By Dr. Brandon Bright, DAOM, LAc · Doctor of Acupuncture & Oriental Medicine · Functional Medicine University-certified · Longevity Protocol Specialist · Tustin, CA · Last reviewed: June 2, 2026
In 2026, biological age testing splits into two real categories: epigenetic clocks (Horvath, TruDiagnostic, GrimAge) measure methylation patterns and typically cost $200–$500 per test; biomarker-derived clocks (Function Health, Levine PhenoAge) calculate age from comprehensive bloodwork at lower cost. Neither is “wrong,” but they measure different things, and most patients should test both at least once for calibration.
Why This Question Exists Right Now
Biological age testing went from a researcher-only tool to a consumer product in the past five years. As of mid-2026, there are at least eight ways to get a “biological age” number, they don’t agree with each other, and the marketing language across the category is loose enough that patients are reasonably confused about what they’re actually buying. This guide is the version I wish existed when patients started bringing me TruDiagnostic results in 2023.
To save time: there is no “best” biological age test for everyone. There’s a correct test for your specific situation, and choosing it requires understanding what each test actually measures.
The Two Real Categories
Category 1: Epigenetic Clocks (Methylation-Based)
What they measure: DNA methylation patterns at specific CpG sites known to correlate with chronological aging. Trained on large reference populations to predict age from methylation signatures.
The major options:
- Horvath clock (2013) — Original, multi-tissue, conservative. Used in research. Available through several commercial labs.
- Hannum clock (2013) — Blood-specific. Often used alongside Horvath for cross-validation.
- PhenoAge (Levine, 2018) — Calibrated to predict morbidity and mortality outcomes more directly than chronological-age prediction.
- GrimAge (2019) — Most strongly linked to mortality risk and lifespan in published research. Available through TruDiagnostic and a few others.
- DunedinPACE (2022) — Measures rate of aging, not just age — particularly useful for intervention tracking because it’s more sensitive to short-term changes.
What they cost: Typically $200–$500 per test. TruDiagnostic, EpiAging, Elysium, and a few others offer consumer-facing versions.
What they’re good for: Establishing baseline biological-age signature, tracking long-term trends across 12–24+ month windows, evaluating whether an intervention is moving methylation patterns.
Where they’re noisy: Short-term variation can be substantial — methylation patterns can shift with acute illness, sleep deprivation, recent intense exercise, and other transient factors. Single-test readings are less reliable than trend lines across 3–4 tests over 6–12 months. The category-wide test-retest reliability is moderate (correlation coefficients typically 0.7–0.9 for the better-validated clocks; lower for the newer ones).
Category 2: Biomarker-Derived Age (Bloodwork-Based)
What they measure: Age calculated from comprehensive bloodwork using validated algorithms. The most-used is Levine’s PhenoAge biomarker formula, which uses nine standard lab markers (albumin, creatinine, glucose, CRP, lymphocyte percentage, MCV, RDW, alkaline phosphatase, WBC).
The major options:
- Function Health’s biological age — Uses PhenoAge algorithm applied to their comprehensive 100+ marker panel. Twice-yearly testing structure built in.
- InsideTracker’s InnerAge — Proprietary algorithm using their lab panel. Targets a younger lifestyle-focused user base.
- Levine PhenoAge (research) — The underlying algorithm Function and others build on. Calculable from standard bloodwork; some patients calculate it themselves.
- Superpower’s biological age — Newer entrant, AI-agent positioning, currently in federal litigation with Function (C.D. Cal. Jan 2026).
What they cost: Effectively free if you’re already doing comprehensive bloodwork — these tools calculate age from data you’d order anyway. Function Health is $499/year for two comprehensive panels including the age calculation.
What they’re good for: More frequent measurement than epigenetic clocks (typically 2–4x per year vs once for epigenetic), tighter integration with actual intervention design (the markers driving the score are also the markers you’d address), better short-term sensitivity to lifestyle changes.
Where they’re noisy: Algorithm-dependent. Two biomarker clocks can give different ages from the same bloodwork. PhenoAge specifically is well-validated for mortality prediction but is less direct as a “rate of biological aging” measure.
Why the Two Categories Don’t Agree
Different tools measure different things. Methylation clocks read epigenetic signatures laid down over years; biomarker clocks read current physiological state. A patient can have an “old” methylation signature (years of cumulative methylation drift) but a “young” biomarker score (currently great inflammation markers, lipids, glucose).
The disagreement isn’t a measurement error — it’s two valid signals about different aspects of aging biology. For most patients running a longevity protocol, knowing both gives you more information than knowing either alone.
How to Actually Use These Tools
A reasonable testing strategy for a patient seriously running a longevity protocol:
Year 1 — Baseline:
- One comprehensive epigenetic test (GrimAge or DunedinPACE preferred for outcome relevance)
- Comprehensive bloodwork with biomarker-derived age (Function Health or equivalent)
- This gives you both signals for baseline calibration
Year 1 — Quarterly:
- Comprehensive bloodwork (Function does this twice a year; some patients run more often)
- Track biomarker-derived age trend across quarters
Year 2 Onward:
- Repeat epigenetic test once a year (annual frequency is reasonable; quarterly is overkill for methylation given test cost)
- Continue quarterly bloodwork
- Compare trends across both categories
What this protocol tells you over 2–3 years: whether your interventions are moving both methylation signatures and current physiological markers. If only one moves, you know which layer your protocol is reaching. If neither moves, the protocol isn’t working and you need different interventions.
What These Tests Miss
Even with both categories tested optimally, biological age testing has structural limitations:
Single-number compression. A “biological age” number compresses extraordinarily complex aging biology into a single value. The aggregation throws away most of the information.
Population-trained algorithms. Clocks are trained on reference populations. If you’re systematically different from the training population (different ancestry, atypical medical history, extreme exercise or supplementation), the prediction may be less accurate for you specifically.
No causation, only correlation. A clock saying you’re “biologically 5 years younger than chronological” doesn’t tell you why or what to do next. The intervention design is a separate step.
The “what to do about it” gap. Most biological age platforms tell you your age, sometimes with general nudges. Translating the result into a specific intervention sequence is where most patients get stuck.
This last gap is specifically what I built AI Longevity Pro to fill. Disclosed conflict-of-interest: I’m the founder of AI Longevity Pro, which entered beta yesterday (Monday June 1, 2026). The app’s specific job is to read your biomarker data (Function Health, TruDiagnostic, and others via Terra integration) and translate the results into combo-aware protocol reasoning anchored in clinical multi-modality work. It doesn’t add to the “what is your age” answer — that question is well-served by Function, TruDiagnostic, and others — it addresses the “what do I do about it” gap that the testing platforms leave open.
→ Join the AI Longevity Pro beta (90-day complimentary period).
How AI Longevity Pro Uses Biological Age Data
For users connecting both epigenetic test data (TruDiagnostic, EpiAging) and bloodwork-derived data (Function Health, InsideTracker), the app:
- Reconciles the two signals into a coherent baseline picture
- Identifies which layer of biology is driving discrepancies between them
- Sequences interventions by priority layer (per the Four Layers of Health framework I use clinically)
- Tracks protocol response across both signal types over time
- Surfaces combo-aware supplement reasoning calibrated to your specific markers
The honest description of what it doesn’t do: it doesn’t replace your clinician, it doesn’t write prescriptions, and it doesn’t have published outcome data yet (Day 2 of beta — expect 12–24 months for comparable validation against Reveri-scale outcomes data).
Practical Recommendations for Different Patient Situations
If you’ve never tested: Start with bloodwork-derived age via Function Health or comparable. Lower cost, more actionable, easier to repeat. Add an epigenetic test in year 2 for cross-validation.
If you’ve already done TruDiagnostic and want to add bloodwork: Function Health is the most-used pairing. Cross-reference the two signals.
If you’re a long-time longevity protocol runner and want intervention-tracking sensitivity: DunedinPACE is the most-sensitive epigenetic measure for short-term protocol response.
If you’re trying to evaluate a specific intervention: Test before and after a defined intervention window (90 days minimum, ideally 6–12 months). Single before-and-after readings are noisy; track for trend.
If you’re confused about what to do with the result: That’s the gap AI Longevity Pro is built for, or a structured first visit with an integrative clinician. The result on its own doesn’t tell you what to change.
Frequently Asked Questions
Which biological age test is most accurate?
No single answer. GrimAge has the strongest published link to mortality outcomes. DunedinPACE is the most sensitive to short-term changes. PhenoAge (and Function Health’s implementation of it) is the most actionable. Test for the question you’re asking.
Is biological age testing worth the money?
Depends on what you’re going to do with the result. If you’re going to test once and forget about it, probably not. If you’re going to use it to calibrate a serious longevity protocol over 2–3 years, yes.
Can I lower my biological age?
Probably, by some metrics, with sustained intervention. Realistic expectations: 0.5–2 years of biological-age improvement per 12-month protocol cycle. Some patients show larger shifts; some show none.
Is Function Health’s biological age legitimate?
Yes. It uses the validated PhenoAge algorithm. The number is real; it just measures one specific aspect of biological aging (biomarker-derived) rather than another (methylation-derived).
Is Bryan Johnson’s protocol going to lower my biological age?
Probably not by following it directly — his protocol is calibrated to his specific baseline. The principle of sustained measurement and intervention is sound; the specific protocol stack doesn’t generalize.
What does AI Longevity Pro test for?
It doesn’t test directly — it integrates with existing test platforms (Function, InsideTracker, TruDiagnostic, etc.) and provides the protocol-reasoning layer on top of the data those platforms already produce.
Dr. Brandon Bright, DAOM, LAc
Holistic and integrative medicine practitioner serving Tustin and patients nationwide.