Participants in a recently announced nationwide study wont get to eat chocolate candy in the name of science, but they will be testing the cocoa flavanols thought to give dark chocolate heart-healthy properties. The four-year study will give participants either a placebo or flavorless capsules containing doses of cocoa flavanols higher than could be easily obtained by eating chocolate. It will be by far the largest trial of the chocolate compounds, which previous findings have linked to improved blood pressure, cholesterol levels, artery health and other cardiovascular benefits. The National Heart, Lung and Blood Institute-sponsored study will recruit 18,000 men and women from other ongoing studies, including the Womens Health Initiative, to save time. A second arm of the study will also test whether multivitamins can reduce cancer risk in a broad population; recent research suggested such a benefit, but involved only male physicians.