Improved autonomic function may partly explain benefits of Mediterranean diet: Twin study

[Celebration]

http://www.theheart.org/article/1088041.do

A new study linking adherence to a Mediterranean-style diet and greater heart-rate variability in male twins may provide a new clue to understanding why a diet rich in vegetables, fruits, grains, and omega-3 fatty acids seems to reduce the risk of cardiovascular events, investigators say <1>.

The study, published online June 15, 2010 in Circulation: Cardiovascular Quality and Outcomes, showed that people with the highest scores—signifying that they ate a diet very similar to the classic Mediterranean diet—were significantly more likely than those with the lowest scores to have higher cardiac autonomic function, even after researchers controlled for genes and shared environment.

As Dr Jun Dai (Indiana University, Bloomington) and colleagues explain in their paper, lower heart-rate variability, defined by a range of time and frequency domains acquired by ambulatory, 24-hour ECG monitors, is an established measure of cardiac autonomic dysfunction—a risk factor for cardiac death. Previous studies have linked certain foods and nutrients to different levels of heart-rate variability, but the Mediterranean diet as a whole (combining a range of grains, vegetables, fruits, nuts, legumes, fish, and high olive-oil consumption) has not previously been examined in relation to heart-rate variability, they note.

Their study looked at food-questionnaire results from 276 middle-aged, mostly white, male twins participating in the Twins Heart Study and analyzed these alongside ECG recordings. They found that men with the highest Mediterranean diet scores (divided by quartiles) had significantly higher measures of heart-rate variability across all of the time and frequency measures taken. Adjusting for shared genes or environment, other nutritional factors, and overall energy intake had no effect on the overall results. For every one-unit higher score, Dai et al write, heart-rate variability parameters increased by roughly 4% to 13%.