Despite Americans’ growing girth and an increase in obesity-related diseases, cholesterol levels among adults in the United States have taken a turn downward, even in those who aren’t taking cholesterol-lowering medications such as statins, according to an analysis of national health surveys released Tuesday.

That review, conducted by the National Center for Health Statistics and the federal Centers for Disease Control and Prevention and involving more than 10,000 Americans, found a 5 percent drop in total cholesterol levels from 1988 to 2010, when the latest survey was conducted. The surveys involved in-person interviews, physical exams, and screening blood tests.