The biomarker library
Supplements are inputs. Biomarkers are outputs. These are the numbers worth tracking, with optimal ranges (sourced, not just lab ranges), how to move them, and which goals and stacks they connect to.
Foundational
VO2 Max
The maximum rate your body can use oxygen during intense exercise, usually reported in ml/kg/min. It reflects the combined capacity of your lungs, heart, blood, and muscles.
Optimal ranges and how to improve it →
Heart Rate Variability (HRV)
The variation in time between consecutive heartbeats, usually reported as RMSSD in milliseconds. It reflects autonomic nervous system balance between sympathetic and parasympathetic activity.
Optimal ranges and how to improve it →
Resting Heart Rate
The number of heartbeats per minute while at complete rest, ideally measured first thing in the morning. A proxy for cardiovascular efficiency.
Optimal ranges and how to improve it →
Blood Oxygen Saturation (SpO2)
The percentage of hemoglobin in arterial blood carrying oxygen, measured noninvasively by a pulse oximeter. A basic window into respiratory and circulatory function.
Optimal ranges and how to improve it →
Grip Strength
Maximum hand grip force measured with a dynamometer, in kilograms. A simple proxy for total-body muscle strength and frailty.
Optimal ranges and how to improve it →
Walking Speed
Usual gait speed over a short distance (e.g. 4 meters), in meters per second. It integrates strength, balance, coordination, and cardiovascular capacity.
Optimal ranges and how to improve it →
DEXA Lean Mass (ALMI)
Appendicular lean mass index (ALMI): limb lean mass in kg divided by height in meters squared, from a DEXA body-composition scan. A purer measure of muscle mass than total weight or BMI.
Optimal ranges and how to improve it →
Blood Pressure
The force of blood against arterial walls, reported as systolic over diastolic in mmHg. The most widely tracked cardiovascular vital sign.
Optimal ranges and how to improve it →
Fasting Insulin
Insulin concentration in blood after an overnight fast, in uIU/mL. A direct read on how hard your body works to keep blood sugar normal.
Optimal ranges and how to improve it →
HbA1c
The percentage of hemoglobin with glucose attached, reflecting average blood sugar over the prior 2 to 3 months. The standard diagnostic test for prediabetes and diabetes.
Optimal ranges and how to improve it →
Fasting Glucose
Blood sugar after at least 8 hours without calories, in mg/dL. A snapshot of overnight glucose regulation by the liver.
Optimal ranges and how to improve it →
Triglycerides
The main form of fat circulating in blood, measured fasting in mg/dL. Rises with excess calorie, carbohydrate, and alcohol intake.
Optimal ranges and how to improve it →
ApoB
Apolipoprotein B, the protein on every atherogenic particle (LDL, VLDL, Lp(a)), in mg/dL. One ApoB equals one artery-clogging particle, making it a direct count of cardiovascular risk particles.
Optimal ranges and how to improve it →
Lipoprotein(a)
A genetically determined, sticky variant of LDL reported in nmol/L or mg/dL. Levels are set at birth and barely move with lifestyle.
Optimal ranges and how to improve it →
hs-CRP
High-sensitivity C-reactive protein, a blood marker of systemic inflammation, in mg/L. The high-sensitivity version detects low-grade chronic inflammation.
Optimal ranges and how to improve it →
Uric Acid
A byproduct of purine and fructose metabolism, in mg/dL. Best known for gout, but also a marker of metabolic dysfunction.
Optimal ranges and how to improve it →
Advanced
Biological Age Clocks (PhenoAge, GrimAge)
Second-generation epigenetic clocks estimated from DNA methylation in blood. PhenoAge (Levine 2018) was trained on clinical biomarkers; GrimAge (Lu 2019) on time-to-death data. They estimate biological rather than chronological age.
Optimal ranges and how to improve it →
Kidney Function (eGFR, Cystatin C)
Estimated glomerular filtration rate (eGFR) in ml/min/1.73m2, the standard measure of kidney filtering capacity. Cystatin C is a muscle-independent marker that refines the estimate.
Optimal ranges and how to improve it →
Liver Enzymes (ALT, AST, GGT)
ALT and AST are enzymes released when liver cells are stressed or damaged, in U/L. GGT rises with bile-duct stress and alcohol use. Together they screen for fatty liver and liver injury.
Optimal ranges and how to improve it →
Testosterone (Total and Free)
The primary male sex hormone, reported as total testosterone in ng/dL and free (bioavailable) testosterone in pg/mL. Measure fasting in the morning, when levels peak.
Optimal ranges and how to improve it →
DHEA-S
Dehydroepiandrosterone sulfate, the most abundant circulating steroid, made by the adrenal glands. A precursor to testosterone and estrogen that peaks in the 20s and falls steadily with age.
Optimal ranges and how to improve it →
Estradiol (Women)
The most potent estrogen, in pg/mL. In premenopausal women it cycles dramatically across the menstrual cycle; after menopause it falls to very low levels.
Optimal ranges and how to improve it →
Vitamin D Status (25-OH-D)
Blood 25-hydroxyvitamin D, the storage form, in ng/mL. The standard marker of vitamin D status from sun, food, and supplements.
Optimal ranges and how to improve it →
Omega-3 Index
The percentage of EPA plus DHA in red blood cell membranes. A long-term marker of omega-3 status, reflecting months of intake rather than yesterday's meal.
Optimal ranges and how to improve it →
Homocysteine
An amino acid intermediate in methionine metabolism, in umol/L. Rises when B-vitamin (B12, folate, B6) status is poor or methylation is impaired.
Optimal ranges and how to improve it →
Educational information, not medical advice. Biomarker targets interact with age, sex, medications, and conditions. Talk to your doctor before acting on any number here.