You've probably heard the phrase "what gets measured gets managed." In healthcare, that's never been more true. While most people focus on the number on the scale, the real indicators of long-term health exist at the molecular level—in your blood.
Biomarkers are measurable biological substances in your body that indicate normal or pathological processes.1 They're the early warning system for disease, the proof that your lifestyle changes are working, and the data points that separate proactive health management from reactive medicine.
The longevity community has zeroed in on a specific set of biomarkers worth tracking. These aren't vanity metrics—they're scientifically-backed predictors of how long you'll live and, more importantly, how well you'll live.
Let's break down the 10 biomarkers that matter most, what they mean, and what you can actually do about them.
Why Biomarker Tracking Matters for Longevity
Before we dive into specifics, it's worth understanding why biomarkers have become central to preventive health strategies. Traditional medicine waits for symptoms. You don't visit the doctor until something hurts or you feel sick. By then, significant damage may have already occurred.
Biomarkers flip this script. They reveal problems before you feel them. An elevated hsCRP can signal inflammation years before a heart attack.2 Elevated fasting glucose can indicate metabolic dysfunction long before a diabetes diagnosis.3 This window of time—sometimes years—is your chance to intervene.
Merios is built on this exact principle. As a biomarker-tracking health score app, it takes your blood test results and combines them with wearable data to give you a complete picture of your health trajectory. Rather than seeing isolated data points, you see how your biomarkers interact with your sleep, exercise, and stress patterns—and how they change over time.
The 10 Essential Longevity Biomarkers
1. HbA1c (Glycated Hemoglobin)
What it measures: Your average blood glucose over the past 2-3 months.4 It's more informative than a single fasting glucose test because it captures your whole-day glucose patterns.5
Optimal range: 5.0-5.4% (for non-diabetics; 5.7-6.4% is the prediabetic range)54
Why it matters: HbA1c is a strong predictor of heart disease, stroke, and death, even in people without diabetes.5 Elevated glucose damages tissues throughout your body through a process called glycation, where sugars bind to proteins and form advanced glycation end products that promote inflammation and blood vessel damage.6 Even if you're not diabetic, an HbA1c in the 5.7-6.0% range is associated with increased cardiovascular risk and cognitive decline.57
How to improve it:
- Reduce refined carbohydrate intake and prioritize low glycemic index foods
- Eat protein and healthy fat with every meal to slow glucose absorption
- Time-restrict eating to a consistent 8-10 hour window
- Move for 10 minutes after meals to improve glucose clearance
- Prioritize sleep; poor sleep disrupts glucose metabolism
2. hsCRP (High-Sensitivity C-Reactive Protein)
What it measures: Inflammation in your bloodstream. Regular CRP tests measure gross inflammation; high-sensitivity CRP detects sub-clinical inflammation you wouldn't otherwise notice.8
Optimal range: Below 1.0 mg/L, the low-risk category; within it, lower is better82
Why it matters: Chronic low-grade inflammation is a silent driver of aging. It contributes to cardiovascular disease, neurodegenerative disease, cancer, and metabolic disease.9 An elevated hsCRP often exists long before symptoms, making it a critical early warning system.
How to improve it:
- Eliminate processed foods
- Increase anti-inflammatory foods: fatty fish, leafy greens, berries, turmeric
- Regular exercise (exercise training lowers CRP)10
- Improve sleep quality and duration
- Manage stress; chronic stress raises CRP
- Consider intermittent fasting (trials show modest anti-inflammatory effects)11
3. Vitamin D
What it measures: Circulating 25-hydroxyvitamin D, the storage form of vitamin D in your body.
Optimal range: Guidelines differ. The National Academies consider 20 ng/mL adequate for most people and found no consistent extra benefit at higher levels;12 the Endocrine Society's 2024 guideline found no clear evidence defining an optimal target.13
Why it matters: Vitamin D is less of a vitamin and more of a hormone that regulates over 200 genes.14 Low levels are linked to higher mortality from all causes and from cancer,15 and to infections, although a causal link has not been clearly established.13 Nearly a quarter of Americans are at risk of deficiency or inadequacy (below 20 ng/mL).16
How to improve it:
- Get 20-30 minutes of midday sun exposure several times per week (season and latitude dependent)
- Eat vitamin D-rich foods: fatty fish, egg yolks, mushrooms exposed to sunlight
- Consider supplementation (1000-4000 IU daily, or higher if deficient; test to confirm)
- Combine with K2 and calcium for optimal bone health
4. Ferritin
What it measures: Your body's iron storage. It's an indirect measure of total body iron and, at high levels, can signal iron overload or inflammation.17
Optimal range: No guideline sets one. Lab reference ranges run roughly 24-336 ng/mL for men and 24-307 ng/mL for women;18 in healthy adults, WHO treats levels above 200 ng/mL (men) or 150 ng/mL (menstruating women) as a possible sign of iron overload.17
Why it matters: Very high ferritin can point to iron overload. Conversely, low ferritin can drain energy even before anemia develops: in women with fatigue and ferritin below 50 ng/mL, iron supplements reduced fatigue.19
How to improve it:
- If high: Reduce red meat intake, donate blood, increase antioxidants (berries, dark chocolate)
- If low: Increase iron-rich foods (red meat, spinach), eat with vitamin C (citrus, peppers)
- Avoid iron supplements unless deficient
- Monitor through regular testing
5. TSH (Thyroid-Stimulating Hormone)
What it measures: Your pituitary's signal to your thyroid to produce thyroid hormones. It's the primary test for thyroid function.
Optimal range: 0.5-2.5 mIU/L, the narrower range some endocrinologists argue for (some functional medicine doctors prefer 1.0-2.0)20
Why it matters: Your thyroid controls metabolism, energy, body temperature, and mood. Even subclinical hypothyroidism (TSH above the reference range, typically 4.5 mIU/L or more, with normal thyroid hormone levels) is associated with higher cardiovascular risk, especially once TSH reaches 10 mIU/L.21 TSH and thyroid antibodies rise with age; monitoring catches problems early.22
How to improve it:
- If hypothyroid: Get adequate selenium, zinc, and iodine (seafood, seaweed)
- Manage stress (cortisol suppresses thyroid function)
- Improve sleep quality
- Address nutrient deficiencies; B vitamins and iron support thyroid health
- If TSH is elevated, consult an endocrinologist
6. LDL-P or ApoB (LDL Particle Count or Apolipoprotein B)
What it measures: The number of LDL cholesterol particles in your bloodstream (not the amount of cholesterol). This is more predictive than total cholesterol or even LDL-C.23
Optimal range: For ApoB, European guidelines set goals below 100 mg/dL at moderate cardiovascular risk, below 80 mg/dL at high risk, and below 65 mg/dL at very high risk24
Why it matters: You can have "normal" LDL cholesterol and still have a high particle count—meaning more atherogenic particles damaging your arteries. This is a major blind spot in conventional medicine. ApoB is increasingly the preferred marker; it's a single test that captures all atherogenic particles.23
How to improve it:
- Reduce refined carbohydrates and added sugars
- Increase soluble fiber (oats, beans, flaxseeds)
- Add plant sterols and stanols to diet (found in some fortified foods)
- Exercise regularly (strength and aerobic training both help)
- Don't fear healthy fats; focus on particle count, not fat quantity
7. Testosterone / Estradiol
What it measures: Sex hormone levels, which decline with age.
Reference range (men): Total testosterone 264-916 ng/dL (the harmonized range for healthy young men);25 free testosterone ranges vary by lab and method Reference range (women): Estradiol roughly 10-300 pg/mL before menopause, varying across the cycle, and below 10 pg/mL after menopause; total testosterone 18-54 ng/dL18
Why it matters: Testosterone and estradiol regulate muscle mass, bone density, mental health, sexual function, and metabolic health. Both men and women need both hormones.
How to improve it:
- Strength training (builds muscle and stimulates hormone production)
- Adequate protein intake (essential for hormone synthesis)
- Manage weight; excess body fat increases estrogen dysregulation
- Sleep 7-9 hours nightly (hormones are produced during sleep)
- Reduce endocrine-disrupting chemicals (plastics, pesticides)
- Manage cortisol; chronic stress suppresses sex hormones
8. DHEA-S (Dehydroepiandrosterone Sulfate)
What it measures: Your body's most abundant steroid hormone, a precursor to testosterone and estrogen.
Reference range: About 89-457 μg/dL for men and 44-332 μg/dL for women (varies by age and sex; declines with age)18
Why it matters: DHEA-S falls with age, and low levels predict higher mortality in older men.26 But in a two-year trial in older adults, DHEA supplements had no meaningful effect on body composition, physical performance, insulin sensitivity, or quality of life.27
How to improve it:
- Regular intense exercise (especially strength training and HIIT)
- Adequate sleep
- Manage stress; chronic stress depletes DHEA-S
- Nutrient sufficiency; B vitamins support production
- Supplement with DHEA only if genuinely deficient (requires testing and medical guidance)
9. Homocysteine
What it measures: An amino acid byproduct of methionine metabolism. Elevated levels are a modest, independent cardiovascular risk factor.28
Optimal range: Toward the low end of the 5-15 μmol/L reference range; lower levels go with lower risk1828
Why it matters: High homocysteine is associated with damaged blood vessel walls and atherosclerosis. It's a predictor of heart attack and stroke that's often overlooked. Interestingly, homocysteine is very responsive to B vitamins, making it one of the easiest biomarkers to improve, although lowering it with B vitamins has not been shown to prevent heart attacks.29
How to improve it:
- B6, B12, and folate directly lower homocysteine
- Eat leafy greens, beans, and whole grains (folate sources)
- Include animal products (B12 source) or supplement if vegan
- Get enough B6 (chickpeas, fish, potatoes)
- Reduce coffee and alcohol (both elevate homocysteine)
- Manage stress and sleep
10. Omega-3 Index
What it measures: The percentage of omega-3 fatty acids (EPA and DHA) in your red blood cells' cell membrane.30
Optimal range: Above 8% (below 4% is linked to the highest risk)30
Why it matters: A low Omega-3 Index is linked to a higher risk of death from coronary heart disease, and in the Framingham Offspring cohort it predicted death and cardiovascular events better than total cholesterol did.3031 Blood levels in North America are typically very low (4% or less).32
How to improve it:
- Eat fatty fish 2-3 times per week (salmon, sardines, mackerel, herring)
- Take a high-quality fish oil or algae supplement (aim for 1000-2000mg combined EPA+DHA daily)
- Reduce processed foods
- Flaxseeds and walnuts contain ALA (converts to EPA/DHA, but conversion is inefficient)
- Retest in 3-4 months to confirm supplementation is working
How to Actually Test These Biomarkers
Knowing which biomarkers matter is only half the battle. The bigger obstacle is that many of the most predictive ones never appear on a routine physical. A standard checkup typically covers a basic lipid panel, a metabolic panel, and a complete blood count. That leaves the markers with the most longevity signal off the page.
To capture the full picture, ask your physician or an independent lab for an advanced cardiovascular and metabolic workup. Layer three things onto the basics: an advanced lipid panel that adds ApoB and Lp(a), a metabolic panel that includes HbA1c and fasting insulin, and an inflammation panel anchored by hs-CRP. Round it out with homocysteine and an omega-3 index. None of these are exotic, but most are opt-in, so you usually have to request them by name. Lp(a) is worth testing at least once because it is largely genetic and rarely ordered.3334 Fasting insulin often reveals metabolic trouble years before glucose or HbA1c drift, yet it is almost never included by default.3
For the markers you can actually change, retest roughly twice a year. That cadence is frequent enough to tell whether a change in diet, training, or supplementation is working, without chasing day-to-day noise. Genetic markers like Lp(a) only need a single baseline. Above all, follow the trend, not any single reading. One elevated hs-CRP after a cold or a hard workout means little;8 a value that climbs across three consecutive draws is a real signal worth acting on. A rising baseline across several tests is exactly the pattern that matters, and it only becomes visible when you measure the same markers the same way, again and again.
Making Sense of Your Biomarkers
Numbers are only useful if they tell a story. One high marker means something. The same marker in the context of five others means something different. Elevated inflammation with high glucose and low vitamin D tells a different story than inflammation from a recent infection.
This is where biomarker tracking over time becomes powerful. Merios combines blood test biomarkers with wearable data—your sleep, activity, heart rate, and stress—to reveal how your daily choices impact your molecular health. You see not just what your biomarkers are, but why they're moving in a particular direction.
Next Steps: Get Your Biomarkers Tested
If you haven't had comprehensive blood work done, now's the time. Request a lipid panel, metabolic panel, inflammation markers, thyroid panel, sex hormones, DHEA-S, homocysteine, and vitamin D. Most of these aren't standard on routine checkups, so you may need to ask specifically or work with a functional medicine practitioner.
For guidance on interpreting your results, see how to read your blood test results.
Once you have your baseline, the real work begins: the discipline of tracking, the patience of improving, and the science of understanding what actually works for your body.
The Merios Approach
This is exactly what Merios was built for. Rather than staring at a PDF lab report trying to decipher what your numbers mean, you input your results into the app. Merios contextualizes each biomarker against optimal ranges, tracks changes over time, and shows you how your lifestyle habits—captured by wearable data—correlate with your biomarkers.
Want to see what happens to your inflammation when you sleep 8 hours? Your glucose levels when you exercise? Your testosterone when you strength train consistently? Merios reveals these connections.
Learn more about Merios and explore our science-backed approach to health tracking.
Medical Disclaimer
This article is for educational purposes only and should not be construed as medical advice. Biomarker ranges and interpretation vary by individual, age, sex, and clinical context. Optimal ranges differ between health guidelines and practitioners. Always consult with a qualified healthcare provider before making health decisions based on biomarker data. Individual results may vary, and this information is not a substitute for professional medical diagnosis or treatment.
Ready to take control of your health data? Merios tracks these markers the way they should be tracked — in context, over time, next to your wearable data. Free to download on the US App Store for iPhone; Merios Plus is $44/year with a 7-day free trial on the annual plan.