It's no joke – regular laughter may be good for your heart.

American researchers reported Monday that daily laughter may prevent heart disease because it makes blood vessels work more efficiently.

The study, which was presented at a meeting of the American College of Cardiology in Orlando, Florida, found that while laughter is not a substitute for exercise, it has much the same effect.

Researchers from the University of Maryland School of Medicine in Baltimore showed two different movies to 20 healthy volunteers. One movie was stressful, the other humourous.

Better blood flow

The researchers then measured blood flow, looking in particular at the blood vessel lining called the endothelium.

They found that blood flow was reduced in 14 out of 20 volunteers who watched the stressful film, but it flowed significantly more freely in 19 out of 20 subjects when they laughed at the funny movie.

The scientists say laughter has many of the same benefits as aerobic exercise, but without the aches and pains.

They recommend 30 minutes of exercise three times a week and 15 minutes of laughter every day to maintain a good vascular system.