Safe levels of total cholesterol fall anywhere beneath 200 milligrams per deciliter of blood, according to the American Heart Association. Total cholesterol is the sum of LDL and HDL cholesterol. LDL should be lower than 100 milligrams per deciliter, while HDL should be above 60 milligrams per deciliter.
When cholesterol goes beyond these limits, the risk of heart attack, stroke and heart disease climbs significantly. When LDL cholesterol levels are too high, some of it builds up on the walls of the arteries, eventually forming plaque that makes the arteries stiff and narrow. Clots that block one of these arteries often lead to stroke or heart attack, notes the American Heart Association.