There is consistent evidence from observational studies of lower rates of cardiovascular disease (particularly cardiac and sudden death) in people with higher intakes, or higher blood levels, of fish oils (omega-3 fatty acids). Trials in people who have survived a heart attack have shown modest, but potentially worthwhile, reductions in coronary events. There have been, however, no large-scale trials of the use of fish oils for the prevention of vascular events in people without diagnosed arterial disease.