Inflammation is your immune system’s response to anything it perceives as a threat, whether that’s a splinter, a bacterial infection, or ongoing damage from something like excess blood sugar. In small doses, it heals you. But when the triggers don’t go away, inflammation becomes chronic and starts contributing to heart disease, diabetes, joint damage, and other long-term conditions. Understanding what kicks off this process, and what keeps it going, is the first step toward bringing it under control.
Acute vs. Chronic: Two Different Problems
When you cut your finger or catch a cold, your body launches acute inflammation. White blood cells rush to the site, blood vessels widen to let them through, and the area swells, reddens, and heats up. This process resolves in hours to days. It’s effective, temporary, and necessary for survival.
Chronic inflammation is a different beast entirely. Instead of the fast-acting immune cells that handle acute threats, chronic inflammation involves slower, longer-lived immune cells: lymphocytes, macrophages, and plasma cells that settle into tissues and activate the cells responsible for scarring and tissue remodeling. This type of inflammation can persist for years, sometimes for life. Over-the-counter anti-inflammatory drugs like ibuprofen work well for acute flare-ups but are largely ineffective against chronic inflammation over the long run. What makes chronic inflammation especially tricky is that the exact trigger is often unclear, even to researchers. In many chronic conditions, the initial spark that set off the immune response is never definitively identified.
How Blood Sugar Spikes Fuel Inflammation
One of the most well-documented dietary triggers of inflammation is high blood sugar. When glucose levels spike, your body produces reactive oxygen species (essentially, unstable molecules that damage cells). This oxidative stress activates genes that produce inflammatory signaling proteins called cytokines, including TNF-alpha and interleukin-6. In lab studies, immune cells exposed to high glucose for 18 hours showed a dramatic increase in TNF-alpha release driven directly by this oxidative damage.
The effect isn’t just a lab phenomenon. In human studies, plasma cytokine levels rose significantly within hours of glucose spikes. People with impaired glucose tolerance (a prediabetic state) experienced higher cytokine peaks that lasted roughly twice as long as in people with normal blood sugar regulation: four hours versus two. When participants were given glutathione, a powerful antioxidant, during the same glucose challenge, cytokine levels didn’t budge from baseline. This strongly suggests that oxidative stress is the mechanism connecting sugar to inflammation.
This doesn’t mean all sugar is inflammatory. The problem is repeated, sharp spikes, the kind caused by refined carbohydrates, sugary drinks, and processed foods eaten without fiber, fat, or protein to slow absorption.
Chronic Stress and Cortisol Resistance
Cortisol, the hormone your body releases during stress, is actually one of the most potent anti-inflammatory substances your body makes. Under normal circumstances, it keeps your immune system in check. The problem arises when stress becomes chronic.
Prolonged stress changes how your immune cells respond to cortisol. Over time, the receptors on immune cells that detect cortisol become fewer in number and less sensitive. This is sometimes called glucocorticoid receptor desensitization. In practical terms, your body is still pumping out cortisol, but your immune cells stop listening to it. Without that brake pedal, inflammatory signaling goes unchecked. This is one reason why people under chronic psychological stress, whether from work, relationships, financial hardship, or trauma, show elevated markers of inflammation even when they’re otherwise healthy.
Your Gut Barrier and Bacterial Toxins
Your intestinal lining is only one cell layer thick in many places, and it relies on tight junction proteins to keep the contents of your gut from leaking into your bloodstream. When this barrier breaks down (a condition sometimes called increased intestinal permeability), bacterial toxins can slip through.
The main culprit is a molecule called lipopolysaccharide, or LPS, which sits on the outer surface of certain gut bacteria. Under normal conditions, LPS stays inside your intestines where it’s harmless. But when the gut lining is compromised, whether from poor diet, alcohol, medications, or an imbalanced microbiome, LPS enters the blood in higher concentrations. Once there, it triggers a strong immune response: high levels of inflammatory cytokines and oxidative stress throughout the body. Research in animal models has shown that when tight junction proteins like occludin and claudin are downregulated and LPS-producing bacteria increase simultaneously, the result is measurable systemic inflammation.
This is one reason gut health has become such a focus in inflammation research. The composition of your gut bacteria directly influences how much LPS is produced and how easily it can escape into circulation.
What Happens When You Don’t Move
Regular physical activity is one of the strongest natural anti-inflammatory behaviors available to you, and its absence has measurable consequences. When muscles contract during exercise, they release signaling molecules called myokines that help regulate immune function. One key effect is the production of interleukin-10, an anti-inflammatory molecule, along with the immune cells (regulatory T cells) that produce it.
Sedentary behavior suppresses this process. Research in older adults found that prolonged sitting and low muscle activity were linked to lower levels of interleukin-10 and fewer regulatory T cells. Without this counterbalance, the body’s baseline level of inflammation creeps upward. This helps explain why sedentary lifestyles are so consistently linked to conditions driven by chronic inflammation, including cardiovascular disease, type 2 diabetes, and certain cancers, even in people who aren’t overweight.
Other Common Triggers
Beyond the major categories above, several other factors reliably promote inflammation:
- Excess body fat. Fat tissue, particularly visceral fat around the organs, is metabolically active. It continuously releases inflammatory cytokines, creating a low-grade inflammatory state that persists as long as the excess fat does.
- Sleep deprivation. Even short-term sleep loss (fewer than six hours per night for a week) raises circulating inflammatory markers. Chronic poor sleep compounds this effect over time.
- Smoking and air pollution. Inhaled irritants damage lung tissue and trigger a local inflammatory response that often becomes systemic, raising inflammation throughout the body.
- Alcohol. Heavy or chronic alcohol use damages the gut lining (increasing LPS leakage) and directly stresses liver cells, both of which drive inflammatory signaling.
- Trans fats and highly processed oils. These fats promote the production of inflammatory molecules and interfere with anti-inflammatory pathways.
How Chronic Inflammation Is Measured
Chronic inflammation often produces no obvious symptoms for years. You won’t necessarily feel swollen or feverish. Instead, the damage accumulates quietly in blood vessels, joints, and organs. This is why blood tests matter.
The most widely used marker is high-sensitivity C-reactive protein (hs-CRP), a protein your liver produces in response to inflammation. Current guidelines from the American College of Cardiology flag an hs-CRP level of 2 mg/L or higher as a risk-enhancing factor for heart attack, stroke, and other cardiovascular events. This threshold is especially useful for people whose risk profile is otherwise borderline. An hs-CRP below 1 mg/L is generally considered low risk, while levels between 1 and 3 suggest moderate inflammation. Values above 3 may indicate significant systemic inflammation or an active infection.
If you’re concerned about chronic inflammation, hs-CRP is a reasonable starting point. It won’t tell you where the inflammation is coming from, but it gives you a snapshot of how much is circulating in your body right now.