CHICAGO – Cholesterol levels among US adults improved between 1998 and 2010, according to a study published in the Oct. 17 issue of JAMA, a journal of the American Medical Association.

A study to examine trends in serum lipids in adults between 1988 and 2010, using three US cross-sectional National Health and Nutrition Examination Surveys, 1988-1994, which included a sample size of 16,573 adults, 1999-2002 (9,471 adults), and 2007-2010 (11,766 adults), was conducted by Margaret Carroll and colleagues of the Centers for Disease Control and Prevention, Hyattsville, Md. Included in the analysis were measurements of average levels of total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), non-high density lipoprotein cholesterol and geometric triglyceride. Researchers also examined the prevalence of lipid-lowering medication use.

Average TC declined from 206 mg/dL in 1988-1994 to 203 mg/dL in 1999-2002 and to 196 mg/dL in 2007-2010, the authors found. Similar trends over the 22-year period were observed in age-adjusted average TC levels for men and women.

There was a decreasing linear trend in age-adjusted average LDL-C levels for all adults, from 1988 to 2010, from 129 mg/dL in 1988-1994 to 123 mg/dL in 1999-2002 and to 116 mg/dL during 2007-2010.

“Although men had a higher age-adjusted mean LDL-C level than women during 1988-1994 and 1999-2002, during 2007-2010 there was no longer a sex difference,” the study relayed.

An increasing linear trend in age-adjusted average HDL-C levels was observed for all adults from 1988-1994 to 2007-2010. Between 1988 and 2010, a linear decline in age-adjusted, average, non-HDL-C level was observed for all adults. The age-adjusted geometric average triglyceride level for all adults increased from 118 mg/dL in 1988-1994 to 123 mg/dL in 1999-2002 and then declined in 2007-2010 to 110 mg/dL.

From 1988 to 2010, there was an increasing trend in the age-adjusted percentage of adults taking lipid-lowering medications, from 3.4 percent in 1988-1994 to 9.3 percent in 1999-2002 and to 15.5 percent in 2007-2010, the researchers also discovered. Among men and women age 50 years or older, increases in use of lipid-lowering medications of up to 35 percent were observed.

“Among adults not receiving lipid-lowering medications, trends in lipids were similar to those reported for adults overall,” the researchers said in the study. “Among obese adults, mean TC, non-HDL-C, LDL-C, and geometric mean triglycerides declined between 1988 and 2010.”

The researchers further hypothesized, “The favorable trends in TC, non-HDL-C, and LDL-C may be due in part to a decrease in consumption of trans-fatty acids or other healthy lifestyle changes, in addition to an increase in the percentage of adults taking lipid-lowering medications. They are unlikely to be the result of changes in physical activity, obesity, or intake of saturated fat.”

The study’s authors added the intake of saturated fat as a percentage of calories did not decrease between 1999 and 2008; little progress was made from 1998 to 2008 in increasing leisure-time physical activity levels of adults; and the prevalence of obesity among adults remains high, at more than one-third of the population.

They added “although the percentage of adults receiving lipid-lowering medications continued to increase between 1999-2002 and 2007-2010, declining trends in TC, non-HDL-C, and LDL-C also occurred for adults not taking lipid-lowering medications.”