Cholesterol Is Hitting New Lows for Americans
Americans are winning the cholesterol war, according to a major yardstick of the nation’s health.
Data collected by the National Health and Nutrition Examination Surveys (NHANES) showed to a significant average decline in total serum cholesterol and in low-density lipoprotein (LDL) cholesterol from 1988-1994 to 1999-2002. These findings were revealed in a report in the Oct. 12 issue of the Journal of the American Medical Association.
Driven by significant and substantial declines in total and LDL cholesterol levels in men 60 or older and women 50 or older, the total cholesterol levels fell from 206 mg/dL to 203 mg/dL (P=0.009). The LDL levels declined from 129 mg/dL to 123 mg/dL (P<0.001).
But the downward trend was not seen in younger adults and there were no significant changes in mean high-density lipoprotein (HDL) cholesterol levels, wrote Margaret D. Carroll, M.S.P.H., and colleagues of the National Center for Health Statistics here, the National Heart Lung and Blood Institute in Bethesda, and the University of Texas Southwestern Medical Center in Dallas.
High-density lipoprotein (HDL) cholesterol
The HDL cholesterol is a test that measures the amount of high-density lipoprotein (HDL) cholesterol in serum.
How the test is performed
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
More information: HDL cholesterol
Triglyceride levels in adults age 20 or older increased from an average of 118 mg/dL in 1988-1994 to 123 mg/dL in 1999-2002, but this was not significant.
In 1988-1994 20% of adult Americans had total cholesterol levels of 240 mg/dL or more but by 1999-2002 only 17% of adults had total cholesterol levels in that range.
NHANES measured serum lipids in samples from 6,098 to 15,719 adults who participated in NHANES surveys conducted 1960-1962, 1971-1974, 1976-1980, 1988-1994, and 1999-2002.
This is a test that measures the amount of low-density lipoprotein (LDL) cholesterol in serum.
Cholesterol levels are determined through chemical analysis of a blood sample taken from a finger prick or from a vein in the arm. Home cholesterol kits, first approved in 1993, test only for total cholesterol levels but are as accurate as tests done in a doctor’s office, says Steven Gutman, M.D., director of FDA’s division of clinical laboratory devices.
More information: LDL cholesterol
In NHANES, a wide battery of health-related data, including serum lipids, are collected from a representative sample of Americans in standardized examinations.
The authors attributed the lipid declines to the use of cholesterol-lowering medications by men and women in older age groups. Physicians are, the investigators wrote, prescribing more statins for more patients as a response to a number of trials conducted during the last decade that have reported significant benefits for statin therapy.
Why Low density lipoprotein is performed
This test is usually performed as part of an evaluation of coronary risk factors.
Cholesterol is an important normal constituent of the body. It is part of the structure of cell membranes, bile acids, and steroid hormones. Since cholesterol is water insoluble, most cholesterol is carried in the blood by lipoproteins (large protein-like molecules, including chylomicrons, VLDL, LDL, and HDL). Chylomicrons are lipoproteins that are present shortly after a meal, but disappear within about 2 hours in “normal” people.
The main function of LDL seems to be to carry cholesterol to various tissues throughout the body. The laboratory actually measures the cholesterol portion of the LDL molecule, rather than the actual concentration of LDL in the blood. This is also true for high density lipoprotein (HDL) and very low density lipoprotein (VLDL). The total cholesterol level is the sum of LDL, HDL, and VLDL cholesterol.
Excess cholesterol in the blood has been correlated with cardiovascular disease. LDL is sometimes referred to as “bad” cholesterol because elevated levels of LDL correlate most directly with coronary heart disease.
According to the National Heart, Lung, and Blood Institute, your LDL cholesterol level is a better indicator of your risk for a heart attack and stroke than total cholesterol. The lower your LDL, the lower your risk for heart disease or stroke.
The authors suggested that the overall cholesterol decline is likely to pay off in the future because clinical trial results suggest that a 1% decrease in LDL cholesterol translates into a 1% decrease in risk for Coronary heart disease.
Indeed, an aggressive approach to lipid-lowering is paying off, according to a paper in the Journal of the American College of Cardiology.
Stephen D. Wiviott, M.D., of the Brigham and Women’s Hospital in Boston and co-investigators from the Pravastatin or Atorvastatin Evaluation and Infection Therapy - Thrombolysis in Myocardial Infarction 22 (PROVE IT TIMI 22) suggested in a PROVE IT sub-study that even very low LDL levels are safe and beneficial for patients with cardiovascular disease.
In that study patients randomized to high dose Lipitor (atorvastatin) achieved LDL levels of less than 90 mg/dL and some patients achieved LDL levels of less than 40 mg/dL. There was no adverse effect on safety with the lower LDL levels, and apparent improved clinical efficacy.
Compared with patients who reached accepted LDL goals of 80 to 100 mg/dL, patients who achieved LDL levels in the lowest range (40 mg/dL and below) had fewer strokes, Myocardial Infarctions, and recurrent ischemia. There were also fewer heart-related deaths in this group and less need for revascularization.
Source: Journal of the American Medical Association
Revision date: June 18, 2011
Last revised: by David A. Scott, M.D.