Atherosclerotic plaques cause narrowing of the arteries, and lead to heart attacks and strokes. Much evidence has now accumulated that increased HDL cholesterol levels are associated with a lower risk of heart disease, and that low HDL cholesterol levels are associated with an increased risk of heart disease. Thus, HDL cholesterol appears to be good. There is some evidence that the HDL molecule scours the walls of blood vessels, and cleans out excess cholesterol. Apparently, unlike some bad humans, bad cholesterol can be rehabilitated.
Triglycerides get little respect.
Their measurement is part of a standard blood lipid profile, but for the most part doctors don t know what to do when triglyceride levels are modestly elevated. While high triglyceride levels have been associated with heart disease, no study has yet proven that high triglyceride levels are an independent risk factor for heart disease. So doctors don t have the evidence they need to recommend aggressive triglyceride-lowering therapy. It turns out that whenever triglycerides are increased, HDL cholesterol decreases. So far, nobody can say for sure.