HDL: Good and brainy
The "good" cholesterol particle may help fend off strokes and dementia in addition to preventing heart disease, so it's time to pay it some mind.
High-density lipoprotein (HDL) is the "good" cholesterol particle. Under the right conditions, HDL scoops up cholesterol from macrophages that have infiltrated artery walls and deposits it in the liver, which then excretes the scavenged cholesterol harmlessly into the small intestine as bile salts. And HDL's benefits may go well beyond cholesterol removal. Studies suggest that it may retard inflammation, inhibit the formation of blood clots, and prevent oxidation of lipids, a central event in the artery-damaging atherosclerotic process. If HDL does all that, calling it the "good" cholesterol hardly seems adequate.
The main consequence of having high HDL levels is a lower risk of heart disease. A small but growing number of studies suggest that high levels might also ameliorate stroke and dementia risks. Late in 2007, for example, a re-analysis of data from the Vitamin Intervention for Stroke Prevention study showed that people with high HDL levels were more likely to fully recover from a mild or moderate stroke. Other studies have found that high HDL lowers people's chances of having certain kinds of strokes. And there's some interest in experimenting with HDL levels to treat strokes.