Being fit protects against heart disease. Fitness improves all conventional markers of heart disease risk -- and then some. Where does the extra benefit come from? Part of it may be in reducing inflammation of blood vessels.
Inflammation starts as a protective process. Inflamed tissues swell, redden, and leak fluids. They also attract and activate cells of the immune system, which attack whatever they recognize as harmful. The process fights infection -- but causes tissue damage, too. Inflammation is a key factor leading to heart disease and stroke.
C-reactive protein is a chemical messenger that tissues give off when they get inflamed. People with heart disease have abnormally high levels of C-reactive protein -- 8.0 mg/L or higher. Does fitness have anything to do with C-reactive protein levels? Yes, finds Johns Hopkins researcher Samia Mora, MD.
In studies reported at this week's Scientific Sessions meeting of the American Heart Association, Mora measured C-reactive protein in patients with premature heart disease and in 500 of their apparently healthy siblings. She found that as C-reactive protein levels went up, fitness went down.
"Every 1 mg/L increase in C-reactive protein was equivalent to the effect [on exercise duration] of being approximately two years older," Mora writes in her presentation abstract.
However, it's not yet clear whether C-reactive protein is the cause or the effect of poor fitness.
"At this point, we're not sure if poor fitness level causes the increase in C-reactive protein or vice versa," Mora says in a news release.