Trans fat levels in the blood of white adults in the United States fell by 58 percent between 2000 and 2009, which should help lower the risk of cardiovascular disease in the nation, a U.S. Centers for Disease Control and Prevention study says.The findings suggest that public health initiatives to increase consumer awareness about the danger that trans fats pose to heart health and to help people reduce their consumption of trans fats have been effective, according to the researchers.