C-reactive protein (CRP)
The liver produces CRP when inflammation occurs anywhere in the body—including in the walls of the arteries. People with even small elevations of CRP have an increased risk of heart attacks regardless of their age, gender, general health, or other risk factors. In fact, elevated CRP levels (more than 2 to 3 mg/L) are found in up to half of all people who have a heart attack.
The combination of an elevated LDL cholesterol level and a high CRP level increases the chances of a heart attack several-fold. One study of nearly 4,000 adults with stable coronary heart disease found that those with CRP levels of more than 3 mg/L were 52 percent more likely than those with CRP readings of less than 1 mg/L to suffer a heart attack or stroke or die of cardiovascular disease over a five-year period.
Physical activity, weight loss, quitting smoking, and statins all help to reduce levels of CRP. In one study, individuals who had a heart attack were less likely to have another one if their CRP levels were lowered while taking a statin. Researchers have yet to prove that lowering CRP prevents a first heart attack. What’s more, other heart attack risk factors such as elevated blood glucose and triglyceride levels and increased abdominal fat are associated with an elevated CRP.
High blood levels of homocysteine are associated with an increased risk of heart attacks, strokes, and peripheral arterial disease. In one study, individuals with the highest homocysteine levels had about a threefold greater risk of a heart attack than those with lower levels. Doctors are uncertain how homocysteine affects the arteries, but high levels may promote atherosclerosis by damaging the cells that line the artery walls and promoting the buildup of plaques. Homocysteine may also stimulate blood clotting.
Levels of homocysteine can be reduced with folic acid supplements, but several large studies show that these supplements do not reduce heart attack risk.