Cholesterol continues 30-year decline.

The war on heart disease continues, but there's good news from the cholesterol front: The latest federal survey of U.S. health and nutrition reveals a significant and continuing decline in the amount o! artery-clogging cholesterol flowing through America's collective bloodstream.

This decline in blood cholesterol, which can block the arteries that supply the heart with blood, may ultimately reduce individuals' risk of coronary artery disease in the United States by as much as 32 percent, according to Manning Feinleib, director of the National Center for Health Statistics (NCHS) in Hyattsville, Md.

Also this week, the National Cholesterol Education Program (NCEP), coordinated by the National Heart, Lung, and Blood Institute in Bethesda, Md., has released new guidelines for the diagnosis and treatment of high cholesterol.

Two studies based on the recent survey and the revised NCEP guidelines appear in the June 16 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION.

According to NCHS researchers, virtually all of the decline in blood cholesterol - 8 percent since 1960 -was in low-density lipoprotein (LDL), the carrier molecule that deposits cholesterol on artery walls, leading to heart disease (SN: 9/9/89, p. 171). In contrast, highdensity lipoprotein (HDL), which ferries cholesterol to the liver for disposal, rose only 1 percent in the same period. More than half of the LDL decrease occurred in the period from 1976 to 1991 coinciding roughly with increased public-education programs to convince Americans to reduce their intake of dietary fats. Indeed, since 1978, cholesterol counts have fallen, on average, from 213 milligrams of cholesterol per deciliter of blood to 205. According to NCEP guidelines, a cholesterol count of 200 or less in a normal adult is considered "desirable."

The NCHS studies are based on data from four national surveys that gathered health and nutrition information on thousands of Americans. The most recent National Health and Nutrition Examination Survey (NHANES III) covered the period 1988 to 1991 and involved 8,000 men and women. Participants were black, white, or Mexican American.

The new NCEP treatment guidelines, building on a previous incarnation published in 1988, reaffirm some classic themes in anticholesterol therapy and reflect the most current scientific data NCEP officials explained at a June 15 press briefing in Washington, D.C. For example, the new guidelines stilt mark LDL as the primary target of cholesterol-lowering therapy, but they urge physicians to determine the amount of HDL cholesterol in patients' blood, even labeling it a "negative risk factor" for heart disease. In other words, increasing HDL can reduce a person's risk of developing blocked coronary arteries and the debilitating heart attacks that may follow.