Biomarkers
Measurable indicators of biological age, health span, and metabolic status.
Large human RCTs or meta-analyses
25-Hydroxyvitamin D (Vitamin D Status)
The standard blood test for vitamin D status; correcting deficiency matters for bone health, but large RCTs have not confirmed broader cancer or cardiovascular prevention claims.
Small human pilot studies or cohorts
8-OHdG (8-hydroxy-2'-deoxyguanosine)
An oxidised DNA base excreted in urine; the most widely used quantitative marker of oxidative damage to DNA.
Small human pilot studies or cohorts
Alpha-Klotho (Circulating)
Serum concentration of the soluble anti-aging protein alpha-Klotho, which falls with age and predicts all-cause mortality in older adults.
Medium human RCTs or systematic reviews
Apolipoprotein B (ApoB)
The structural protein on every atherogenic lipoprotein particle, directly counting cardiovascular risk-carrying particles better than LDL cholesterol alone.
Medium human RCTs or systematic reviews
Body Composition (Fat Mass, Lean Mass, Visceral Fat)
The muscle-to-fat and fat-distribution profile of the body, where the combination of low muscle mass and high visceral fat (sarcopenic obesity) carries dramatically higher mortality risk than either alone.
Small human pilot studies or cohorts
CD4/CD8 T-Cell Ratio
The ratio of helper to cytotoxic T cells in peripheral blood; inversion below 1.0 marks immunosenescence and tracked with higher mortality in Swedish octogenarian cohorts.
Small human pilot studies or cohorts
Carotid Intima-Media Thickness (IMT)
An ultrasound measurement of carotid artery wall thickness used as a marker of subclinical atherosclerosis, though its added predictive value over standard risk calculators is modest.
Medium human RCTs or systematic reviews
Coronary Artery Calcium (CAC) Score
A CT scan measurement of calcified coronary plaque that directly images atherosclerosis and meaningfully reclassifies cardiovascular risk beyond standard risk calculators.
Large human RCTs or meta-analyses
25-Hydroxyvitamin D (Vitamin D Status)
The standard blood test for vitamin D status; correcting deficiency matters for bone health, but large RCTs have not confirmed broader cancer or cardiovascular prevention claims.
Small human pilot studies or cohorts
8-OHdG (8-hydroxy-2'-deoxyguanosine)
An oxidised DNA base excreted in urine; the most widely used quantitative marker of oxidative damage to DNA.
Small human pilot studies or cohorts
Alpha-Klotho (Circulating)
Serum concentration of the soluble anti-aging protein alpha-Klotho, which falls with age and predicts all-cause mortality in older adults.
Medium human RCTs or systematic reviews
Apolipoprotein B (ApoB)
The structural protein on every atherogenic lipoprotein particle, directly counting cardiovascular risk-carrying particles better than LDL cholesterol alone.
Medium human RCTs or systematic reviews
Body Composition (Fat Mass, Lean Mass, Visceral Fat)
The muscle-to-fat and fat-distribution profile of the body, where the combination of low muscle mass and high visceral fat (sarcopenic obesity) carries dramatically higher mortality risk than either alone.
Small human pilot studies or cohorts
CD4/CD8 T-Cell Ratio
The ratio of helper to cytotoxic T cells in peripheral blood; inversion below 1.0 marks immunosenescence and tracked with higher mortality in Swedish octogenarian cohorts.
Small human pilot studies or cohorts
Carotid Intima-Media Thickness (IMT)
An ultrasound measurement of carotid artery wall thickness used as a marker of subclinical atherosclerosis, though its added predictive value over standard risk calculators is modest.
Medium human RCTs or systematic reviews
Coronary Artery Calcium (CAC) Score
A CT scan measurement of calcified coronary plaque that directly images atherosclerosis and meaningfully reclassifies cardiovascular risk beyond standard risk calculators.
Medium human RCTs or systematic reviews
DunedinPACE (Pace of Aging Clock)
A DNA methylation measure of the current rate of biological aging, built from 19 organ-system biomarkers tracked longitudinally in the Dunedin birth cohort.
Small human pilot studies or cohorts
FGF21 (Fibroblast Growth Factor 21)
A liver-derived mitokine released during fasting and mitochondrial stress; blood levels rise with age and with metabolic disease rather than falling.
Medium human RCTs or systematic reviews
Fasting Insulin
Serum insulin after an 8-12 hour fast; it rises years before fasting glucose does and is the input to HOMA-IR.
Medium human RCTs or systematic reviews
Frailty Index
A overall score counting accumulated health deficits across many domains that predicts mortality more accurately than any single biomarker in the oldest-old.
Medium human RCTs or systematic reviews
GDF-15 (Growth Differentiation Factor 15)
A mitochondrial and cellular stress cytokine that is among the strongest single blood predictors of all-cause mortality in older adults.
Medium human RCTs or systematic reviews
Gait Speed
A simple timed walking-speed test in older adults that predicts survival about as accurately as detailed clinical risk models combining multiple disease and lifestyle factors.
n=1 self-experiments or animal studies
GlycanAge (IgG Glycosylation Age)
A commercial biological-age test based on antibody sugar-chain patterns reflecting immune inflammatory aging, with a thinner independent evidence base than established epigenetic clocks.
Medium human RCTs or systematic reviews
GrimAge (DNAm GrimAge Epigenetic Clock)
A second-generation epigenetic clock trained directly on mortality data that outperforms earlier clocks at predicting death, heart disease, and cancer risk in cohort studies.
Medium human RCTs or systematic reviews
Grip Strength
A simple handheld dynamometer test that predicts all-cause mortality and cardiovascular events more strongly than systolic blood pressure in large cohort studies.
Small human pilot studies or cohorts
HDL Cholesterol (HDL-C)
Cholesterol carried by high-density lipoprotein particles, historically called protective, but pharmaceutical trials raising it have repeatedly failed to reduce cardiovascular events.
Medium human RCTs or systematic reviews
HOMA-IR
A calculated index from fasting glucose and insulin that estimates insulin resistance, the metabolic driver behind type 2 diabetes and a core aging-related biomarker.
Medium human RCTs or systematic reviews
HbA1c (Glycated Hemoglobin)
A blood test reflecting average glucose exposure over 2-3 months, used to diagnose diabetes and track long-term glycemic control.
Medium human RCTs or systematic reviews
Heart Rate Variability (HRV)
The beat-to-beat variation in heart timing reflecting autonomic nervous system balance; lower HRV consistently predicts higher mortality across general and cardiovascular disease populations.
Small human pilot studies or cohorts
Homocysteine
An amino acid byproduct linked to cardiovascular and cognitive risk in observational studies, but B-vitamin trials lowering it have not reduced heart attacks or strokes.
Medium human RCTs or systematic reviews
Horvath Clock (DNA Methylation Age)
The first widely used epigenetic clock estimates biological age from DNA methylation patterns and predicts mortality risk independent of chronological age.
Medium human RCTs or systematic reviews
Interleukin-6 (IL-6)
A key inflammaging cytokine whose chronic elevation independently and consistently predicts mortality across multiple large cohorts of older adults.
Large human RCTs or meta-analyses
LDL Cholesterol (LDL-C)
The cholesterol carried by low-density lipoprotein particles, a well-established causal driver of atherosclerotic cardiovascular disease.
Large human RCTs or meta-analyses
Lipoprotein(a) [Lp(a)]
A largely genetically fixed atherogenic particle; levels above the 95th percentile carry roughly 2.6 times the risk of myocardial infarction.
Small human pilot studies or cohorts
NAD+ (Blood/Tissue Levels)
A cellular energy coenzyme that declines with age in multiple tissues; NR and NMN reliably raise blood NAD+ levels, but functional or lifespan benefits remain unproven in large human trials.
Small human pilot studies or cohorts
OMICmAge
A next-generation multi-omics biological age score that integrates DNA methylation, clinical labs, and electronic medical record data, published in Nature Aging in 2026.
Medium human RCTs or systematic reviews
Omega-3 Index
The percentage of EPA and DHA in red blood cell membranes, a stable biomarker of long-term omega-3 status linked to cardiovascular risk.
n=1 self-experiments or animal studies
Oral Microbiome Age
A biological age score built from oral (mouth) microbiome sequencing that predicts host health and chronological age, published in Nature Communications in 2026.
Medium human RCTs or systematic reviews
PhenoAge (DNAm PhenoAge Epigenetic Clock)
A second-generation epigenetic clock built from nine clinical mortality markers that predicts all-cause mortality, cancer, cardiovascular disease, and Alzheimer's risk in cohort studies.
Medium human RCTs or systematic reviews
Proteomic Aging Clock (Organ-Specific)
A blood proteomics-based biological age score built from ~3,000 Olink-measured proteins, developed and validated across 48,000+ participants in three continents, that predicts disease and mortality organ-by-organ.
Medium human RCTs or systematic reviews
Resting Heart Rate (RHR)
The number of heartbeats per minute at rest; higher values and rising trends over time both independently predict greater mortality risk across decades of Framingham and related cohort data.
Small human pilot studies or cohorts
Retinal Age (Deep-Learning Fundus Photography)
A deep-learning biological age score derived from a standard retinal fundus photograph, validated in cross-population cohorts and associated with mortality and cardiovascular disease.
Medium human RCTs or systematic reviews
Telomere Length (Leukocyte)
A modest, consistent predictor of mortality across large pooled cohorts, but with an effect size much smaller than established risk factors and no proven intervention to lengthen it.
Small human pilot studies or cohorts
Tumor Necrosis Factor-alpha (TNF-alpha)
A pro-inflammatory cytokine with mortality associations that shift meaningfully by sex and age, dominant in centenarian cohorts but less consistent than IL-6 in younger-old adults.
Medium human RCTs or systematic reviews
VO2max (Maximal Oxygen Uptake)
The gold-standard measure of cardiorespiratory fitness; higher VO2max predicts dramatically lower all-cause mortality with no evidence of harm even at extremely high fitness levels.
Medium human RCTs or systematic reviews
hs-CRP (High-Sensitivity C-Reactive Protein)
A sensitive blood marker of low-grade systemic inflammation that independently predicts cardiovascular events and all-cause mortality.