Mean Serum Lipids Have Improved Since Late 1980s



Mean serum levels of lipids have improved among American adults since the late 1980s, according to an analysis of data from three nationwide surveys, published Oct. 17 in JAMA.

Between 1988 and 2012, mean total cholesterol, non-HDL cholesterol, and LDL cholesterol levels have declined and mean HDL cholesterol levels have risen in adults overall as well as across most racial/ethnic and gender categories, said Margaret D. Carroll of the Division of Health and Nutrition Examination Surveys, National Center for Health Statistics, Hyattsville, Md., and her associates.

The investigators examined data from the National Health and Nutrition Examination Surveys (NHANES) for 1988-1994, 1999-2002, and 2007-2010 to track temporal trends in lipid levels. Each cross-sectional survey included health-related interviews and physical examinations of a nationally representative sample of tens of thousands of adults.

In the adult population as a whole, the mean total cholesterol level declined in a linear fashion from 206 mg/dL in 1988-1994 to 203 mg/dL in 1999-2002 and to 196 mg/dL in 2007-2010. This pattern remained the same in separate analyses of men and women and in all racial/ethnic subgroups, except for Mexican American men (JAMA 2012;308:1545-54).

LDL cholesterol also decreased in a linear fashion in all adults, from 128 mg/dL in the first survey to 124 mg/dL in the second and to 119 mg/dL in the final survey. LDL cholesterol levels declined in both men and women and eventually converged, so there was no longer a difference between the sexes in the latest survey.

HDL cholesterol rose in a linear fashion from 50.7 mg/dL to 52.5 mg/dL among all adults, and also rose in separate analyses of both sexes. When the data were broken down by racial/ethnic categories, HDL cholesterol rose in whites of both sexes but not in blacks or Mexican Americans.

Triglycerides showed a slightly different pattern, rising between the late 1980s (118 mg/dL) and the early 2000s (123 mg/dL), but then falling again by 2010 (110 mg/dL).

All of these temporal trends persisted when the analysis was restricted to only the oldest adults, aged 50 and older.

During the study period, the number of adults taking lipid-lowering medications also rose, from 3.4% in 1988-1994 to 9.3% in 1999-2002 and to 15.5% in 2007-2010. However, these medications did not explain the entire improvement in lipid profiles, which also improved markedly in adults who weren’t taking them.

"The Healthy People 2010 guideline of an age-adjusted mean total cholesterol level of 200 mg/dL or less has been achieved in [all] adults, in men, in women, and in all race/ethnicity and sex subgroups. However, the age-adjusted mean LDL cholesterol level in adults of 116 mg/dL [remains] higher than the optimal range of below 100 mg/dL, [which is] associated with a lower risk of CHD [coronary heart disease]," Ms. Carroll and her colleagues said.

The researchers speculated that the favorable trends in lipid profiles might be attributable in part to a decrease in the consumption of trans-fatty acids and to other healthy lifestyle changes. The changes are unlikely to have resulted from increases in physical activity or decreases in the intake of saturated fat, as other studies have demonstrated that activity has not increased and saturated fat intake has not declined during the study period, they said.

This laboratory analysis of lipids was funded by the National Heart, Lung, and Blood Institute. NHANES is conducted by the National Center for Health Statistics and the Centers for Disease Control and Prevention. No conflicts of interest were reported.

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