Introduction
Everyone has a chronological age. That is simply the number of years since birth.
Researchers are also trying to measure something more complicated: biological ageing. This means the gradual changes inside cells, tissues, and organs that make one person’s body function differently from another person’s body at the same chronological age.
One of the most studied ways to estimate biological ageing looks at tiny chemical tags attached to DNA.
These tags are called methyl groups.
They do not change the DNA code. Instead, they are part of a regulatory system that influences how DNA is used.
A simple analogy is:
DNA is the instruction book. Methyl tags are small regulatory notes attached to different pages.
As people age, some of these methyl-tag patterns change in predictable ways.
Scientists noticed that they could measure many of these DNA changes at once and use mathematics to create age-related estimates.
These mathematical tools became known as epigenetic clocks. (Research)
The most important question, however, is not simply whether a clock can estimate age.
It is:
If a treatment makes an epigenetic clock look younger, has the person actually become biologically younger?
That question is much harder to answer.
Human studies now show that calorie restriction, omega-3 fatty acids, multivitamin-mineral supplements, some dietary programs, and several prescription medicines can move certain epigenetic clocks.
But the changes are usually small.
Different clocks frequently disagree.
And a younger clock result has not yet been proven to mean that a person’s organs became younger, their disease risk fell, or their lifespan increased. (Review, Review)
This article therefore follows five simple questions:
Level 1: Can DNA methylation estimate chronological age?
Level 2: Can it estimate health-related ageing?
Level 3: Can it estimate how fast ageing is happening?
Level 4: Can treatments change these measurements?
Level 5: Does changing the measurement prove genuine rejuvenation?
The evidence becomes less certain as we move from Level 1 toward Level 5.
Informational only; no medical, dosing, or emergency instructions.
Quick Summary
- Epigenetic clocks use patterns of chemical tags on DNA to calculate age-related estimates. (Research)
- The earliest clocks were built mainly to estimate chronological age. (Research)
- Newer clocks were designed to capture information related to health, disease risk, or mortality rather than calendar age alone. (Research, Research)
- Another type of clock estimates how quickly ageing is occurring rather than assigning an age in years. (Research)
- Different clocks can give different answers from the same blood sample because they were built to measure different things. (Research)
- Some clock readings change measurably during a single day, partly because the mixture of blood cells changes. (Research)
- A two-year calorie-restriction trial modestly slowed a pace-of-ageing measure but did not significantly reverse two other biological-age clocks. (Research)
- Large randomized studies of omega-3 fatty acids and multivitamins have produced small favourable changes in selected clocks rather than dramatic age reversal. (Research, Research)
- Smaller studies sometimes report larger clock changes, but these studies often combine several interventions or lack a placebo group. (Research, Research)
- A younger epigenetic-clock result is currently best understood as a biomarker change—not proof that human ageing itself has been reversed. (Review)
What It Is (Clinical Definition & Classification)
An epigenetic clock is a mathematical model that reads patterns of DNA methylation and turns them into an age-related measurement.
Why focus on DNA methylation?
This is the key point.
Ageing affects many biological systems.
Researchers could examine:
- proteins
- metabolism
- immune function
- organ function
- gene activity
- DNA regulation
DNA methylation became especially useful because some methylation changes occur in predictable age-related patterns.
That means researchers can collect a blood, saliva, or tissue sample, measure many methylation sites, and compare the pattern with patterns seen in other people.
The result is not a direct measurement of “how old every cell is.”
It is a statistical estimate.
What is a CpG site?
Many clock studies refer to CpG sites.
A CpG site is simply one specific type of location in DNA.
Scientists measure whether a methyl tag is present at many of these locations.
A reader does not need to memorize the chemistry.
The important idea is:
An epigenetic clock looks at many specific DNA locations and asks whether their pattern looks younger, older, healthier, or faster-ageing compared with reference data.
The clocks can then be divided into five levels.
Level 1 — Can DNA Estimate Chronological Age?
Yes.
This is the most established part of the field.
The Horvath clock, published in 2013, used methylation patterns from many tissues to estimate chronological age. (Research)
Another early clock, developed by Hannum and colleagues, used blood methylation patterns. (Research)
These clocks essentially ask:
“How old does this DNA pattern look?”
They can estimate chronological age surprisingly well.
But predicting calendar age is not the same as measuring health.
That led researchers to build a second type of clock.
Level 2 — Can DNA Estimate Health-Related Ageing?
Researchers began building clocks designed to reflect health and mortality risk.
One is called PhenoAge.
The name comes from “phenotypic age,” meaning age estimated partly from measurable characteristics of the body rather than calendar age alone.
PhenoAge was designed to capture information related to ageing-associated health and mortality. (Research)
Another is called GrimAge.
The name is dramatic, but the idea is straightforward.
GrimAge uses DNA methylation to estimate biological information related to smoking exposure and several circulating proteins. It was developed to improve prediction of mortality-related outcomes. (Research)
These clocks ask a somewhat different question:
“Does this DNA pattern resemble patterns seen in people with healthier or less healthy ageing?”
That still does not make them direct measurements of health.
They are statistical risk markers.
Level 3 — Can DNA Estimate How Fast Ageing Is Happening?
A newer approach is called DunedinPACE.
The name comes from a long-running study in Dunedin, New Zealand.
PACE stands for Pace of Aging Computed from the Epigenome.
Instead of asking how old someone appears, it attempts to estimate how quickly age-related physiological change is happening. (Research)
The easiest analogy is:
An age clock is somewhat like an odometer. DunedinPACE is more like a speedometer.
The odometer asks how much distance has accumulated.
The speedometer asks how fast the car is moving now.
This distinction becomes extremely important when people talk about “age reversal.”
Slowing the speed does not erase the distance already travelled.
Level 4 — Can Treatments Change the Clock?
Yes.
This is now supported by randomized human studies.
But different clocks respond differently.
A treatment may improve one clock and leave another unchanged.
A large 2026 review of human intervention studies found positive, neutral, and sometimes unfavourable changes depending on the clock and intervention. (Review)
So:
Epigenetic clocks can respond to treatment, but they do not behave like one universal biological-age meter.
Level 5 — Does Changing the Clock Mean Real Rejuvenation?
This remains unproven.
To show meaningful biological rejuvenation, researchers would ideally connect a younger clock result with outcomes such as:
- better physical function
- better cognition
- improved organ function
- fewer age-related diseases
- less disability
- longer healthy survival
A biomarker that reliably predicts such outcomes after treatment can sometimes become a surrogate endpoint.
A surrogate endpoint is a measurement that can stand in for a clinical outcome because evidence has shown that changing the measurement predicts changing the real-world outcome.
Epigenetic clocks have not yet reached that level of universal validation for ageing interventions. (Review)
Why It Happens (Causes & Risk Factors)
DNA methylation changes throughout life.
Age is one influence, but it is not the only one.
Methylation patterns can also vary with:
- smoking
- inflammation
- metabolism
- disease
- environmental exposures
- different types of blood cells
- tissue type
This explains part of the variation between clock results.
Blood is not one single type of tissue
Blood contains many kinds of immune cells.
Each cell type has somewhat different methylation patterns.
The proportions of these cells can change during the day.
A repeated-sampling study found measurable 24-hour changes in 13 of 17 epigenetic clocks, partly associated with changes in blood-cell composition. (Research)
That means:
A person’s clock can move slightly without their body literally ageing or rejuvenating during those few hours.
Measurement noise also matters
Researchers distinguish between two ideas.
Technical reliability means the laboratory can repeatedly test the same sample and get similar numbers.
Biological stability means separate samples from the same person stay reasonably similar over a short period.
A 2026 study found that many clocks were technically reproducible but some were less stable when new biological samples were collected over short periods. (Research)
This matters because many intervention effects are small.
Mechanisms / Pathophysiology
Methylation is not automatically good or bad
DNA methylation does not simply rise with age.
Some DNA locations gain methyl tags.
Others lose them.
So it would be incorrect to say:
“Ageing happens because DNA becomes too methylated.”
The relevant information is the pattern.
How scientists build a clock
Researchers collect DNA methylation data from many people.
They then use computer models to identify combinations of DNA sites that best predict whatever they want the clock to measure.
For early clocks, the target was largely chronological age. (Research)
For PhenoAge, the target included ageing-related health information. (Research)
For GrimAge, the model was designed around information strongly related to mortality risk. (Research)
For DunedinPACE, the target was how quickly multiple body systems had changed over time. (Research)
Why different clocks disagree
Imagine four instruments:
- a thermometer
- a blood-pressure cuff
- a heart-rate monitor
- a scale
All measure something about the body.
They should not produce the same number.
Epigenetic clocks work similarly.
They all relate to ageing, but they were built to measure different aspects of it.
A 2026 analysis found substantial disagreement among established clocks applied to the same samples. (Research)
Therefore:
There is no single universal epigenetic-age number.
What is “age acceleration”?
Researchers often calculate whether a clock looks older or younger than expected for someone’s chronological age.
If it looks older, this is often called age acceleration.
If it looks younger, researchers may call it age deceleration.
These terms sound stronger than they are.
They describe a statistical result.
They are not diagnoses.
Slowing versus reversing
This is one of the most important concepts in the article.
A major two-year study called CALERIE tested calorie restriction in healthy adults without obesity.
CALERIE stands for a long-term study of reducing calorie intake.
Researchers found that calorie restriction modestly slowed DunedinPACE—the speedometer-like measure of ageing.
But two other clocks, PhenoAge and GrimAge, did not show significant age reversal. (Research)
So the accurate conclusion is:
Calorie restriction modestly slowed one measure of ageing speed.
Not:
Calorie restriction made people biologically younger.
Symptoms, Patterns, and Differential Clues
Epigenetic age does not have a recognizable symptom pattern.
Fatigue does not diagnose an accelerated epigenetic clock.
Wrinkles do not diagnose it.
Memory problems do not diagnose it.
And feeling healthy does not guarantee a younger clock result.
Clock measurements can differ because of:
- the clock chosen
- the tissue tested
- blood-cell composition
- time of sampling
- laboratory variation
- short-term biological changes
- underlying health conditions
A person’s result should therefore not be thought of as one definitive “true biological age.”
Evaluation & Diagnosis (Clinical Context)
Epigenetic clocks are primarily research biomarkers.
A biomarker is something measurable that provides information about biology.
Examples include blood pressure, cholesterol, blood sugar, and DNA methylation.
A clinical outcome is something meaningful that happens to a person, such as:
- developing a disease
- losing physical function
- having a fracture
- developing dementia
- dying
A clock sits much closer to the biomarker side of this spectrum.
Researchers still need to establish when and whether treatment-induced clock changes reliably predict clinical outcomes. (Review)
This is why very small before-and-after changes should be interpreted cautiously.
Treatment Options Snapshot (Evidence-Graded, Descriptive Only)
No treatment is established specifically for the clinical purpose of reversing an epigenetic clock.
The interventions below are research examples.
Prescription / Medical Therapies
- Semaglutide — Researchers performed an additional analysis of a randomized trial in adults living with HIV who had abnormal fat distribution. Several DNA-based ageing measurements moved in a younger or slower-ageing direction, but epigenetic ageing was not the original primary purpose of the trial and the population was highly specific. Evidence: Emerging. (Research)
- Metformin in older adults living with HIV — A randomized study called METFORAGING tested metformin for 96 weeks and measured PhenoAge acceleration, meaning whether a health-related DNA clock looked older or younger than expected. The primary between-group clock result was not significantly improved, providing an important controlled negative finding. Evidence: Limited-Mixed. (Research)
- Metformin in older adults with glucose intolerance — A separate two-year randomized study measured statistically stabilized versions of two older DNA-age clocks and also measured frailty. Selected epigenetic-age measures moved in a favourable direction, but the relationship with physical frailty depended on how frailty was measured. Evidence: Limited-Mixed. (Research)
- Pitavastatin — A cholesterol-lowering drug was studied in a randomized trial population living with HIV. Researchers measured a health-risk clock and a pace-of-ageing clock, but the population and cardiovascular-prevention context make generalization to healthy ageing uncertain. Evidence: Emerging. (Research)
- Growth hormone, DHEA, and metformin combination — A small study called TRIIM gave participants all three interventions and reported younger estimates on several DNA-methylation clocks. There was no placebo group, and the study cannot determine which component caused the clock changes. Evidence: Emerging. (Research)
- Dasatinib plus quercetin-based senolytic treatment — A human study measured several DNA-based ageing clocks during experimental treatment intended to target senescent cells. Some clocks did not improve and some older clock measures moved in an unfavourable direction, showing that senolytic treatment does not automatically make epigenetic age younger. Evidence: Emerging. (Research)
Supplements / Vitamins (Research Context Only)
More than 30 frequently discussed supplements were screened before inclusion.
Available direct human supplement evidence was more limited than the evidence available for standard medical treatment categories in this condition.
Tier A — Strong / Moderate Evidence
- Omega-3 fatty acids — A three-year randomized study called DO-HEALTH followed older adults and measured several DNA-based ageing markers, including a health-related clock and a pace-of-ageing measure. Selected epigenetic-age measures moved modestly in a favourable direction, but the effect was small and does not demonstrate whole-body rejuvenation. Evidence: Moderate. (Research)
- Multivitamin-multimineral supplementation — A large study within the COSMOS randomized trial followed 958 older adults and measured five DNA-based ageing measures. Two statistically stabilized health-related clocks changed slightly more slowly with multivitamin-mineral supplementation, but the size of the effect was modest and its clinical meaning remains uncertain. Evidence: Moderate. (Research)
Tier B — Limited-Mixed Evidence
- Vitamin D — Vitamin D was tested in the same DO-HEALTH trial. Multiple DNA-based ageing measures were evaluated, but vitamin D alone did not show the same consistent pattern as omega-3; an additional signal appeared when vitamin D, omega-3, and exercise were combined. Evidence: Limited-Mixed. (Research)
- Cocoa flavanol extract — Cocoa extract was tested in the COSMOS trial using five epigenetic ageing measures. The clocks did not significantly improve, making this useful randomized evidence against a strong clock-reversal effect from the tested formulation. Evidence: Limited-Mixed. (Research)
Tier C — Emerging Evidence
- Nicotinamide riboside — A small randomized study in older adults with mild cognitive impairment measured two health-related DNA-age clocks and overall DNA methylation. Some exploratory clock results moved favourably, but cognition did not improve and the sample was small. Evidence: Emerging. (Research)
- Folic acid plus vitamin B12 — Human intervention data were reanalyzed using an epigenetic-age clock. DNA-methylation age appeared younger only in a genetically defined subgroup of women, so the finding cannot be generalized to everyone. Evidence: Emerging. (Research)
- Flavanols — A very small human study evaluated compounds from the flavanol family and measured DNA-methylation age. Findings came from only 13 participants and varied by biological context, leaving the broader significance uncertain. Evidence: Emerging. (Research)
- Fisetin — An uncontrolled pilot in ten adults over 50 measured a commercial DNA-based biological-age estimate and telomere length. Four participants moved younger, five moved older, and one did not change; telomere length also did not significantly change. Evidence: Emerging. (Research)
- Delayed-release calcium-AKG plus vitamins — A retrospective study of 42 users reported a reduction in saliva DNA-methylation age. The study lacked randomization and placebo control, used several ingredients together, and relied on a proprietary clock, so it does not establish that AKG alone reverses ageing. Evidence: Emerging. (Research)
- Delayed-release calcium-AKG plus vitamins in a larger observational cohort — A later observational study compared supplement users using a saliva methylation-age score. Users had younger average values, but self-selection and healthier lifestyle patterns could explain part of the difference. Evidence: Emerging. (Research)
- Coenzyme Q10 — The same observational study examined CoQ10 users using a DNA-methylation age score. Adjusted longitudinal analyses were not statistically significant, so current human evidence does not establish clock reversal. Evidence: Emerging. (Research)
Frequently discussed candidates that did not meet the direct human clock-evidence threshold included NMN, regular AKG alone, quercetin alone, resveratrol, spermidine, sodium butyrate, GlyNAC, NAC alone, glycine alone, taurine, urolithin A, curcumin, berberine, sulforaphane, EGCG, alpha-lipoic acid, vitamin C, vitamin E, magnesium, zinc, selenium, melatonin, beta-hydroxybutyrate, astaxanthin, creatine, probiotics, and prebiotics.
This does not mean these compounds have no human research.
It means their human studies did not provide sufficiently direct evidence that the isolated intervention moved a validated epigenetic-age clock.
Topical / Cosmetic Ingredients (Research Context Only)
Available direct human topical/local evidence was limited for this condition.
- Dihydromyricetin-containing topical formulation — A 2026 human skin study created a local epidermal ageing clock and measured skin DNA-methylation age, wrinkles, roughness, and deeper skin imaging measurements after use of a topical formulation. The local clock became younger, but this was one formulation study and cannot establish that the ingredient reverses whole-body ageing. Evidence: Emerging. (Research)
Topical rapamycin was also screened because human studies have reported changes in skin senescence and collagen. Those studies did not directly measure a DNA-methylation ageing clock, so they were not classified as epigenetic-clock reversal evidence.
Dietary Sources (Research Context Only)
Direct human dietary-source evidence was narrower than the target item count.
- Calorie restriction — A two-year randomized study called CALERIE followed healthy adults without obesity and measured a pace-of-ageing clock plus two health-related ageing clocks. The pace-of-ageing measure slowed slightly, but the other two clocks did not show significant reversal. Evidence: Moderate. (Research)
- Mediterranean-style diet — A one-year European study called NU-AGE followed older adults and measured DNA-methylation age. Favourable effects appeared only in selected subgroups rather than consistently across everyone studied. Evidence: Emerging. (Research)
- Plant-rich Mediterranean-style diet with extra polyphenols — A study called DIRECT PLUS compared Mediterranean-style dietary patterns in adults with abdominal obesity or abnormal blood fats. Several different epigenetic clocks changed differently depending on the dietary pattern and clock used, so the results do not establish universal biological-age reversal. Evidence: Limited-Mixed. (Research)
- Vegan diet — An eight-week randomized study used identical twins so that genetics were closely matched between comparison groups. Several DNA-based ageing measures moved in a favourable direction in the vegan group, but calorie intake and weight also changed, making it difficult to know whether the result came from the diet type itself. Evidence: Emerging. (Research)
- Plant-rich diet combined with lifestyle changes — A small randomized study in 43 men combined dietary changes with exercise, sleep, relaxation, probiotics, and other components. A DNA-methylation age estimate became younger relative to controls, but the study cannot determine which part of the program caused the change. Evidence: Emerging. (Research)
- Tree nuts plus extra-virgin olive oil — A short four-week study in adults with metabolic syndrome measured a pace-of-ageing clock and a GrimAge-related measurement. Neither changed significantly during the short study. Evidence: Emerging. (Research)
What Research Has Studied
- Whether DNA methylation can estimate chronological age. (Research)
- Whether newer clocks predict health and mortality better than calendar-age clocks. (Research, Research)
- Whether DNA methylation can estimate how quickly ageing is occurring. (Research)
- How stable clock results are when blood is collected repeatedly. (Research)
- How much different clocks disagree when used on the same person. (Research)
- Whether calorie restriction changes ageing speed. (Research)
- Whether omega-3 fatty acids, vitamin D, and multivitamins change clock measurements. (Research, Research)
- Whether prescription medicines can change selected clocks. (Research, Research)
- Whether senolytic interventions make methylation clocks younger. (Research)
- Whether clock changes across many intervention studies point in a consistent direction. So far, they do not. (Review)
Safety, Interactions & Regulatory Context
Taking a blood or saliva sample for an epigenetic clock is generally much less medically consequential than taking a drug.
The larger issue is interpretation.
A younger result can create false reassurance
A younger clock result does not automatically mean:
- cancer risk is lower
- cardiovascular risk is lower
- cognition improved
- muscles became younger
- organs became younger
- lifespan increased
Those outcomes require their own evidence. (Review)
An older result can create unnecessary alarm
Different clocks can give different age estimates from the same sample. (Research)
Some clock results also change over short periods. (Research)
A surprising result therefore does not necessarily mean rapid biological deterioration.
Treatment safety is a separate question
An intervention should not be considered safe merely because an epigenetic clock moved in a favourable direction.
Drugs, hormones, supplements, and restrictive diets each have their own potential risks.
Clock movement does not cancel those risks.
Evidence Overview
The evidence is easiest to understand by returning to the five levels.
Level 1 — Can DNA methylation estimate chronological age?
Yes.
This is strongly established.
Early clocks such as Horvath and Hannum showed that predictable patterns of DNA methylation can estimate chronological age across people and tissues. (Research, Research)
Level 2 — Can clocks capture health-related ageing?
Yes, to a meaningful degree.
PhenoAge and GrimAge were designed to capture biological information associated with health and mortality rather than merely reproduce calendar age. (Research, Research)
These measurements are useful research predictors.
They are still not complete measures of an individual’s overall health.
Level 3 — Can DNA estimate how fast ageing is happening?
Yes.
DunedinPACE was developed specifically to estimate the speed of ageing-related physiological change. (Research)
This is conceptually different from assigning someone a biological age in years.
Level 4 — Can interventions change clock measurements?
Yes.
This is now supported by randomized trials.
A two-year calorie-restriction trial modestly slowed a pace-of-ageing measure. (Research)
A three-year omega-3 trial produced small favourable changes in selected clocks. (Research)
A large multivitamin trial modestly slowed selected health-related clocks. (Research)
So it is no longer accurate to say epigenetic clocks cannot respond to intervention.
They can.
Level 5 — Does moving the clock prove biological rejuvenation?
No.
This is where the evidence becomes much weaker.
Different clocks often respond differently to the same intervention.
Some move younger.
Some remain unchanged.
Some move in the opposite direction.
A 2026 review of intervention studies found substantial variation across clocks and interventions. (Review)
The most rigorous large trials usually report relatively small effects.
Larger-looking “age reversal” findings tend to come from much smaller studies, multi-component programs, or studies without placebo groups.
For example, a small study called TRIIM reported younger values on several clocks after a combination of growth hormone, DHEA, and metformin. But there was no placebo group, and three active interventions were used together. (Research)
Another small study combined a plant-rich diet with exercise, sleep, relaxation, probiotics, and other lifestyle changes. Its clock estimate became younger relative to controls, but the study cannot determine which component was responsible. (Research)
The scientifically cautious conclusion is therefore:
Human interventions can change epigenetic-age measurements. That is established. Whether those changes represent genuine whole-body rejuvenation remains unproven.
Evidence Confidence Classification
Overall Rating: Limited-Mixed
Confidence is strong that DNA-methylation clocks measure meaningful age-related biological patterns. Confidence is moderate that some interventions can modestly change selected clocks. Evidence remains Limited-Mixed for reproducible reversal across different clocks and is not sufficient to conclude that lowering a clock causes better health or longer life. (Review, Review)
What Does Not (Evidence Gaps)
- One younger clock result as proof of rejuvenation — Different clocks can produce different estimates from the same sample, so a lower number does not prove that every organ or biological system became younger. (Research)
- A slower pace-of-ageing clock as proof that accumulated age was reversed — The CALERIE calorie-restriction trial slowed one pace measure without significantly reversing two other age clocks. (Research)
- Large changes from small studies as stronger evidence than small changes from large trials — Small uncontrolled studies are more vulnerable to bias, random variation, and difficulty identifying which intervention caused the effect. (Research)
- Commercial biological-age testing as one definitive biological age — Different clock algorithms were built for different purposes and can disagree substantially. (Research)
- Epigenetic clocks as fully validated replacements for clinical outcomes — Researchers have not established that treatment-induced clock changes can universally substitute for outcomes such as disability, disease incidence, or mortality. (Review)
- Supplement or drug stacks as proven additive rejuvenation — Multi-component studies cannot determine which component caused a clock change, and controlled human evidence does not establish additive rejuvenation from combining several compounds. (Research)
FAQ
1. What is an epigenetic clock?
An epigenetic clock is a mathematical tool that examines chemical patterns on DNA and calculates an age-related estimate. Most clocks use DNA methylation. (Research)
2. Why is DNA methylation used?
Some DNA-methylation patterns change predictably as people age. Researchers can use those repeated patterns to build mathematical models of ageing.
3. Does methylation change the DNA code?
No.
Methyl groups are chemical tags attached to DNA. They can influence gene regulation but do not rewrite the DNA sequence.
4. What is biological age?
Biological age is a broad idea describing how old the body’s biological systems appear or function compared with chronological age.
There is no single universally accepted test that measures all aspects of biological age.
5. Is epigenetic age the same as biological age?
No.
Epigenetic age is one estimate based on DNA regulation. Biological ageing also involves organs, metabolism, immunity, muscles, brain function, cellular damage, and many other processes.
6. What is the Horvath clock?
The Horvath clock is one of the best-known early DNA-methylation clocks. It was designed to estimate chronological age across many human tissues. (Research)
7. What is PhenoAge?
PhenoAge is a newer clock designed to capture more health-related ageing information than chronological age alone. (Research)
8. What is GrimAge?
GrimAge is a DNA-methylation model designed around biological information related to smoking, circulating proteins, and mortality risk. (Research)
9. What is DunedinPACE?
DunedinPACE estimates how quickly ageing-related physiological change is occurring.
It is easiest to think of it as a speedometer rather than an age in years. (Research)
10. Why can different clocks give different answers?
Because they were designed to measure different things.
Some predict chronological age, some focus more on health risk, and some estimate ageing speed. (Research)
11. Can a clock change during one day?
Some can.
Repeated blood sampling has shown measurable daily variation in many clocks, partly because the mixture of blood-cell types changes. (Research)
12. Has calorie restriction reversed biological age?
A two-year trial modestly slowed a pace-of-ageing measure.
It did not significantly reverse two other health-related clocks, so the evidence is better described as modest slowing rather than age reversal. (Research)
13. Do omega-3 fatty acids make people biologically younger?
A large randomized trial found small favourable changes in selected DNA-age measures.
That demonstrates modest clock modulation, not proven whole-body rejuvenation. (Research)
14. Do multivitamins change epigenetic age?
A large randomized study found modest slowing in two health-related DNA clocks.
The clinical importance of those small changes is not yet known. (Research)
15. Does NMN reverse epigenetic age?
Direct isolated human evidence meeting the clock-specific inclusion criteria for this article was not identified.
Human studies showing changes in NAD-related biology should not automatically be described as epigenetic-age reversal.
16. Does AKG reverse biological age?
Small uncontrolled and observational studies of calcium-AKG formulations combined with vitamins have reported younger methylation-age estimates.
These studies do not establish that AKG alone reverses human ageing. (Research, Research)
17. Does metformin make epigenetic clocks younger?
Human randomized findings are mixed.
One trial did not improve its primary age-clock outcome, while another found favourable changes in selected clocks. (Research, Research)
18. Do senolytics reverse epigenetic age?
Not consistently.
One human study found different responses across different clocks, including unfavourable movement in some measures. (Research)
19. Does a younger epigenetic clock mean someone will live longer?
Not necessarily.
Some clocks predict mortality risk across populations, but researchers have not shown that making a clock younger through treatment automatically makes people live longer. (Review)
20. What is the simplest conclusion?
Epigenetic clocks are useful tools for measuring patterns associated with ageing.
Human interventions can change some of these measurements.
But the strongest current conclusion is:
A younger epigenetic clock means the biomarker changed. It does not yet prove that the person became biologically younger in a clinically meaningful way.
(Review)
Resources
Horvath Multi-Tissue DNA-Methylation Clock — Research — https://pubmed.ncbi.nlm.nih.gov/24138928/
Hannum Blood DNA-Methylation Age Predictor — Research — https://pubmed.ncbi.nlm.nih.gov/23177740/
DNA-Methylation PhenoAge — Research — https://pubmed.ncbi.nlm.nih.gov/29676998/
DNA-Methylation GrimAge — Research — https://pubmed.ncbi.nlm.nih.gov/30669119/
DunedinPACE Measure of the Pace of Aging — Research — https://pubmed.ncbi.nlm.nih.gov/35029144/
Biomarkers and Surrogate Endpoints in Geroscience — Review — https://pubmed.ncbi.nlm.nih.gov/36260264/
Reliability of Epigenetic Clocks — Research — https://pubmed.ncbi.nlm.nih.gov/42525215/
Differences Between Epigenetic Clocks — Research — https://pubmed.ncbi.nlm.nih.gov/42496663/
Daily Variation in Epigenetic Clocks — Research — https://pubmed.ncbi.nlm.nih.gov/38638005/
Human Interventions and Epigenetic Ageing Clocks — Review — https://pubmed.ncbi.nlm.nih.gov/42294499/
CALERIE Calorie Restriction and Epigenetic Ageing — Research — https://pubmed.ncbi.nlm.nih.gov/37118425/
DO-HEALTH Omega-3, Vitamin D, Exercise, and Epigenetic Ageing — Research — https://pubmed.ncbi.nlm.nih.gov/39900648/
COSMOS Multivitamin and Cocoa Epigenetic-Clock Trial — Research — https://pubmed.ncbi.nlm.nih.gov/41803341/
Diet and Lifestyle Program and DNA-Methylation Age — Research — https://pubmed.ncbi.nlm.nih.gov/33844651/
TRIIM Trial — Research — https://pubmed.ncbi.nlm.nih.gov/31496122/
Semaglutide and Epigenetic-Age Measures — Research — https://pubmed.ncbi.nlm.nih.gov/40791720/
METFORAGING Metformin Trial — Research — https://pubmed.ncbi.nlm.nih.gov/42023167/
Metformin, Epigenetic Age, and Frailty — Research — https://pubmed.ncbi.nlm.nih.gov/42620010/
Pitavastatin and Epigenetic Age — Research — https://pubmed.ncbi.nlm.nih.gov/40576558/
Senolytic Treatment and DNA-Methylation Clocks — Research — https://pubmed.ncbi.nlm.nih.gov/38393697/
Nicotinamide Riboside and Epigenetic Ageing Measures — Research — https://pubmed.ncbi.nlm.nih.gov/37994989/
Folate, Vitamin B12, Flavanols, and Epigenetic Age — Research — https://pubmed.ncbi.nlm.nih.gov/30350398/
Fisetin Biological-Age Pilot — Research — https://pubmed.ncbi.nlm.nih.gov/39269340/
Calcium-AKG Formulation and DNA-Methylation Age — Research — https://pubmed.ncbi.nlm.nih.gov/34847066/
Calcium-AKG and Supplement Use in Biological-Age Observational Research — Research — https://pubmed.ncbi.nlm.nih.gov/42166733/
Topical Dihydromyricetin Formulation and Epidermal Methylation Age — Research — https://pubmed.ncbi.nlm.nih.gov/42034839/
Mediterranean Diet and Epigenetic Age — Research — https://pubmed.ncbi.nlm.nih.gov/31981007/
Green-Mediterranean Diet and Epigenetic Ageing — Research — https://pubmed.ncbi.nlm.nih.gov/37743489/
Randomized Vegan Diet and Epigenetic Ageing in Identical Twins — Research — https://pubmed.ncbi.nlm.nih.gov/39069614/
Tree Nuts, Olive Oil, and Epigenetic-Age Measures — Research — https://pubmed.ncbi.nlm.nih.gov/42527728/
Nutrition Interventions and Epigenetic Ageing — Review — https://pubmed.ncbi.nlm.nih.gov/39077104/