The research was conducted with twins to try to eliminate the possible effect of genetics as much as possible.
Using data from the Emory Twins Heart Study, the researchers found that men eating a Mediterranean-style diet had greater heart rate variability (HRV) than those eating a Western-type diet.
Heart rate variability refers to variation in the time interval between heart beats during everyday life - reduced HRV is a risk factor for coronary artery disease and sudden death.
"This means that the autonomic system controlling someone's heart rate works better in people who eat a diet similar to a Mediterranean diet," said Jun Dai, study author and assistant professor of nutrition and epidemiology at Indiana University in Bloomington.
Eating a Mediterranean-style diet - one characterized by low saturated fats and high in fish, fruits, vegetables, legumes, nuts, olive oil, cereals and moderate alcohol consumption - reduces a person's heart disease risk. But until now, the way the diet helps reduce the risk of coronary disease remains unknown.
Dai and her colleagues analyzed dietary data obtained from a food frequency questionnaire and cardiac data results from 276 identical and fraternal male twins.
They scored each participant on how closely his food intake correlated with the Mediterranean diet; the higher the score, the greater the similarity to a Mediterranean-style diet.
To measure HRV, participants had their heart's electrical activity continuously measured and recorded with a Holter Monitor, a portable, battery operated electrocardiogram device.
The research has been reported in Circulation: Cardiovascular Quality and Outcomes, an American Heart Association journal. (ANI)