A new study shows that the rate of coronary artery disease among U.S. service members has declined sharply in the past half century, falling to roughly 1 in 10 military personnel today from about 8 in 10 during the Korean War.

The findings came as a surprise to some researchers, who expected that the nationwide rise in obesity and Type 2 diabetes, including among young people, might have led to a similar trend in heart disease in the military. But instead it appears that national reductions in other risk factors for heart disease, like hypertension, smoking and high cholesterol, have had a greater effect on cardiovascular health.

Some experts had debated whether the steep decline was real, given that those in today's all-volunteer military are fitter than the general population and, presumably, those who served during the draft era of the Korean War. But most said the trend was hard to dispute.

"The changes in prevalence of coronary disease are so great that I can only conclude that most of the differences are likely real," said Dr. Daniel Levy, a cardiologist and director of the National Heart, Lung and Blood Institute's Framingham Heart Study, who was not directly involved in the study. "This isn't a subtle difference; it's a vast difference."

The authors of the new study, which was published in the Journal of the American Medical Association on Tuesday, drew their findings from autopsies and medical records of nearly 4,000 service members killed in Iraq and Afghanistan from 2001 to 2011. Most of them were men, with an average age of 26. Overall, 8.5 percent had some degree of hardening and narrowing of the coronary arteries, known as coronary atherosclerosis.