Which blood biomarkers actually matter for longevity?

The blood biomarkers that actually matter for longevity are those that robustly predict all-cause mortality and healthspan by measuring metabolic health, cardiovascular risk, and systemic inflammation. The most critical and consistently validated markers are HbA1c (blood sugar control), ApoB (atherogenic particle count), hs-CRP (chronic inflammation), and Lipoprotein(a) (genetic heart disease risk).

1. Metabolic Health (The Strongest Predictor of Aging)

HbA1c is widely considered the gold standard for longevity because it reflects average blood glucose over 2–3 months, not just a single spike [2][6].

• Why it matters: Even within the "normal" range, every 0.1% increase in HbA1c above 5.0% is linked to higher all-cause mortality [3].
• Supporting markers: Fasting glucose and fasting insulin (or C-peptide) help identify hidden insulin resistance before HbA1c rises [8][15]. The Triglyceride-Glucose (TyG) index is also a powerful metric for metabolic dysfunction [8].

2. Cardiovascular Risk (Beyond Standard LDL)

Standard LDL cholesterol is often insufficient; experts prioritize ApoB and Lp(a) for their superior accuracy in predicting heart disease, the leading cause of death [1][5].

• ApoB (Apolipoprotein B): This is the most accurate marker for cardiovascular risk because it counts the total number of atherogenic particles (particles that clog arteries) [5]. Ideally, levels should be <80 mg/dL, with many longevity experts aiming for <60 mg/dL [4].
• Lp(a) (Lipoprotein a): A genetically determined, major independent risk factor for heart disease that standard statins often miss [1][4]. The ideal target is <30 mg/dL (ideally <10) [4].
• sdLDL (Small Dense LDL): More atherogenic than standard LDL and strongly linked to longevity risks [4].

3. Systemic Inflammation ("Inflammaging")

Chronic, low-grade inflammation drives nearly every age-related disease, making hs-CRP a critical longevity marker [1][8].

• hs-CRP: Predicts cardiovascular events and all-cause mortality in large cohorts. The ideal target is <1.0 mg/L, with many experts aiming for <0.5 mg/L [4][8].
• IL-6 (Interleukin-6): A more direct pro-inflammatory cytokine that tracks immune activation and predicts mortality in older adults, though it is less common in routine tests [4][15].
• Other inflammatory markers: Fibrinogen, Ferritin (iron storage/inflammation), and ESR are also tracked but are generally less specific than hs-CRP [4].

4. Organ Function & Nutrient Status

Longevity requires maintaining functional reserve in the liver and kidneys, alongside adequate nutrient levels to prevent molecular aging acceleration [5][8].

• Kidney Function: Creatinine and eGFR (estimated glomerular filtration rate) are essential; lower creatinine levels have been linked to survival in old age [4][7]. Cystatin C is a more sensitive kidney marker [8][15].
• Liver Function: ALT, AST, and GGT indicate liver health; lower levels of GGT and ASAT were associated with reaching 100 years of age [7][8].
• Nutrients: Deficiencies in Vitamin D, Vitamin B12, Magnesium, and Ferritin impair cellular function [8]. Homocysteine (<10 umol/L) is a key marker for methylation status and vascular risk [4][14].

5. Emerging & Specialized Markers

• GDF15 (Growth Differentiation Factor 15): A robust proteomic biomarker identified in recent studies that predicts accelerated multimorbidity and mortality [10].
• Albumin: Higher levels are linked to improved survival in old age [7][9].
• Epigenetic Clocks (GrimAge/PhenoAge): These use DNA methylation patterns from blood to estimate "clinical phenotypic age," showing a higher association with time-to-death than traditional biomarkers [17].

Summary of Target Ranges for Longevity

Note: While "total cholesterol" and "iron" were associated with centenarians in one specific study, this is likely context-dependent; most longevity experts prioritize low ApoB and controlled inflammation over high total cholesterol or iron [7][5].