Watching what you eat is important for heart health. But soon your cardiologist may be telling you to watch what you watch—at the movies—as well. Prior research has shown that stress can constrict the blood vessels, so doctors from the University of Maryland Medical Center wondered if watching movies that produced stress would have different effects from those that triggered good feelings.

What they wanted to know: Does watching movies that provoke specific emotions have any effect on the blood vessels?

What they did: The researchers showed 20 healthy volunteers short clips from two movies; the war drama Saving Private Ryan to elicit stress and the bowling comedy Kingpin to make them laugh. They separated each viewing by at least two days and had the volunteers fast and abstain from drinking alcohol the night before they came in for the study. The researchers measured each participant's blood pressure and blood vessel dilation before seeing the movie excerpts and throughout the 15-to-30-minute clips.

What they found: When watching Saving Private Ryan, the blood vessels of 14 of the participants (70 percent) constricted. During Kingpin, 19 of the participants' blood vessels (95 percent) expanded, increasing their overall blood flow. The researchers compared the constriction to the amount that has been found when people recall an angry moment and the expansion to what people experience after exercise.

What it means to you: Laughing at funny movies could help improve the dilation of blood vessels, leading to increased blood flow and better cardiovascular health. But, while this might support the adage that laughter is the best medicine, it certainly is not the only heart therapy. Keep your sense of humor—while shopping for heart-healthy diet.

Caveats: This study was done on a fairly small number of volunteers, and though the results are conclusive, the study would need to be done on more people to confirm how deeply laughter or stress from movies can affect the blood vessels. In addition, the results of this study were presented at a meeting of the American College of Cardiology, so the study hasn't yet been peer reviewed.

Find out more: The National Heart, Lung, and Blood Institute has information on how to prevent heart disease

For the latest news and tools to help you live a heart-healthy lifestyle, visit USNews.com's heart page.

Read the press release: www.umm.edu