The Big 5 of longevity testing

You can’t track everything. And you shouldn’t try.

But when it comes to blood work, a handful of biomarkers rise above the noise.

These aren’t the usual suspects like a full lipid panel or CBC… that’s technically cheating.

We’re talking about five specific biomarkers that punch far above their weight: labs that connect multiple systems, reveal trouble years before symptoms, and actually change what you do next.

Each one is a lever. Pull it, and more than one system moves.

This is our short list chosen with intention. Because we believe in testing smarter, not more - targeted labs that give you clarity instead of overwhelm.

Think we missed a big one? Tell us. We’re ready to be challenged.

hs-CRP — Your Body’s Smoke Alarm

What it is: C-reactive protein is an acute-phase protein made by the liver when the immune system senses injury, infection, or stress. It helps tag damaged cells and microbes for cleanup.

The high-sensitivity test detects even small, ongoing inflammation - the kind linked to chronic, low-grade inflammation.

Why we’re choosing it: Inflammation underlies nearly every major chronic condition, from heart disease and memory decline to joint pain and slower recovery.

While standard CRP only rises when the body is in crisis, hs-CRP captures the quieter, ongoing inflammation that fuels atherosclerosis, neurodegeneration, and accelerated aging. It acts like an integrative signal, condensing stress inputs from metabolism, immunity, and lifestyle into a single, easy-to-measure number.

Think of hs-CRP as a smoke alarm:

• Standard CRP: only blares when the kitchen is on fire.

• hs-CRP: detects the faintest wisp of smoke - early, subtle, and actionable.

We’re choosing hs-CRP over:

• ESR (Erythrocyte Sedimentation Rate): too sluggish and nonspecific for small changes.

• Cytokines (IL-6, TNF-α): useful in research, but unstable and impractical for routine tracking.

• White Blood Cell Count: good for major immune events, but blind to subtle inflammation.

For overall health and longevity, you want that smoke alarm quiet most of the time. Not just “below 3 mg/L” (the conventional heart disease threshold), but ideally closer to 0.5 mg/L or lower. The less background inflammation you carry across decades, the slower your biological clock ticks.

ApoB — Counting the Real Risk

What it is: Apolipoprotein B is the protein tag on every cholesterol-carrying particle that can lodge in artery walls; LDL, VLDL, IDL, and Lp(a). Each particle has one ApoB, count ApoB, and you know exactly how many of these particles are in circulation.

Why we’re choosing it: Plaque risk depends on the number of particles, not just how much cholesterol each carries. You can have “normal” LDL-C but still too many particles silently driving atherosclerosis. ApoB reflects the efficiency of your whole lipid transport system - how your liver packages fat, how your metabolism handles it, and how that impacts vascular health.

Think of it like traffic. LDL-C tells you how much cargo is in each truck. ApoB counts the trucks themselves. Too many on the road? Congestion, collisions, damage, even if each truck is carrying less cargo.

We’re choosing ApoB over:

• LDL-C: The traditional go-to, but misses hidden high particle counts.

• Non-HDL cholesterol: Closer, but still an indirect estimate.

• Total cholesterol: Outdated as a risk measure; ignores particle number and size entirely.

For long-term health, you want that “truck count” as low as safely possible. Think of <60 mg/dL as an ideal target (and even lower if you already face cardiovascular risk). The fewer atherogenic particles on the road, the less wear and tear your arteries collect across the decades.

Fasting Insulin — The Early Metabolic Drift Detector

What it is: Insulin is the hormone that helps cells take up glucose from the blood. A fasting insulin test shows how much is needed to keep your blood sugar in the normal range after an overnight fast. This level rises early when metabolic health begins to decline, often years before blood sugar or HbA1c levels change.

Why we’re choosing it: Insulin resistance (the reduced ability of cells to respond to insulin) is often the first metabolic problem, preceding high blood sugar. Elevated fasting insulin signals this early impairment and can act as an early warning sign for future diabetes and metabolic dysfunction.

Insulin regulates multiple systems beyond glucose (fat storage, inflammation, hormone balance) and elevated fasting insulin also links to arterial stiffening, fatty liver, and chronic inflammation. It shifts nutrient-sensing pathways from repair toward growth states, contributing to long-term damage.

Think of it like a thermostat. You want the heating system to work efficiently with minimal effort. If it’s blasting full power just to keep the room warm, something’s wrong - even if the temperature still looks fine.

We’re choosing fasting insulin over:

• HbA1c: reflects average glucose over months but lags behind insulin changes.

• Fasting glucose: fluctuates daily and often remains normal early in insulin resistance.

• eAG (estimated average glucose): derived from HbA1c and similarly delayed. By the time it changes, insulin has usually been elevated for a while.

For optimal health, you want that “thermostat setting” low and steady, not just “under 25 μIU/mL” like some lab cutoffs, but ideally in the range of 2–5 μIU/mL. The less effort your body expends managing blood sugar, the more energy is available for repair, resilience, and daily performance.

Ferritin — Your Iron Savings Account

What it is: Ferritin is the primary iron storage protein in the body, acting as a vault that safely stores excess iron inside cells and releases it when needed. Unlike serum iron, which reflects iron circulating at the moment, ferritin reveals total iron reserves. It stores iron in a non-toxic, soluble form, preventing free iron from generating harmful reactive oxygen species.

But here’s the twist: ferritin is also an acute phase reactant, meaning its blood levels rise during inflammation regardless of iron status. Elevated ferritin can indicate iron overload or it could just be your immune system in fight mode.

Why we’re choosing it: Iron is a double-edged sword: too little causes anemia and fatigue, while too much drives oxidative stress, tissue damage, and chronic disease risk.

Ferritin isn’t just about iron supply, it also connects to mitochondrial energy, immune function, brain health, and hormone production. Because the body recycles iron carefully but has no active way to eliminate the excess, even small imbalances can disrupt these systems and persist unless addressed.

We’re choosing ferritin over:

• Serum iron: a snapshot of today’s iron, but changes meal-to-meal.

• Transferrin saturation: useful diagnostically but less direct for tracking long-term balance.

• TIBC (Total Iron-Binding Capacity): Helpful in context, but not as straightforward for tracking optimal ranges.

For functional health, aim to keep your “iron account” balanced, not just above the clinical anemia cutoff of 15 ng/mL, but ideally closer to 40–70 ng/mL for women and 50–100 ng/mL for men, depending on context. This range supports efficient oxygen delivery without tipping into iron overload or oxidative stress.

IGF-1 — The Growth & Repair Balancer

What it is: IGF-1 is the signal downstream of growth hormone, telling cells throughout the body to grow, repair, and survive — from muscle and bone to brain and blood vessels. Almost every tissue listens to IGF-1.

Why we’re choosing it: IGF-1 provides a snapshot of your body’s growth–repair balance by reflecting hormonal, nutritional, and metabolic signals. Low levels increase risks of muscle loss, fragile bones, poor healing, and frailty — all key contributors to aging and functional decline. High levels overstimulate growth pathways like mTOR, which are linked to accelerated aging, oxidative stress, and increased cancer risk. Screening IGF-1 identifies these risks early, allowing lifestyle, nutrition, or medical interventions to preserve muscle, support repair, and reduce aging-related decline and disease.

From a systems biology lens, IGF-1 weaves together:

• Growth hormone pulses from your brain

• Protein and calorie availability

• Training load and recovery

• Hormonal signals from thyroid, sex hormones, and cortisol

It serves as a real-time reflection of how your nutrient-sensing network is set, coordinating these diverse inputs to regulate growth and repair processes.

We’re choosing IGF-1 over:

• Growth hormone: Spikes and crashes all day, so one reading is unreliable.

• Tissue-specific anabolic hormones (e.g., testosterone): Important individually, but IGF-1 reflects the integrated balance of the whole system.

For functional health, aim for an age- and sex-adjusted mid-range level—generally between 200-300 ng/mL. This range supports mitochondrial function, vitality, cognitive health, sleep quality, muscle growth, and recovery, hitting the sweet spot where repair thrives without overstimulating growth pathways.

That’s our top five - biomarkers that carry more weight than most.

They offer cross-system insight, catch early signs of trouble, and give you actionable levers to pull. But your story might be different.

Maybe vitamin D is your must-test.

Maybe HbA1c holds the key for you.

Maybe there’s a wildcard marker you rely on… or one you wish Superpower offered.

So here’s the question: Which biomarkers do you track? And if you could swap out one of ours, which one would it be?

P.S Tash, our resident newsletter nerd, also ranked her top 5 (with a fantasy football twist). Check out what made the cut here.

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