Do you have less artery-clogging trans fat in your bloodstream than you did twelve years ago? According to a new study, you probably do:

The amount of trans fat in the American bloodstream fell by more than half after the Food and Drug Administration required food manufacturers to label how much of the unhealthful ingredient is in their products, according to a new study.

Blood levels of trans fat declined 58 percent from 2000 to 2008. FDA began requiring trans-fat labeling in 2003. During the same period several parts of the country — New York most famously — passed laws limiting trans fats in restaurant food and cooking. The makers of processed food also voluntarily replaced trans fats with less harmful oils.

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.

Opponents of New York City's synthetic trans fat ban claimed that the measure be unenforceable. When the ban took effect 50% of restaurants were using synthetic trans-fats, two years later only 2% were.