Key takeaways
- In the 2018 study that created PhenoAge, a score built from nine routine blood tests predicted disease and death better than the DNA test built to mirror it.
- A “pace of aging” score works like a speedometer, not an odometer, so it may react to a rough week and says nothing about the years already behind you.
- New organ-age blood tests found about 1 in 5 people had one organ aging faster than expected, but they still need testing in many more people before clinics can use them.
- A 2024 paper from an international group of aging scientists said there is no blueprint yet for what to do about an abnormal biological-age result.
- Blood pressure, blood sugar, kidney tests, fitness and walking speed already track aging, and your clinician knows what to do with each of them.
In 2018, a team led by Morgan Levine, then at the University of California, Los Angeles, set out to build a better aging clock1. They worked in two steps.
First, they used blood test results and death records from 9,926 adults in NHANES III, a nationally representative federal health survey. From 42 clinical markers, they kept the nine that, along with calendar age, best predicted death from aging-related diseases such as heart disease, cancer and diabetes1. They called the result “phenotypic age.”
Second, they trained a DNA test to copy that score. It reads 513 spots where small chemical tags, called methyl groups, sit on DNA1. That became DNAm PhenoAge, an epigenetic clock that has since been licensed for commercial use2.
Then came a finding many buyers never hear. In the paper’s own discussion, the authors reported that the plain lab version predicted illness and death better than the DNA version did1. If you want to predict risk, they wrote, clinical measures may be the better choice. DNA measures, they added, have advantages for studying how aging works inside cells and tissues1.
That’s worth knowing if a biological-age report is sitting in your inbox. Our article on biological-age tests showed how much these scores can wobble from one test to the next. This guide covers what comes after: what your numbers mean, what to ask, and what a result should change.
Three kinds of scores answer three different questions
Most reports give one of three kinds of numbers. Find out which one you have.
An age. Many tests report a “biological age” in years, and the headline is the gap from your calendar age. Some clocks were trained to guess calendar age. Others, like PhenoAge, were trained on disease and death1.
A pace. DunedinPACE and similar tests report a speed: how fast biological change is building up right now. The Biomarkers of Aging Consortium, an international group of aging researchers, compares pace measures to a car’s speedometer and age clocks to its odometer2.
A speedometer shows how fast you’re going right now. It says nothing about the miles already on the car. The consortium also warns that pace measures may overreact to short-term upsets2.
An organ profile. The newest tests estimate separate ages for organs such as the heart, brain and kidneys, using proteins in your blood56.
Age scores carry a caution of their own. A higher-than-expected biological age could mean you’re aging fast now, or it could reflect harm from years ago, the consortium notes2. A single reading can’t tell those apart.
Organ-age tests are the newest scores, and the least tested
In December 2023, a Stanford team led by Tony Wyss-Coray reported in Nature that blood proteins could date individual organs5. They measured nearly 5,000 blood proteins in more than 5,600 people. About 900 of those proteins came mainly from one organ, and computer models used them to estimate ages for 11 organs5.
About 20% of people had one organ aging faster than expected, and fewer than 2% had more than one5. An older-looking heart went with more than twice the chance of developing heart failure within 15 years5. Older-looking kidneys were more common in people with high blood pressure or diabetes5.
Below, we look at what “more than double” can mean, using our own arithmetic and a made-up starting point. If 5 in 100 people your age would develop heart failure over 15 years, double would be 10 in 100. The other 90 still wouldn’t.
In July 2025, the team scaled up in Nature Medicine6. They measured 2,916 proteins in 44,498 volunteers from the UK Biobank, a British research study, and followed them for up to 17 years6.
Risk of death climbed with the number of aged organs. The hazard ratio was 2.3 for people with two to four aged organs and 8.3 for those with eight or more6. An unusually old brain carried roughly the Alzheimer’s risk of one copy of APOE4, a gene variant that raises the odds of the disease6. A youthful brain and a youthful immune system each went with lower risk of death6.
These results come from research groups, not your doctor’s office. Wyss-Coray told NIH in 2024 that the technique needs testing in far larger groups before clinics can use it5. The 2025 analysis drew on one British study, and it shows links, not causes6.
So if a report says your heart or kidneys look “older,” treat it as a prompt, not a diagnosis. Ordinary tests of those organs already exist.
Read the fine print before you read the number
In 2024, the Biomarkers of Aging Consortium spelled out in Nature Medicine what’s missing from most aging scores4. Studies report risk in different units, so results often can’t be compared. Most scores were checked mainly against death, not frailty or disability. And the big studies used to test them drew heavily on people of European ancestry4.
This decoder is our own tool. Match each line of your report to a row.
| On your report | What it means | What to ask | What not to do |
|---|---|---|---|
| “Biological age 47” (you’re 52) | An estimate from one clock; others may disagree2 | Which clock, and what was it trained to predict?1 | Count the gap as years gained or lost |
| “Pace of aging 1.08” | A rate of change right now, like a speedometer2 | Were you sick, stressed or short on sleep when sampled?2 | Compare it with another company’s pace score |
| “Heart age: older” | A protein-based risk estimate from research cohorts56 | Has this model been tested outside the group it was built on?45 | Assume your heart is diseased |
| A percentile or “younger than 80% of people” | A rank against a comparison group | Who is in that group, by age, ancestry and country?4 | Assume the ranking fits you if you’re unlike them |
| “35% higher risk” | A relative risk, often per year or per standard deviation4 | Higher than what, per what unit, and what’s my absolute risk?4 | Read a relative number as your own odds |
| A margin of error, or none | How far a repeat run could land | Has the company published repeat-test results? | React to a change smaller than the error |
| A product or “protocol” offered with your results | The tester is also the seller | What human trials show it improves health, not just the score?2 | Buy it on the strength of the score alone |
No expert group says a score should change your treatment
The strongest cautions come from scientists who build and study these tests. In a 2023 review in the journal Cell, consortium members noted that U.S. regulators had not cleared any aging biomarker, of any kind, for use in patient care2. None has been formally validated as a stand-in for real health outcomes, either2.
Their 2024 Nature Medicine paper went further. Whether these scores help patients still has to be shown in forward-looking clinical trials, the authors wrote4.
A third consortium paper, in Nature Aging in 2024, stated that there’s no blueprint for how to respond to an abnormal result3. In the group’s survey of experts, about 40% tracked their own health with these tools, and some who didn’t said individual-level prediction isn’t there yet3.
Several of those authors disclosed business ties to epigenetic testing companies3. Even insiders are saying “not yet.”
| Claim | What the research shows | Rating |
|---|---|---|
| Aging scores predict death and disease across large groups | Each year of phenotypic age above calendar age carried about 9% higher death risk1; organ ages tracked later disease56 | , for groups |
| Organ-age blood tests predict disease in that organ | Large observational studies, mainly one British cohort; more testing needed56 | |
| A DNA clock adds much over routine labs for predicting risk | In PhenoAge’s original study, the lab version predicted better1 | |
| Better heart-health habits go with a younger blood-chemistry age | One preliminary, one-time-snapshot study of about 6,500 adults7 | |
| Lowering your score improves your health | Still has to be shown in clinical trials4 | |
| A score can guide your personal treatment | None approved for clinical use; no blueprint for acting on results23 |
The labs you already have carry much of the same signal
PhenoAge’s nine ingredients are all routine clinical lab tests. They are albumin, creatinine, glucose, C-reactive protein, lymphocyte percent, mean cell volume, red cell distribution width, alkaline phosphatase and white blood cell count1.
In the federal survey data, each one-year rise in phenotypic age, beyond calendar age, went with a 9% higher risk of death1. With a made-up example, by our arithmetic: if 10 in 100 people your age would die over 12 years, 9% higher is about 11 in 100.
Heart-health habits show up in that same score. Columbia University researchers studied more than 6,500 U.S. adults from the 2015–2018 round of the same federal survey and shared the preliminary results at the AHA’s Scientific Sessions in November 20237. They scored each person on Life’s Essential 8, the AHA’s eight-part heart-health checklist.
Measured against calendar age, people with the highest scores came out about six years younger in phenotypic age than people with the lowest scores, after accounting for social, economic and demographic factors7. It was a snapshot, measured once, so it shows a link rather than proof that changing habits changes the score7. We found no full journal paper on it as of October 2026.
Fitness belongs on the list, too. In 2016, an AHA scientific statement led by Robert Ross of Queen’s University urged clinicians to measure cardiorespiratory fitness in routine care89. Low fitness predicted death more strongly than smoking, high blood pressure, high cholesterol or type 2 diabetes, the statement said8.
Five ordinary measures that track aging
This table is our own.
| Measure | Why it counts | Where to get it |
|---|---|---|
| Blood pressure | Better blood pressure scores went with a younger phenotypic age14; high blood pressure went with older-looking kidneys5 | Any clinic, many pharmacies, a home cuff |
| Blood sugar | Glucose is one of PhenoAge’s nine inputs1; diabetes went with older-looking kidneys5 | A routine blood test at a checkup |
| Kidney function | Creatinine, a kidney waste product, is a PhenoAge input1 | A routine blood test at a checkup |
| Cardiorespiratory fitness | Low fitness predicted death more strongly than several classic risk factors89 | A clinician’s estimate or an exercise test |
| Walking speed and grip | Aging researchers list both as physical biomarkers of aging2 | A stopwatch, a hallway and a clinic grip gauge |
Our articles on walking speed and on muscle explain how to check those two.
Many natural-health readers want proof that their choices are working, and that instinct fits the evidence. Many of the measures with solid track records are ones you can see, feel and change: how far you walk, how hard you can work, how your blood pressure responds to a new habit.
The consortium’s own wish list for a good aging marker includes being minimally invasive, reliable and responsive to change2. A home blood pressure cuff and a stopwatch meet much of that list.
What a “younger” or “older” result should change
If your result says “older,” don’t panic. One reading can’t separate fast aging now from old damage2, and no score is approved to guide care2. Don’t start, stop or change any medicine because of it.
If your result says “younger,” enjoy it, but keep your checkups and recommended screenings. No aging score has been validated as a stand-in for real health outcomes2.
Either way, look hard at any product the testing company sells alongside your results. Ask what human trials show it improves health, not just the score2. A companion article in this series sorts popular longevity supplements by their evidence.
When to bring a report to a clinician:
- It flags your heart, kidneys or blood sugar. Ask for the standard tests that check those organs; blood pressure and diabetes both tracked with older-looking kidneys in research5.
- It shows a routine lab value, such as glucose or creatinine, outside the lab’s normal range. These standard tests are among PhenoAge’s inputs, and your clinician knows how to read them1.
Your epigenetic data may outlive the test
Some clocks are already licensed for insurance work. The 2023 Cell review lists PhenoAge and GrimAge, a clock trained on death risk, as licensed for use in life insurance2. In a 2021 article in the Journal of Insurance Regulation, published by the National Association of Insurance Commissioners, two authors argued that saliva-based epigenetic tests could help life insurers classify risk13.
The main federal shield, the Genetic Information Nondiscrimination Act of 2008 (GINA), is the basis for limits on how health insurers use genetic information. It was written around genetic signs of a built-in tendency toward disease, the authors note13. They describe epigenetic data as something different: a reading of current health that can change13.
Florida passed GINA-style limits for life insurers in 2020, they add13. Treat your results as sensitive. Our articles on family health history and on consumer DNA kits explain what GINA leaves out.
Before you test, read the privacy policy. Find out whether your sample and data are kept, sold or used for research, and how to delete them.
An FDA rule for lab-built tests came and went
When a lab makes and runs its own test, it’s called a laboratory-developed test, or LDT11. On May 6, 2024, the FDA finalized a rule to oversee these tests as medical devices10.
Two lab industry groups, the American Clinical Laboratory Association and the Association for Molecular Pathology, sued along with others12. On March 31, 2025, the U.S. District Court for the Eastern District of Texas vacated the rule11. The court found that these tests are professional medical services, not devices the FDA may regulate12.
The FDA didn’t appeal, and on September 19, 2025, it formally removed the rule’s text and returned to its earlier hands-off policy, called enforcement discretion1011.
So ask the company whether its test is an LDT, and what validation it has published. Our article on biological-age tests explains what lab certification does and doesn’t prove.
Questions readers ask
Should I retest to see whether my new habits worked?
You can, but read the change with caution. There’s no accepted method yet for combining repeat results from one person4, and pace scores may react to short-term upsets2. Changes in blood pressure, fitness or walking speed are easier to interpret.
My report says my heart is “older.” Do I have heart disease?
Not necessarily. Organ-age scores are risk estimates from blood proteins, and they still need testing in many more people5. Share the report with your clinician, who can check your heart with standard tests.
Can my clinician work out PhenoAge from my labs?
The nine inputs are routine clinical lab tests1, so the raw numbers may already be in your chart. The score itself isn’t part of standard care2. Ask instead what each value says about you.
The bottom line
Biological-age scores are real research tools. Across large groups, they predict who is more likely to get sick or die. But they measure different things, they rest on different reference groups, and no expert body says one person’s score should change their treatment.
If a report is already in your hands, find out what kind of number it is, ask the questions in the decoder, and take any worry to a clinician. Then put your energy into the measures with known meaning: blood pressure, blood sugar, kidney tests, fitness, walking speed and grip.
Related reading
About this article
This article was researched using peer-reviewed papers in Aging, Cell, Nature Aging and Nature Medicine, NIH and university summaries, an American Heart Association statement and meeting report, a regulatory journal and reports on FDA actions, all listed below. It was reviewed in October 2026. It is general education and not medical, legal or financial advice.
Sources
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- Moqri M, Herzog C, Poganik JR, et al., Biomarkers of Aging Consortium. “Biomarkers of aging for the identification and evaluation of longevity interventions.” Cell, 2023;186:3758–3775 (copy hosted by UConn Center on Aging). health.uconn.edu
- Herzog CMS, Goeminne LJE, Poganik JR, et al., Biomarkers of Aging Consortium. “Challenges and recommendations for the translation of biomarkers of aging.” Nature Aging, 2024 (Leiden University repository). scholarlypublications.universiteitleiden.nl
- Moqri M, Herzog C, Poganik JR, et al. “Validation of biomarkers of aging.” Nature Medicine, 2024;30:360–372 (Leiden University repository). scholarlypublications.universiteitleiden.nl
- National Institutes of Health. “Tracking organ aging and disease” (on Oh HS, et al., “Organ aging signatures in the plasma proteome track health and disease,” Nature, 2023). NIH Research Matters, January 9, 2024. nih.gov
- Oh HS, Le Guen Y, Rappoport N, et al. “Plasma proteomics links brain and immune system aging with healthspan and longevity.” Nature Medicine, 2025 (Stanford Knight Initiative for Brain Resilience publication summary). brainresilience.stanford.edu
- American Heart Association. “Heart Health Linked to Slower Aging” (news release on a preliminary study presented at Scientific Sessions 2023), republished by Neuroscience News, November 2023. neurosciencenews.com
- Craig A. “An exercise in good health” (on Ross R, et al., “Importance of Assessing Cardiorespiratory Fitness in Clinical Practice: A Case for Fitness as a Clinical Vital Sign,” AHA scientific statement, Circulation, 2016). Queen’s Gazette, November 28, 2016. queensu.ca
- Bluvas E. News article on the AHA scientific statement on cardiorespiratory fitness as a clinical vital sign, co-authored by Arnold School researchers. University of South Carolina Arnold School of Public Health, December 12, 2016.
- AABB. “FDA Formally Vacates LDT Final Rule.” AABB News, September 19, 2025. aabb.org
- Clinical Lab Products. “FDA Withdraws Final Rule Regulating Lab-Developed Tests as Medical Devices.” CLP Magazine, September 22, 2025. clpmag.com
- Clinical Lab Products. Report on FDA’s notice of intent to rescind its laboratory-developed test rule. CLP Magazine, 2025. clpmag.com
- Shapo N, Masar MS III. “Modern Regulatory Frameworks for the Use of Genetic and Epigenetic Underwriting Technology in Life Insurance.” Journal of Insurance Regulation, National Association of Insurance Commissioners, 2021. doi.org
- HealthDay. “AHA: High Cardiovascular Health Linked to Lower Phenotypic Age” (on a preliminary study by Columbia University researchers, senior author Makarem N, presented at American Heart Association Scientific Sessions 2023). HealthDay, November 2023. healthday.com