The decline, unusually big and abrupt, strongly suggests government regulation was effective in altering a risk factor for heart disease for a broad swath of the population.
Researchers at the Centers for Disease Control and Prevention discovered the decline by analyzing blood drawn as part of the National Health and Nutrition Examination Survey, which interviews and examines a sample of Americans at least once a decade.
The trend was seen in white adults; researchers are looking to see if it occurred in other ethnic and racial groups, too.
Trans fats, which are used for deep-frying and as an ingredient in baked goods and spreads, increase the risk of heart disease. One study found that if a person increases total calorie intake 2 percent all in the form of trans fat, risk of a heart attack rises by about 20 percent.
“Our findings provide information about the effectiveness of these interventions,” said Hubert W. Vesper, a CDC chemist who headed the analysis. “This reduction is substantial progress that should lower the risk of cardiovascular disease in people.”
The study, in the Journal of the American Medical Association, also found a decrease in LDL (the “bad cholesterol”) and an increase in HDL (“good cholesterol”) between 2000 and 2009. That healthful trend could be a result of the trans-fats decline, other dietary changes, increase in exercise, or use of cholesterol-lowering statin drugs.
New York City’s trans-fat ban took effect in December 2006. It covered only “artificial” trans fats created in the manufacturing of cooking oil and other products. It didn’t restrict trans fat that naturally occurs in some foods.
By November 2008, 98 percent of restaurants were not using trans fats in oils, shortenings and spreads, compared with 50 percent in the year before the ban.
California banned trans fat in restaurant food by 2010 and in retail baked goods by 2011. Other localities, including Montgomery County, also have enacted bans.