The low-grade fire that drives aging from the inside

The Fire Within

Inflammation has two faces.

Acute inflammation is protective. When you cut your finger or catch a virus, your immune system mounts an inflammatory response: redness, swelling, heat, the marshaling of white blood cells to fight infection and repair damage. This is good. It's how your body heals.

Chronic low-grade inflammation is different. It's not a response to injury or infection. It's a smoldering, persistent activation of inflammatory pathways that damages tissue over time. It's been linked to heart disease, cancer, diabetes, Alzheimer's, and most other age-related conditions.

In 2000, researcher Claudio Franceschi coined a term for this age-related chronic inflammation: inflammaging. As Dr. Franceschi, professor emeritus at the University of Bologna and a pioneering figure in aging biology, has explained, "Inflammaging represents a highly significant risk factor for both morbidity and mortality in elderly people, as most age-related diseases share an inflammatory pathogenesis." It's now recognized as one of the central features of biological aging, connecting to nearly every hallmark of aging we've discussed.

Understanding inflammation is understanding one of the primary drivers of why and how we age.

What Inflammaging Actually Is

Inflammaging refers to chronic, sterile, low-grade inflammation that develops during aging. "Sterile" because it's not a response to infection. "Low-grade" because it's subtle, not the obvious inflammation of a wound or illness.

Research defines it as elevated blood levels of inflammatory markers without acute illness. Someone with inflammaging won't feel inflamed in the way they'd feel a swollen ankle. It's subclinical, detectable only through laboratory tests.

But the effects accumulate over decades.

Why It Happens

Several interconnected processes drive inflammaging:

Cellular senescence. As we age, more cells enter a state called senescence, where they stop dividing but don't die. These zombie cells secrete inflammatory factors called the SASP (senescence-associated secretory phenotype). Even when senescent cells comprise only 2-3% of tissue, they produce enough SASP to significantly increase local and systemic inflammation.

Immune system changes. The immune system becomes simultaneously less effective at fighting pathogens (immunosenescence) and more prone to inflammatory activation. This paradox, being weaker yet more inflamed, is characteristic of aging.

Damaged mitochondria. Dysfunctional mitochondria release signals that activate inflammatory pathways. As mitochondrial dysfunction increases with age, so does this source of inflammation.

Gut changes. Increased intestinal permeability ("leaky gut") allows bacterial products to enter the bloodstream, triggering immune responses. Gut microbiome changes with age also affect inflammatory tone.

Chronic infections. Persistent viral infections, like cytomegalovirus (CMV), which most adults carry, can keep the immune system in a state of chronic activation.

Metabolic dysfunction. Excess body fat, particularly visceral fat, is metabolically active and produces inflammatory cytokines. Metabolic syndrome is both a cause and consequence of inflammation.

The Evidence: Inflammation Predicts Bad Outcomes

The link between inflammaging and disease isn't theoretical. It's demonstrated repeatedly in large population studies.

Mortality Risk

Studies consistently find that higher levels of inflammatory markers predict mortality. As Dr. Luigi Ferrucci, scientific director at the National Institute on Aging and a leading researcher in inflammaging, has stated, "Chronic inflammation is not just a marker of aging but an active driver of the aging process itself, directly contributing to functional decline and disease." Research from the Cardiovascular Health Study found that elevated IL-6 (interleukin-6) and CRP (C-reactive protein) were associated with more than double the risk of death in elderly individuals.

A Polish study of elderly participants found that high levels of IL-6 and CRP were significantly associated with increased mortality risk, with hazard ratios of 2.18 and 2.58 respectively.

Importantly, these associations held after controlling for other factors like age, cardiovascular disease, diabetes, and functional status. Inflammation predicts mortality independently.

Disease Connections

Inflammaging is a risk factor for:

Cardiovascular disease: Chronic inflammation promotes atherosclerosis, plaque formation, and cardiovascular events.
Type 2 diabetes: Inflammation impairs insulin signaling and contributes to insulin resistance.
Cancer: Chronic inflammation creates an environment that supports tumor development and progression.
Dementia: Neuroinflammation contributes to neurodegeneration and is implicated in Alzheimer's disease.
Sarcopenia: Inflammation promotes muscle breakdown and inhibits muscle protein synthesis.
Frailty: Elevated inflammatory markers predict physical decline and loss of independence.
Depression: Inflammation affects brain function and mood regulation.

The relationship often goes both ways. Chronic diseases cause inflammation, and inflammation accelerates disease progression. This creates a negative spiral where aging, inflammation, and disease reinforce each other.

The Senescent Cell Connection

One of the most important sources of inflammaging is cellular senescence. Understanding this connection helps explain why inflammation increases with age.

When cells become damaged beyond repair (by DNA damage, oxidative stress, or other insults), they can either die (apoptosis) or enter senescence. Senescent cells permanently exit the cell cycle, meaning they can no longer divide.

This seems protective. Stopping damaged cells from dividing prevents cancer. And indeed, cellular senescence is a tumor suppression mechanism.

But there's a dark side.

The SASP Problem

Senescent cells don't just sit quietly. They actively secrete a cocktail of inflammatory molecules, growth factors, and tissue-degrading enzymes collectively called the senescence-associated secretory phenotype (SASP).

The SASP includes:

IL-6 and IL-8: Core inflammatory cytokines
TNF-alpha: Another key inflammatory mediator
Matrix metalloproteinases: Enzymes that break down structural tissue
Growth factors: That can promote cancer in nearby cells

This secretion isn't brief. Senescent cells persist and continue producing SASP for years or decades.

The Cascade Effect

The SASP can induce senescence in neighboring healthy cells, creating a spreading wave of dysfunction. Research shows that the inflammatory factors secreted by senescent cells can trigger senescence in surrounding tissue, expanding the problem beyond the original damaged cells.

With age, senescent cells accumulate. By some estimates, they can comprise a meaningful percentage of cells in various tissues by later life. Even at low percentages, their inflammatory output significantly elevates systemic inflammation.

This is why targeting senescent cells (with drugs called senolytics) has become an active area of longevity research. If you can clear senescent cells, you may be able to reduce inflammaging at its source.

Measuring Your Inflammatory Status

Several blood tests can assess inflammatory burden:

C-Reactive Protein (hs-CRP)

The most commonly used clinical marker. CRP is produced by the liver in response to inflammation. The high-sensitivity version (hs-CRP) can detect low-grade chronic inflammation. As Dr. Paul Ridker, director of the Center for Cardiovascular Disease Prevention at Brigham and Women's Hospital and lead investigator of the landmark CANTOS trial, has noted, "CRP is not just a marker of inflammation but represents a therapeutic target, as demonstrated by our trial showing that reducing inflammation reduces cardiovascular events."

What to aim for: Below 1.0 mg/L is optimal. Above 3.0 mg/L is associated with significantly increased cardiovascular and mortality risk based on current evidence as of 2026.

Caveats: CRP is non-specific. It can be elevated from acute infection, injury, or many other causes. Single readings aren't definitive. Patterns over time are more meaningful.

IL-6 (Interleukin-6)

IL-6 is an "upstream" inflammatory marker. It triggers CRP production and is often elevated before CRP rises. Some researchers consider it a more sensitive indicator.

Availability: Less commonly ordered than CRP, but available through most labs.

Other Markers

Fibrinogen: A clotting factor that increases with inflammation
ESR (erythrocyte sedimentation rate): A general inflammation marker
Homocysteine: Elevated levels associated with vascular inflammation

For more on testing and optimal ranges, see our biomarkers guide.

What Drives Inflammation Up

Understanding what elevates inflammation points toward what you can change.

What Increases Inflammation

Excess body fat, particularly visceral fat (belly fat). Fat tissue produces inflammatory cytokines. The more visceral fat, the higher the inflammatory burden.

Sedentary lifestyle. Lack of physical activity is associated with higher inflammatory markers.

Poor sleep. Chronic sleep deprivation elevates inflammatory markers. Sleep disorders like apnea are particularly inflammatory.

Chronic stress. Sustained psychological stress activates inflammatory pathways through cortisol and other mechanisms.

Smoking. Directly inflammatory. Smoking cessation reduces inflammation relatively quickly.

Excessive alcohol. Moderate alcohol may be neutral or slightly beneficial; excessive intake is inflammatory.

Ultra-processed diet. High intake of processed foods, added sugars, trans fats, and refined carbohydrates promotes inflammation.

Gut dysfunction. Increased intestinal permeability allows bacterial products to trigger immune responses.

Chronic infections. Periodontal disease, chronic viral infections, and other persistent infections maintain inflammatory activation.

Environmental factors. Air pollution, toxic exposures, and other environmental insults can drive chronic inflammation.

What Brings Inflammation Down

The encouraging news: inflammation is modifiable. Many lifestyle factors have demonstrated anti-inflammatory effects.

Diet

The evidence for anti-inflammatory diets is strong. Harvard researchers note that the evidence is strongest for arthritis, gastrointestinal health, heart health, and autoimmune conditions.

Anti-inflammatory foods:

Fatty fish (omega-3s reduce IL-6 and CRP)
Olive oil (oleocanthal has anti-inflammatory properties)
Leafy greens and colorful vegetables
Berries and other antioxidant-rich fruits
Nuts, especially walnuts
Whole grains
Legumes

Pro-inflammatory foods to minimize:

Ultra-processed foods
Added sugars
Trans fats (largely eliminated but still in some foods)
Excessive refined carbohydrates
Processed meats

The Mediterranean diet consistently shows anti-inflammatory effects and is associated with lower CRP and other inflammatory markers.

Exercise

Regular physical activity is one of the most reliable ways to reduce inflammation. Research shows that exercise lowers CRP levels independent of weight loss.

The paradox: acute exercise temporarily increases inflammation (which signals adaptation), but chronic regular exercise reduces baseline inflammation. This is the same pattern we see with exercise and longevity more broadly.

Both aerobic exercise and resistance training have anti-inflammatory effects. Consistency matters more than intensity.

Sleep

Adequate sleep (7-8 hours for most adults) reduces inflammatory markers. Sleep deprivation has the opposite effect.

Addressing sleep disorders like sleep apnea is particularly important, as these conditions substantially elevate inflammation.

See our sleep and aging article for more.

Stress Management

Chronic psychological stress elevates inflammatory markers. Interventions that reduce stress, including meditation, social support, and addressing underlying causes, can reduce inflammation.

See our stress, mindset, and longevity article.

Weight Management

Losing excess body fat, particularly visceral fat, significantly reduces inflammatory markers. This is one mechanism by which weight loss improves metabolic health.

Even modest weight loss (5-10%) can produce meaningful reductions in CRP and other inflammatory markers.

Not Smoking

Smoking is directly inflammatory. Cessation reduces inflammatory markers within weeks to months.

The Integrated View

Inflammation doesn't exist in isolation. It's both cause and consequence of other aging processes.

Inflammation drives:

Oxidative stress (and oxidative stress increases inflammation)
Insulin resistance (and metabolic dysfunction increases inflammation)
Cellular senescence (and senescent cells produce inflammation)
Tissue damage (and tissue damage triggers inflammation)

This interconnection is why lifestyle interventions that affect multiple pathways are so effective. Exercise reduces inflammation while also improving metabolic health, reducing oxidative stress, and promoting autophagy. Good nutrition reduces inflammation while also supporting metabolic health and reducing the substrate for oxidative damage.

You can't fully separate these processes. That's actually good news: interventions that work on one system tend to help across multiple systems.

Practical Takeaways

Inflammaging is real, measurable, and modifiable. Here's what to do with that knowledge:

Monitor (Periodically)

Get hs-CRP tested annually or every few years. It's part of understanding your baseline and tracking whether your interventions are working.

Don't panic about a single elevated reading. Look for patterns over time. If CRP is consistently elevated without obvious acute cause, it warrants attention.

Address the Fundamentals

The same lifestyle factors that support longevity reduce inflammation:

Regular physical activity (both aerobic and resistance training)
Adequate sleep (7-8 hours, address sleep disorders)
Healthy body weight (especially reducing visceral fat)
Anti-inflammatory diet (Mediterranean pattern or similar)
Stress management
Not smoking, moderate alcohol

These aren't separate interventions. They're reinforcing components of an integrated approach to healthy aging.

Consider What's Elevated

If inflammation markers are high despite good lifestyle habits, consider:

Undiagnosed sleep apnea
Hidden infections (dental, chronic viral)
Autoimmune conditions
Gut issues
Environmental exposures

Work with your healthcare provider to identify potential sources.

Think Long-Term

Inflammaging develops over decades. The interventions that address it work best when sustained over time. Short-term dramatic changes followed by returning to old patterns won't provide lasting benefit.

The goal isn't perfection. It's sustained reasonable habits that keep inflammatory burden low over years and decades.

The Bottom Line

Chronic low-grade inflammation, inflammaging, is one of the central features of biological aging. It's driven by senescent cells, immune dysfunction, metabolic problems, and lifestyle factors. It predicts mortality and age-related disease independently of other risk factors.

But it's modifiable.

The same lifestyle interventions that extend healthspan, regular exercise, adequate sleep, healthy nutrition, stress management, healthy body weight, all reduce inflammatory burden. You don't need special anti-inflammatory protocols. You need sustained attention to the fundamentals.

Inflammation connects exercise, sleep, nutrition, stress, and body composition to aging and disease. It's why these lifestyle factors matter, and it's one of the primary mechanisms through which they work.

The fire is burning. But you have significant control over how hot it gets.

Sources

Franceschi, C., et al. (2018). "Inflammaging: a new immune-metabolic viewpoint for age-related diseases." Nature Reviews Endocrinology. Link
Franceschi, C. & Campisi, J. (2014). "Chronic inflammation (inflammaging) and its potential contribution to age-associated diseases." Journals of Gerontology. Link
Ferrucci, L. & Fabbri, E. (2018). "Inflammageing: chronic inflammation in ageing, cardiovascular disease, and frailty." Nature Reviews Cardiology. Link
Coppe, J.P., et al. (2010). "The senescence-associated secretory phenotype: the dark side of tumor suppression." Annual Review of Pathology. Link
Tchkonia, T., et al. (2013). "Cellular senescence and the senescent secretory phenotype: therapeutic opportunities." Journal of Clinical Investigation. Link
Ferrucci, L., et al. (2005). "Serum IL-6 level and the development of disability in older persons." Journal of the American Geriatrics Society.
Ridker, P.M., et al. (2017). "Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease." New England Journal of Medicine.
Harvard Health. "Foods that fight inflammation." Link

Inflammation & Aging: The Fire Within

Key Findings:

Important Limitations: