IThe immune system gets compromised by bacteria and viruses , vitamin deficiency and poor diet causing autoimmune disease.

In a medical version of the “unified field” theory in physics, many scientists now believe that most—or perhaps all—chronic diseases may have the same trigger: inflammation. This fiery process has been linked to everything from heart attacks and strokes to type 2 diabetes, Alzheimer’s disease, and even cancer.

Chronic, low-grade systemic inflammation—fueled by such disorders as excessive belly fat, poor diet, lack of exercise, smoking, and gum disease—may explain why lifestyle-linked diseases have reached epidemic levels in Western countries, while remaining rare in the developing world.

“There are clear indications that inflammation explains why plaque builds up in the arteries in patients with atherosclerosis,” says Philip Schauer, MD, director of the Bariatric and Metabolic Institute at the Cleveland Clinic. “Chronic inflammation also plays a direct role in diabetes, high blood pressure, sleep apnea, asthma and many other conditions.”

The Missing Puzzle Piece

Two groundbreaking new studies published in Lancet suggest that fire inside the artery walls could be the missing puzzle piece to solve the mystery of why many people with normal or even optimal cholesterol levels suffer heart attacks or strokes, while others with very high cholesterol never develop heart disease.

The studies were the first to show a cause-and-effect relationship between a specific inflammatory marker (interleukin 6, also known as IL-6) and heart disease risk—a discovery that could lead to revolutionary new therapies to treat or prevent the leading killer of Americans.

The researchers pooled data from nearly 135,000 people and found that those with a gene variant linked to a lower-than-normal number of IL-6 receptors were much less likely to develop heart disease, even though they had the same rates of smoking, diabetes, high cholesterol, and other risk factors as people without this variant.

The findings suggest that medication to block IL-6 receptors—currently used to treat rheumatoid arthritis (also an inflammatory disease)—could be a new weapon against heart disease.

Is Your Body on Fire?

Most of the time, inflammation protects health. If you stepped on a nail, your body would mobilize immune system troops to battle the invading bacteria by releasing signaling molecules, such as IL-6, to launch the inflammatory cascade. The immune system reaction involves more than 20 proteins that blast the invaders with chemicals to kill them, along with an assortment of odd-looking white blood cell components that resemble characters from Creepshow2.

The result of this immune system response is the familiar feeling of redness and warmth around the wound as it starts to heal. Chronic inflammation, however, harms rather than heals, because the immune system attack never stops. It’s like being shot by “friendly fire” during a perpetual war raging inside the body, says Dr. Schauer.

The #1 Warning Sign of Chronic Inflammation

The easiest way to tell if your body—and arteries—might be on fire is to measure your waist. A circumference above 35 inches for a woman or 40 inches for a man means you could be at risk for a variety of dangerous diseases linked to chronic inflammation, even if your weight is normal.

“Excessive visceral fat is very different than fat in other parts of the body,” says Dr. Schauer. “Abdominal fat cells are much more biologically active than subcutaneous fat cells, releasing several hormones and cytokines [chemical messengers involved in immune system and inflammatory responses]. There is also a genetic component to both chronic inflammation and obesity—it’s not just an unhealthy lifestyle that leads to these problems.”

A big belly is also the leading indicator of metabolic syndrome, a gang of five metabolic thugs that quintuple risk for type 2 diabetes and triple it for heart attack. Fifty million Americans, many of whom are undiagnosed, suffer from this dangerous disorder.

If you have three or more of the following disorders, you have metabolic syndrome:

A large waistline. This also is called "an apple shape."
High triglycerides: a level of this blood fat above 150 mg/dL
Low HDL (less than 50 mg/dL for women and less than 40 mg/dL for men). HDL is the good cholesterol that keeps the heart and brain healthy.
High blood pressure: 130/85 mmHg or higher (or you’re on blood pressure medicine).
High fasting blood sugar: 100 mg/dL or above (or you're on medicine to treat high blood sugar).