A new report published by the Centers for Disease Control and Prevention says 66% of products containing trans fat have reduced their content of the heart-unhealthy fats since 2007. But most of those gains were made soon after research showed that the fats, found in partially hydrogenated vegetable oils and favored by the food industry for their stability and shelf life, raise bad LDL cholesterol levels while cutting good HDL cholesterol. Only 3.4% of the 270 products studied reduced trans fat content in 2010-2011. Categories showing the most improvement were doughnuts, crackers and pies, while rolls, margarines and microwave popcorns lagged; overall, microwave popcorn averaged highest in trans fat, with 4.5 grams per serving in 2007 and 3.8 grams still found in 2011. Noting that trans fat consumption is harmful even in low levels, researchers called for continued major efforts and commitment toward reformulating (or discontinuing) foods to eliminate trans fats.