that people who used omega-3 supplements or fish oil, they were actually aging more slowly. ... we analyzed really an observational study, and that's our problem: our study was an epidemiological study, I want to say the Women's Health Initiative. And and there we did see this association that women who took fish oil supplements were aging more slowly according to GrimAge, you know." (said at 0:59:23)
In the landmark study introducing the DNAm GrimAge epigenetic clock (Lu et al., 2019), the investigators analyzed large cohort datasets including the Women's Health Initiative (WHI) and the Framingham Heart Study to evaluate cross-sectional associations between lifestyle factors, dietary supplement use, and epigenetic age acceleration. They identified an association between omega-3/fish oil supplementation and negative GrimAge acceleration (slower biological aging relative to chronological age). Subsequent randomized clinical trial data (such as the DO-HEALTH trial) and Mendelian randomization studies have similarly observed that omega-3 intake or supplementation is associated with deceleration across second-generation DNA methylation clocks, including GrimAge.
- supports: DNA methylation GrimAge strongly predicts lifespan and healthspan. (Aging 2019) · cited 2723x in the literature
"These DNAm-based biomarkers show the expected relationship with lifestyle factors including healthy diet and educational attainment. Overall, these epigenetic biomarkers are expected to find many applications including human anti-aging studies." (abstract, conclusions)
pubmedfull study (doi) - supports: Individual and additive effects of vitamin D, omega-3 and exercise on DNA methylation cloc… (Nature aging 2025) · cited 126x in the literature
"In summary, our trial indicates a small protective effect of omega-3 treatment on slowing biological aging over 3 years across several clocks, with an additive protective effect of omega-3, vitamin D and exercise based on PhenoAge." (abstract, conclusions, passage verified)
pubmedfull study (doi) - supports: Causal impact of genetically-determined fish and fish oil intake on epigenetic age acceler… (Human genomics 2025) · cited 2x in the literature
"We report that oily fish consumption appears to decrease PhenoAge acceleration (p < 0.0086), whereas fish oil supplementation appears to decrease GrimAge (p = 0.037). Both omega-3 exposures modify the epigenetic clocks in the expected negative, or age-decelerating, direction." (abstract, results, passage verified)
pubmedfull study (doi)
Differentiating an induced pluripotent stem cell (iPSC) into a mature cell, such as a neuron, only increases its epigenetic age by roughly one to two years.
"if you take, for example, a stem cell, an iPS cell, and then differentiate it into a more mature cell, for example a more mature neuron, you will find that the epigenetic age increases. The issue is it doesn't increase by a lot, you know. So a more differentiated cellular more mature cell maybe maybe one or two years older than the stem cell." (said at 0:46:01)
The claim that differentiating induced pluripotent stem cells (iPSCs) into derived cells, such as neurons, results in only a minimal increase in epigenetic age is supported by published evidence. Epigenetic clock analyses show that reprogramming somatic cells resets their DNA methylation age to a baseline fetal/embryonic age (near zero). While subsequent differentiation into neurons causes a slight increase in epigenetic age, the resulting cells remain at an embryonic or fetal stage (roughly zero to a couple of years of developmental age) rather than regaining adult epigenetic maturity.
The p16INK4a gene is methylated during early life and undergoes progressive demethylation as an individual ages.
"one particular gene that is methylated during early early age, but then becomes demethylated as, you know, a person ages, is this p16INK4a gene. And it plays a role in cell cycle progression, um meaning it like, you know, it it basically stops the cell from from going on to the next cycle." (said at 0:39:56)
The speaker accurately describes the epigenetic derepression of the p16INK4a (CDKN2A) locus during aging and cellular senescence. In young proliferating cells, the p16INK4a locus is epigenetically silenced through repressive histone methylation marks (specifically trimethylation of histone H3 lysine 27, H3K27me3) deposited and maintained by Polycomb group (PcG) protein complexes. As cells and organisms age, PcG expression and binding decrease, while H3K27 demethylases such as JMJD3 (KDM6B) are upregulated, removing these repressive methyl groups and leading to the transcriptional activation of p16INK4a, which halts cell cycle progression and induces senescence.
- supports: Polycomb mediated epigenetic silencing and replication timing at the INK4a/ARF locus durin… (PloS one 2009) · cited 134x in the literature
"Here we show that in young proliferating embryonic fibroblasts (MEFs) the Polycomb Repressive Complex 2 (PRC2) member EZH2 together with PRC1 members BMI1 and M33 are strongly expressed and localized at the INK4/ARF regulatory domain (RD) identified as a DNA replication origin. When cells enter senescence the binding to RD of both PRC1 and PRC2 complexes is lost leading to a decreased level of histone H3K27 trimethylation (H3K27me3). This loss is accompanied with an increased expression of the histone demethylase Jmjd3 and with the recruitment of the MLL1 protein, and correlates with the expression of the Ink4a/Arf genes." (abstract, passage verified)
pubmedfull study (doi) - supports: Histone deacetylase controls adult stem cell aging by balancing the expression of polycomb… (Cellular and molecular life sciences : CMLS 2010) · cited 129x in the literature
"Decreased expression of histone deacetylases (HDACs), followed by downregulation of polycomb group genes (PcGs), such as BMI1, EZH2 and SUZ12, and by upregulation of jumonji domain containing 3 (JMJD3), was observed in senescent MSCs." (abstract, passage verified)
pubmedfull study (doi) - supports: Histone demethylase Jumonji D3 (JMJD3/KDM6B) at the nexus of epigenetic regulation of infl… (Journal of molecular medicine (Berlin, Germany) 2014) · cited 151x in the literature
"JMJD3 potentiates gene expression by demethylating repressive H3K27me3 epigenetic marks in promoters and gene bodies... Conversely, JMJD3 displaces polycomb complexes from the INK4 box, which induces the expression of INK4a and triggers cellular senescence." (abstract)
pubmedfull study (doi)
In the Women's Health Initiative, women with sleep disturbances had slightly accelerated epigenetic age in blood.
"We looked at um people who are—women who have sleep disturbances in the Women's Health Initiative, and sure enough, um they their age, epigenetic age of blood was slightly accelerated." (said at 1:02:35)
A 2017 cross-sectional analysis of 2,078 postmenopausal women from the Women's Health Initiative (WHI) found that self-reported insomnia symptoms (such as restlessness, trouble falling or staying asleep, and early waking) were significantly associated with advanced epigenetic age in blood (β = 1.02, p = 0.005) after adjusting for demographic and health covariates.
The blood epigenetic age of centenarians and supercentenarians is measured to be substantially younger than their chronological age, potentially up to 15 years younger.
"if you analyze the blood for from a centenarian or supercentenarian, it's true, our age estimates are really way below their chronological ages, could be 15 years younger, you know. So there's a real leveling-off effect, you know." (said at 1:04:18)
Studies measuring DNA methylation age in blood samples from centenarians and semi-supercentenarians (individuals aged 105–109) demonstrate that their epigenetic age is substantially younger than their chronological age. A study examining peripheral blood mononuclear cells (PBMCs) from 82 Italian semi-supercentenarians (mean chronological age: 105.6 years) found that their epigenetic age was on average 8.6 years younger than expected based on chronological age (with individual variation reaching up to ~15 years), and their offspring were also epigenetically younger (5.1 years younger) than age-matched controls.
- supports: Decreased epigenetic age of PBMCs from Italian semi-supercentenarians and their offspring. (Aging 2015) · cited 338x in the literature
"We analyze the DNA methylation levels of peripheral blood mononuclear cells (PBMCs) from Italian families constituted of 82 semi-supercentenarians (mean age: 105.6 ± 1.6 years), 63 semi-supercentenarians' offspring (mean age: 71.8 ± 7.8 years), and 47 age-matched controls (mean age: 69.8 ± 7.2 years). We demonstrate that the offspring of semi-supercentenarians have a lower epigenetic age than age-matched controls (age difference=5.1 years, p=0.00043) and that centenarians are younger (8.6 years) than expected based on their chronological age." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Aging, exceptional longevity and comparisons of the Hannum and Horvath epigenetic clocks. (Epigenomics 2017) · cited 85x in the literature
"In the long-lived cohort (Sydney Centenarian Study; 95+, n = 23), DNAmage was lower than chronological age for both clocks." (abstract, results, passage verified)
pubmedfull study (doi)
Growth hormone receptor knockout mice age more slowly according to mouse epigenetic clocks.
"these growth hormone knockout mice that are known to live longer, sure enough, according to the epigenetic clocks in mice, they really age more slowly." (said at 1:05:09)
Studies developing and evaluating multi-tissue DNA methylation epigenetic clocks in mice have shown that long-lived dwarf mice, including growth hormone receptor knockout (GHRKO) mice, exhibit a slower rate of epigenetic aging compared to wild-type controls.
Radiation-induced cellular senescence does not accelerate epigenetic clocks.
"Then there are other forms, so-called radiation-induced senescence: you irradiate the cell, and that form of senescence doesn't seem to accelerate the epigenetic clocks, you know." (said at 1:06:44)
Published experimental work directly supports the claim. In in vitro studies evaluating DNA methylation age across different forms of cellular senescence, replicative senescence and oncogene-induced senescence were accompanied by accelerated epigenetic aging, whereas DNA damage- and radiation-induced senescence did not accelerate the Horvath epigenetic clock.
- supports: Epigenetic clock analyses of cellular senescence and ageing. (Oncotarget 2016) · cited 152x in the literature
"Using primary cells, telomerase-expressing cells and oncogene-expressing cells of the same genetic background, we show that induction of replicative senescence (RS) and oncogene-induced senescence (OIS) are accompanied by ageing of the cell. However, senescence induced by DNA damage is not, even though RS and OIS activate the cellular DNA damage response pathway, highlighting the independence of senescence from cellular ageing." (abstract, results, passage verified)
pubmedfull study (doi)
Immortalizing a cell by overexpressing TERT (telomerase reverse transcriptase) does not stop epigenetic aging, and its epigenetic age continues to increase with passaging.
"conversely, there are ways of immortalizing cells by overexpressing the component of the telomerase, the TERT. Now that—so immortalizing a cell actually doesn't stop epigenetic aging, you know. You can have an immortalized cell that you can passage for decades, but the epigenetic age keeps going up." (said at 1:06:58)
In vitro experimental studies tracking DNA methylation across extended cellular passaging demonstrate that ectopic expression of telomerase reverse transcriptase (hTERT) immortalizes human somatic cells and bypasses replicative senescence, but does not halt the progression of epigenetic aging. Epigenetic clocks (such as the Horvath DNA methylation clock) show that hTERT-immortalized cells continue to accumulate age-associated DNA methylation changes and increase in epigenetic age as they undergo successive cell divisions.
- supports: Epigenetic clock analyses of cellular senescence and ageing. (Oncotarget 2016) · cited 152x in the literature
"Consistent with this, we observed that telomerase-immortalised cells aged in culture without having been treated with any senescence inducers or DNA-damaging agents, re-affirming the independence of the process of ageing from telomeres and senescence." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Epigenetic ageing is distinct from senescence-mediated ageing and is not prevented by telo… (Aging 2018) · cited 81x in the literature
"Although hTERT did not induce any perceptible change to the rate of epigenetic ageing, hTERT-expressing cells, which bypassed senescence, continued to age epigenetically... Hence, while re-activation of hTERT may stave off physical manifestation of ageing through avoidance of replicative senescence, it would have little impact on epigenetic ageing which continues in spite of telomerase activity." (abstract, results and conclusions)
pubmedfull study (doi) - supports: Epigenetic clock analysis of human fibroblasts in vitro : effects of hypoxia, donor age, a… (Aging 2019) · cited 25x in the literature
"hTERT expression did not arrest cell division-associated progression of DNAm age in most cells." (abstract, results, passage verified)
pubmedfull study (doi)
Steve Horvath's original epigenetic clock used 353 genomic loci, while the GrimAge clock developed by Ake Lu uses over 1,000 locations in the genome.
"my original clock used 353 loci. When we look at GrimAge from Ake Lu, a scientist in my lab, it uses over 1,000 locations in the genome." (said at 1:08:08)
Steve Horvath's original pan-tissue epigenetic clock, published in 2013, was constructed using 353 CpG loci to estimate DNA methylation age. The subsequent mortality-risk epigenetic clock, DNAm GrimAge, developed by Ake T. Lu and colleagues in Horvath's laboratory, incorporates DNA methylation-based surrogate markers for plasma proteins and smoking history that encompass 1,030 unique CpG locations in the genome.
DNA methylation sites that gain methylation with aging are enriched in Polycomb group protein target sites.
"sites that gain methylation with aging um are known to be located in so-called Polycomb group protein target sites, so certain proteins that play a very important role in maintaining stem cells, you know." (said at 1:09:32)
Published genomic analyses across human tissues and diverse mammalian species consistently demonstrate that CpG sites that undergo age-associated hypermethylation are substantially enriched at Polycomb group target genes (such as Polycomb Repressive Complex 2 / PRC2 binding sites), which play a central role in maintaining stem cell pluripotency and regulating developmental gene expression.
- supports: Age-dependent DNA methylation of genes that are suppressed in stem cells is a hallmark of … (Genome research 2010) · cited 896x in the literature
"We demonstrate that stem cell PCGTs are far more likely to become methylated with age than non-targets (odds ratio = 5.3 [3.8-7.4], P < 10(-10)), independently of sex, tissue type, disease state, and methylation platform." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Universal DNA methylation age across mammalian tissues. (Nature aging 2023) · cited 410x in the literature
"We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity." (abstract, results, passage verified)
pubmedfull study (doi)
DNA methylation sites that lose methylation with aging are enriched in enhancer regions.
"The sites that lose methylation um also are enriched with certain themes, for example, often they're in so-called enhancer regions, you know." (said at 1:09:53)
Epigenome-wide association studies across human tissues and mammalian model organisms consistently demonstrate that DNA methylation sites undergoing age-associated hypomethylation (loss of methylation) are significantly enriched within non-CpG island regulatory domains, particularly enhancer and super-enhancer regions, whereas age-associated hypermethylation predominantly clusters at promoter CpG islands and Polycomb-repressed chromatin regions.
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.