Oct. 16, 2012 -- Cholesterol levels are dropping among U.S. adults, new research shows.
From 1988 to 2010, average levels of total cholesterol, LDL, and blood fats called triglycerides fell for all groups of U.S. adults. Levels of HDL ("good") cholesterol started to rise during this time frame.
"We show that one risk factor may be decreasing and we will have to see what happens," Carroll says. "Hopefully, progress will be made with the other risk factors as well."
Carroll's study doesn't show why cholesterol levels dropped. The change may be due, at least in part, to the growing numbers of U.S. adults who take cholesterol-lowering medications such as statins.
From 1988 to 1994, 3.4% of adults took a statin. This percentage jumped to 15.5% in 2007-2010.
"Statins dramatically reduce LDL levels and reduce risk of heart attack and stroke, and people live longer," says cardiologist Holly Andersen, MD, director of education and outreach for the Perelman Heart Institute at New York-Presbyterian Hospital/Weill Cornell Medical Center.
Yet, a drop in cholesterol levels was also seen in adults not taking statins or other drugs to lower cholesterol. This suggests there may be other things going on, such as efforts to remove trans fats from our diets.
According to the new study:
According to the American Heart Association, total cholesterol should be less than 200 mg/dL of blood, and optimal LDL should be less than 100 mg/dL. Triglycerides, too, should be less than 100 mg/dL, and HDL should be 60 mg/dL or above for optimal heart health.
These positive cholesterol trends have already started to make a dent in rates of heart disease, says Steven Nissen, MD. He is the chair of cardiovascular medicine at the Cleveland Clinic in Ohio.
"We know that the single best predictor of heart disease is cholesterol levels, and they have been going down," Nissen says.
"Levels of LDL cholesterol have declined substantially, and along with that decline, we are seeing a reduction in age-related heart disease," he says. Rates of heart disease have declined steadily since the 1960s, according to the CDC.
"This is a good news story, but there are storm clouds on the horizon," Nissen says. Soaring rates of obesity and diabetes threaten to overshadow this progress.
"The most likely and plausible explanation is that the decline in cholesterol is due to the more extensive use of medication in the at-risk population," he says. "We are not moving more or getting lighter, and this didn't happen by accident."
The new study serves to back up some of these points. There was not a decrease in how much cholesterol-raising saturated fat U.S. adults ate as a percentage of their daily calories, and there was little progress made in boosting physical activity among adults.
The health message is clear and applies to all adults. "Know your LDL," he says. "If it is above the optimal level, ask your doctor if you have a high enough risk to warrant treatment."