The Hidden Health Killer—Occult (Subclinical) Inflammation
Inflammation is the basic pathological process, predominantly defensive, that occurs in vascularized living tissue under the stimulus of various injurious factors. A typical inflammatory response includes local and systemic manifestations: the local signs are redness, swelling, heat, pain, and dysfunction; the systemic reactions include fever, changes in peripheral blood white-cell count, tachycardia, elevated blood pressure, chills, and anorexia. Inflammation can be classified in various ways: by duration it is hyperacute, acute, subacute, or chronic; by organ involved it is myocarditis, hepatitis, gastritis, nephritis, and so on; by severity it is mild, moderate, or severe.
Most inflammations produce clinical symptoms and can be detected. But one kind is easily missed: occult inflammation, also called sub-inflammation or para-inflammation. It is a mild, chronic, asymptomatic systemic inflammation that lies between tissue homeostasis and classic inflammation, arising under conditions of tissue stress and functional abnormality.
Early sub-inflammation is an adaptive response that benefits the body and matters greatly for maintaining homeostasis. But inflammation that fails to resolve over the long term develops into dysregulated occult inflammation, becoming a chronic non-resolving inflammation. This kind contributes to serious diseases such as metabolic syndrome, diabetes, cardiovascular and cerebrovascular disease, polycystic ovary syndrome, cancer, Alzheimer's disease, and chronic kidney disease.
Strictly speaking, occult inflammation is not without warning signs; its symptoms are simply easy to overlook. It manifests as easy fatigue, minor skin problems, or digestive abnormalities, but most patients dismiss these as trivial "sub-health," mistaking them for ordinary tiredness that rest will fix.
Occult inflammation is also the disease most easily missed or misdiagnosed by doctors; many doctors themselves are in a state of occult inflammation without knowing it. Patients with long-standing occult inflammation keep releasing inflammatory factors such as C-reactive protein and IL-6; these can cause tissue damage, disrupt the vascular intima, and raise the risk of atherosclerosis and cellular malignant transformation.
Main triggers of occult inflammation include poor diet (high sugar, high trans fat, high protein, and heavily processed foods), obesity, excessive stress, sleep deprivation, air pollution, long-term chemical exposure, and chronic infection (such as Helicobacter pylori or hepatitis B virus). These triggers are closely relevant to nearly every one of us.
Occult inflammation is not as treatable as typical inflammation; we cannot simply use drugs to treat it. Improving lifestyle and dietary habits has excellent preventive and therapeutic effects. We can prevent and treat it by increasing anti-inflammatory foods (such as dark-colored vegetables, omega-3-rich fish, nuts, and berries), reducing high-sugar, high-fat, high-protein intake, quitting smoking and limiting alcohol, exercising regularly, managing weight, supplementing essential vitamins, improving sleep, and better managing stress.
Some oncologists liken cancer to an inflammation that never heals, and this makes good sense. Many tumors develop from occult inflammation; occult inflammation can be regarded as a precancerous lesion for some cancers. If, before a tumor arises, we take a series of measures to improve occult inflammation, we can prevent many cancers.