Original: However, unlike in many other countries, trans fat levels of less than 0.5 grams per serving can be listed as 0 grams trans fat on the food label.
Simplified: For now, the US government's "Food and Drug Administration" has allowed makers of food products to label their products as having "0 grams of trans fat per serving" as long as the amount of trans fat in the food product falls below 0.5 grams per serving.