Study Finds Cholesterol Levels Improving Among U.S. Adults
According to a new analysis of national survey data published on Oct. 17 in the Journal of the American Medical Association, lipid levels among U.S. adults are moving in the right direction. From 1988 to 2010 there have been overall declines in total cholesterol (TC) and LDL cholesterol (LDL-C), and an increase in HDL cholesterol (HDL-C). While there has been an increase in the percentage of adults using cholesterol-lowering drugs over the same study period, the improved lipid profiles are seen in adults who do not use lipid-lowering drug therapy as well as in those who do.
The study used data from three National Health and Nutrition Examination Surveys (NHANES), including NHANES III (1998-1994), NHANES 1999-2002 and NHANES 2007-2010, and found that mean TC levels declined from 206 in 1988-1994 to 196 in 2007-2010 (p<0.001) and mean LDL-C declined from 129 mg/dL to 116 mg/dL (p<0.001) over the same period. Mean non-HDL-C declined from 155 mg/dL to 144 mg/dL (p<0.001) while mean HDL-C increased from 50.7 mg/dL to 52.5 mg/dL (p=0.001).
Further, the geometric mean triglyceride level increased from 118 mg/dL in 1988-1994 to 123 mg/dL in 1999-2002, then decreased to 110 mg/dL in 2007-2010 (p<0.001).
The use of lipid-lowering medications increased from 3.4 percent of adults to 15.5 percent (p<0.001) over the survey period. At the same time, among adults who were not taking lipid-lowering medications, trends for TC, HDL-C, LDL-C, and triglycerides were similar to the trends seen for the adult population overall.
The authors suggest that the favorable trends may be due in part to a general decrease in the consumption of trans-fatty acids, positive lifestyle changes and increases in the percentage of adults taking lipid-lowering medications. The general intake of saturated fat has not changed significantly between 1999 and 2008, nor has the general level of physical activity changed significantly. A general decrease in the prevalence of cigarette smoking and carbohydrate intake may have contributed to the increase in HDL-C and the decrease in triglycerides.
"The Healthy People 2010 guideline of an age-adjusted mean TC level of 200 mg/dL or less has been achieved in adults, in men, in women and in all race/ethnicity subgroups," said lead author Margaret Carroll, MSPH, National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Md. "However, the age-adjusted mean LDL-C level in adults of 116 mg/dL is higher than the optimal range of below 100 mg/dL associated with a lower risk of coronary heart disease."
Carroll notes that further work is needed to assess simultaneously the effects of trans-fatty acids, lipid-lowering medications and healthy lifestyle factors on TC, HDL-C, LDL-C and triglycerides.
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